Biological Sciences Task Cells Biology Essay

Biological Sciences Task Cells Biology Essay Cells are grouped to form tissues, and each of them has specialised role. Our body develops from a cell known as the zygote that is the consequences of the fusion of the female ovum (egg cell) and the spermatozoon of the male (germ cell). Single cells are very tiny and cannot be seen with the naked eye. Cell types are distinguished by their dye (colouring) and by their shape and size. Cells consist of plasma membrane within which is number of organelles. Nucleus: it is a small electron particles composed of ribosomal RNA. The nucleus contains our bodys genetic substance that is in the form of large molecules of deoxyribonucleic acid (DNA). There are dozens of DNA molecules called chromosomes. The molecule of DNA is a series of nucleotide molecules known as proteins, and are connected by phosphate-sugar molecules. The nucleotide molecules contain one of the following materials known as bases: adenine (A), thiamine (T), guanine (G), cytosine (C). The bases are in set pattern; an in one chain is matching with T in the other and G with C. In this order of arrangement, each chain is complementary to the other. Every cell has the total match of genes needed to synthesise all the proteins, but majority of cells merely synthesise proteins that are suitable for their functions. It means enzymes can only be produced if the controlling gene is present, and when gene is missing, the linked enzyme is missing and there will be no chemical change. The RNA is responsible for the transfer of information from DNA to the cytoplasm where proteins are synthesised. Genetic information passes from DNA to RNA encouraging protein synthesis. (Anatomy and Physiology, 7th ed, 1990). Cell membrane: it is the most important organelle; it holds and keeps the cell intact. Cell membrane is moveable, and it moves along narrow passage. It is made up of phospholipids bilayers (two molecule layers), and has hydrophilic heads which are soluble in water and hydrophobic tails which are not soluble in water. The head has lipid molecules and a phosphate group (PO4) at the end. The apex and underneath layers of the membrane have stems that are facing each other. It also has proteins of which some are with carbohydrate. The cell membrane has 4 major functions, which are to maintain homeostasis, control the materials that can go in and out of the cell, and hold the cell together. (Cdli.ca, 2010) Cytoplasm: it is the basic substance that fills the cell, a fluid jelly-like substance that is eight percent (8%) water and typically plain in colour. Cytoplasm is also called cytosol (cell substance). It is found within the cell membrane and surrounds the nuclear cover and the cytoplasmic organelles. It is a substance that is made up of molecules and in which all the cells organelles are suspended and held as one by a fatty membrane. Cytoplasm can only be seen through an electron microscope, and it comes into view as a three dimensional lattice protein rich strands called microtrabecular lattice (MTL). It interconnects and holds other hard (solid) structure in the cytoplasm. The cytoplasm helps to move substances and it changes shape as it moves. (sln.fi.edu, 2010). Task 1.2 Explain the structure and function of the main cellular organelles. Nucleus: they are small electron particles that have ribosomal RNA. The RNA is responsible for the transfer of information from DNA to the cytoplasm where proteins are synthesised. Genetic information passes from DNA to RNA encouraging protein synthesis. (Anatomy and Physiology, 7th ed, 1990). Cell membrane: it is a sphere-shaped structure, and it is rich in ribosomal RNA and protein. It surrounds the contents of the cell and controls the flow of materials into and out of the cell. (HUMAN BODY, 2001). Mitochondria: it contains varieties of organelles, e.g, mitochondria and lysosomes. They are found in the cytoplasm and sometimes referred to as the power house of the cell. It produces a material known as adenosine triphosphate (ATP) which carries energy in all cells. (Anatomy and Physiology, 7th ed, 1990), (HUMAN BODY, 2001) Endoplasmic reticulum: it contains DNA and synthesises specialised proteins, e.g., muscle protein and steroid hormones, and it is linked with detoxification (process of removing a toxic substance) of some drugs. Endoplasmic reticulum is dotted with ribosomes, which consist of RNA. It helps to transport substances through the cell. (Anatomy and Physiology, 7th ed, 1990), (HUMAN BODY, 2001) Nucleolus: a tiny structure that is inside the nucleus. It permits the transportation of water-soluble molecules across the nucleus. Golgi complex: a heap of compressed sacs. It receive and process protein, the proteins are made to order and then released at the cell membrane. (HUMAN BODY, 2001) Lysosomes: potent enzymes; they mortify dangerous substances that is in the cell, and also dispose of other unwanted materials and weary organelles. (HUMAN BODY, 2001) Ribosome: they are tiny granular structure, and they play major role in the gathering of proteins. (HUMAN BODY, 2001) Nuclear pores: a membrane bound vesicle; plays a part in cellular digestive system. Task 1.3 Describe the role of nucleic acids in protein synthesis. DNA (deoxyribonucleic acid) is the genetic substance from which chromosomes in cells nucleus are formed, and it controls protein synthesis and inheritance (transmission of genetically controlled characteristics). Protein synthesis begins when the DNA coils provisionally relax at exact points. In the nucleus a doubled strand of DNA temporarily partly untwists. Transcription, which is the copying of the nucleus bases on one strand of DNA, begins to happen. Free bases match with those on DNA; adenine joins with thymine, guanine with cytosine, uracil substitutes thymine and joins with adenine. Forming a strand of messenger RNA. A completed strand of messenger RNA separates from the DNA, which twists back into place. The messenger RNA leaves the nucleus carrying the code for a protein into the cytoplasm. The messenger RNA with its series of codons (units of three nucleotides) for amino acids, attaches to a ribosome and translation starts. Translation, the sequencing of amino acids happens when free tRNA with its anticodon (units of three nucleotides) from the cytoplasm matches up and links to mRNA. When second tRNA joins, a peptide bond links the two amino acids at the ends of tRNA together, starting a peptide chain. The first tRNA separates leaving its amino acid behind. The ribosome moves along the mRNA reading the code. A third tRNA joins and the next amino acid is connected by another peptide bond. The synthesis continues until a stop or termination codon completes the process and the assembled polypeptide or protein is released. (HUMAN BODY, 2001). Task 2.1 Describe the structure and function of the cell membrane. Image of Cell membrane (lamp.tu, 2010). Cell membrane consists of a bilayer (two layers of molecules) of phospholipid (head and two tails) that is surrounded with mobile proteins. The phosphate head of phospholipid is hydrophilic, and the fatty acid tails are hydrophobic. The membrane structure depends on fatty acids molecules (lipids) in other to spread on the water surface. It is only one end of the lipid molecule that is attracted by water and the whole hydrocarbon tail is hydrophobic. The molecules form a monomolecular film on the water surface and scatter as very small droplets (drop of liquid). Fatty acids are able to support a double lipid bilayer when it is paired. Fatty acids in membranes are paired as phospholipids and glycolipids, joining saturated and unsaturated chains. Phospholipids are plentiful in membranes and glycerol, and are usually at the main structure. The fatty acid membrane is the storage place of the cell, it protects its content from dispersing casually, and it also permits control of the internal environment. Two lipid layers adhere to one another, in a double membrane, while it exposes water-soluble heads. Lipid molecules are free to glide in their layer. Common polar groups are ethanolamine, serine and choline. Sphingolipids are phospholipids with serine, their saturated hydrocarbon tails are usually longer and straighter than other membrane lipids, and it allows them cluster into rafts, which floats inside the membrane. Glycolipids are restricted to the external layer of the cell membrane. They are constructed like phospholipids, but the serine substitutes glycerol. Polar sugar chains might extend outside from the glycolipid molecules. Cholesterol straightens membranes by reducing fluidity of lipid. Rafts in particular, are rich in cholesterol. Tiny molecules that are soluble in oils, easily pass through the lipid bilayer, and they are O2 (oxygen) and CO2 (carbon dioxide). The lipid bilayers present a solid barrier to ions and other small molecules. The larger molecules do not have any chance of passing through lipid bilayers. The larger molecules are H+ (hydrogen), Na+ (sodium), K+ (potassium), Mg+ (magnesium), Ca+ (calcium), Cl+ (chlorine) and H2O (water). Membrane proteins has major role in determining what goes in and out of the cell. They detect and bind specified molecules, and then move them through the membrane barrier. About a half of the membrane has protein chains, the amount might be less in nerve cells because the membranes are rich in complex fatty acids. About a third of the cells genetic substance (DNA) codes for membrane proteins show their importance to the cell. Proteins are strings of amino acids, known as polypeptides. They fold into molecular sculptures (three dimensions), which they need in other to perform task that depend on their exact shapes and properties. Some proteins are at one side of the membrane while others go all the way through. Transmembrane protein channels transport specific molecules across the membrane. Majority of transmembrane protein have helical sections with other portions that are exposed on whichever side of the membrane. Helical section might come together to form tunnels. The helices cre ate a wave of contraction that moves ions from one side of the membrane to the other. Tiny ions, like potassium, calcium and sodium vigorously conduct across membranes by ATP-powered pumps. Some protein tunnels depend on gate to control the passive (inactive) flow of water and other polar molecules through the membrane bilayer. Protein chains might cross as beta sheet basket- like channels and allow larger molecules to pass. Protein chains might fasten in an electricity static state inside on leaflet, of the membrane, leaving the active domains to protrude (stick out) from the membrane. Long sugar chains (oligossacharides) attach to the external surface of the membrane proteins and glycolipids to form the glycocalyx. The glycocalyx declare the cells identity to the exterior. Membrane can overwhelm substances from the exterior. Endocytosis (membrane navigation) encloses large objects and drag them into the cell. Other viruses use their own membrane which can combine with the cell mem brane. (John Kyrk, 2010). Task 2.2 Explain the differences between osmosis, diffusion, active transport and bulk transport. Cells move water molecules, food particles, and other substances through the membranes. Things like water pass through easily, and others have to be moved through the channels. Solute; is a substance that dissolve in solvent to formulate solution, and solvent is a substance in which solute is dissolve to make a solution. Example is saltwater, in which salt is the solute, and water is the solvent. Diffusion is the mixing of two substances by random motion of molecules. Molecules move from an area of high concentration, to an area of low concentration. When the molecules spread out equally, diffusion stops, because there is no longer a concentration of gradient (steepness). Concentration gradient, is the difference between the concentration of molecule in one area and the concentration of molecule in an adjacent (beside) area. The system has reached its equilibrium, when the concentration of solute is the same throughout a system. Osmosis is the diffusion of water across a semipermeable (allows some types of things pass through) membrane. Water moves across membrane from a region of high concentration of water, to an area of low concentration of water. Facilitated diffusion is a movement of particles and diffusion across the cell membranes with the help of proteins in the membranes. Particles move down the concentration gradient going from high concentration to low concentration. Facilitated diffusion increases the rate of particles that cross the cell membrane. (biologymad.com, 2010) The process of diffusion, osmosis, and facilitated diffusion, does not need any energy to be used by the cell. The three processes are known as passive transport. The processes by which the cell uses energy to move particles across the membrane, is known as active transport. The cell movement of things from low concentration, to high concentration, is known as active transport, because it needs energy to do so. The cell uses active transport to keep the right balance of sodium and potassium ions in and out of the cell. This balance is vital for muscle contraction, nutrient absorption, and nerve pulse transmission. Bulk transport is for the movement large particles in and out of the cell. During bulk transport, large particles move across cell membrane packed in membrane-bound sacs. Bulk transport is of two types; exocytosis and endocytosis. Exocytosis is to move from inside the cell, to outside the cell. Wastes and cell products are packaged by the Golgi body in sacs known as Golgi vesicles. The vesicles combine with the cell membrane and materials are secreted outside the cell. Endocytosis are materials brought into the cell. Part of the cell membrane surrounds a particle that is outside the cell. The cell pinches a part of its outer membrane to form a new vesicle. When the vesicle is within the cell, it can combine with other organelles or release its contents into cytoplasm. There are two types of endocytosis; the pinocytosis and the phagocytosis. Pinocytosis is when a cell membrane surrounds a droplet of fluid and bring into the cell. Phagocytosis is when a cell engulfs (overwhelm) a solid substance and bring into the cell. Phagocytosis engulfs (surrounds and swallow) and destroys bacteria and other invaders of the body. Hypertonic solution; the concentration of solutes is higher than the concentration of solutes inside the cell, example is potatoes in salt water, water left the cells (diffuses out) and the potatoes became flexible. Hypotonic solution; solutes concentration is lower than the concentration of solutes inside the cell. Water diffuses into the cell, an example, is potatoes in distilled water, the water came into the cells, making the cell to swell and the potatoes becomes rigid Isotonic solution; the concentration of solutes equals the concentration of solutes within the cell. (biologymad.com, 2010) Task 2.3 Give examples of materials exchanged by different methods with a justification in each case. Diffusion: is a very slow process, materials exchanged, are gases oxygen and carbon dioxide. The lungs have high concentration of oxygen (O2) in the air sacs (alveoli), and a low concentration of oxygen in the blood of pulmonary capillaries. Carbon dioxide (CO2) has a low concentration in the alveoli, and a high concentration in the blood of the pulmonary capillaries. Oxygen diffuses from the air to the blood, and carbon dioxide diffuses from the blood to the air. (maexamhelp, 2010). Osmosis: it is where the cells lining the small intestine, absorb water. The exchanged material is salt. Cells take in salts and become more salty, and then water follows the salts into the cell. This process also takes place in kidneys because of its large demand of water. (maexamhelp, 2010) Active transport: nerves and muscle cells have sodium pump. Sodium ions (Na+) continually diffuse into the cell area of smaller concentration. Incoming sodium ions (Na+) are returned outside by the sodium pump. The nerve and muscle cells continually produce ATP to keep their sodium pump working. Another example is the assimilation of glucose and amino acids by the cells. The cells assimilate nutrients from digested food by the use of ATP. (maexamhelp, 2010). Filtration: blood pressure is formed by the pumping of the heart. Blood pressure force plasma and dissolve materials through the capillary membranes into the surrounding tissue spaces. This facilitates the creation of more tissue fluid and is also how cells get glucose, amino acids, and other nutrients. (Maexamhelp, 2010). Phagocytosis and Pinocytosis: cells that are stationary (immobile) receive small molecules that are attached to their membranes. The cells of the kidney tubules reabsorb small proteins by pinocytosis. (maexamhelp, 2010). Task 3.1 Explain the difference between mitosis and meiosis and explain when each occurs. Mitosis and Meiosis are both cells that have tricky division processes. Duplication of DNA occurs in both of them. The difference between mitosis and meiosis is well understood only if we know what the two cell division processes are, and they are as follows: Mitosis is a cell division process that involves eukaryotic cell dividing the chromosomes in two identical set of two daughter nuclei inside its cell nucleus. This is followed by cytokinesis that equally divides the nuclei, cytoplasm, organelles and cell membrane, into two daughter cells. Both mitosis and cytokinesis come together and form the mitotic (M) stage of the cell cycle. This series of events are divided into different stages known as prophase, prometaphase, metaphase, anaphase and telophase. Mitosis happens in different ways and in different species (types). Animals, for example, go through an open mitosis process which involves the breaking down of the nuclear envelope before the chromosomes separate, and the fungi and yeast go through a close mitosis process in which the chromosomes divide inside an intact cell (undamaged cell) nucleus. (buzzle.com, 2010) Meiosis is a reduction division process that halves the number of chromosomes per cell. The DNA in the original cell is duplicated during S-phase of the cell cycle, before it starts. Meiosis separates the identical chromosomes into four haploid (a single set of unpaired chromosomes) gametes. If gametes are produced, the cells will fuse (combine) during fertilisation to produce a new diploid cell (two matched chromosomes sets). Meiosis go through fertilisation in plants. The different stages of meiosis are meiosis l, prophase l, metaphase l, anaphase l, telophase l and ll. Meiosis is needed for sexual reproduction, it occurs in all eukaryotes that reproduce sexually. It does not occur in archaea because they reproduce asexually (no fusion of male and female sex cells gametes). (buzzle.com, 2010) The differences between mitosis and meiosis are as follows: No. Mitosis Meiosis 1 Takes place inside somatic cells. Takes place inside gamete cells. 2 A single division of the mother cell results in two daughter cells. Two divisions of the mother cell results in four meiotic haploid gametes. 3 A mitotic mother cell can either be haploid or diploid. A meiotic mother cell always diploid. 4 The number of chromosomes per nucleus remains the same after division. The meiotic products contain haploid (n) number of chromosomes in contrast to the (2n) number of chromosomes in mother cell. 5 It is preceded by a S-phase in which the amount of DNA is duplicated. In meiosis, only meiosis is preceded by an S-phase. 6 In mitosis, there is no pairing of homologous (similar) chromosomes. During prophase l, complete pairing of all homologous chromosomes take place. 7 There is no exchange of DNA between chromosomes. There is at least one DNA exchange per homologous pair of chromosomes. 8 The centromeres (region joining two parts of chromosome) split during anaphase. The centromeres do separate during anaphase ll, but not during anaphase l. 9 The genotype type of the daughter cells is identical to that of the mother cells. Meiotic products differ in their genotype from the mother cell. 10 After mitosis, each daughter cell has exactly the same DNA strands. After meiosis, each daughter cell has only half of DNA strands. (buzzle.com, 2010) Task 4.1 Explain the need for cellular specialisation in multi-cellular organism. Each human cell has different shape and size that depend on their specialised function. Speed of cells division varies; it is very fast mostly in epithelial cells, and continually replaces itself. However, it is slow or non-existent in a structural complex cell. Specialised cells are: Epithelial cells: they are from the skin, and cover most organ and line hollow cavities. Photoreceptor cell: is a type of light-sensitive cell that is found in the retina of the eye. They are activated by bright light and are responsible for colour perception (interpreting information from senses). (Integrated body, 2010) Red blood cell: a bag of oxygen-carrying haemoglobin molecules. Its biconcave shape allow for maximum oxygen absorption. (Integrated body, 2010) Adipose (fat) cell: its main cells, adipocytes, are bulky (large) and are jam-packed with droplets of lipids (fats), which store energy in case the diet cannot meet requirements. (Integrated body, 2010) Smooth muscle cell: this large, elongated (extended), spindle-shaped cells of smooth muscle are called muscle fibres. Its shape allow for contraction by means of sliding strands of protein within. (Integrated body, 2010) Nerve cell: every cell consist of configuration of short extensions known as dendrites, which is to receive nerve signals, and also has a long wire called axon, which is to send signals to other cells. (Integrated body, 2010) Sperm (egg) cell: every sperm has a head that transport the paternal (fatherly) set of genetic substances. It has a whip-like tail that propels it towards the egg. (Integrated body, 2010) Ovum (egg) cell: they are giant cells and contain the maternal (motherly) complement of genetic material, and energy resources for the first cell divisions that shape early embryo. (Integrated body, 2010) Task 4.2 Describe major tissue types and their functions. Tissues are groups of similar cells that carry out a common function. There are four groups of tissues in our body. They are epithelial, connective, muscle and nerve. Major tissue types and functions, are as follows: (Integrated body, 20100 Areola: a loose connective tissue, half-solid, allows food to pass through, inside has two other connective tissue types. They are yellow elastic and white fibrous with fibrocytes and mast cells that manufacture histamine a protective inflammation and heparin an anti-coagulant. They are mostly found in the body, connecting and supporting other tissues, such as between muscles and supporting blood vessels and nerves. They function as connection and support to other tissues. Adipose: these are fat cells that have fat globules. They are located between muscle fibres, under skin, around kidneys and at back of eyes. Their function is to protect, insulate and act as food reserve. Lymphoid: half (semi) solid tissue, some white fibres, lots of cells, of which majority are lymphocytes and reticular cells. They are found in lymph nodes, thymus gland, spleen, tonsils, appendix, walls, of large intestine and glands of small intestine. They function to form lymphatic system cells and blood cells. Lymphocytes and reticular cells function to control disease. Yellow elastic: this is elastic fibres, and very few cells. They are located in the lung tissue, bronchi and trachea, arteries, stomach, bladder and other stretchy or recoiling organs. They function as tissue enabling great expansion and recoil (shrink back). White fibrous: it is a strongly connective tissue, but not elastic. They are mostly closely packed bundles of collagen fibres. The fibres run in same direction. They form ligaments and periosteum (material making up bones) of bone. They form outer protection of organs, for example, protection of kidneys, brain and muscle fascia. Their function is connection and protection. Bone: it is the hardest structure of the body. It is compact outside and cancellous (not solid) inside. It has 25% water, 30% organic substance, and 45% inorganic salts. It is found in the skeleton. As compact, it functions as dense for strength, support and protection. And as cancellous, it functions as structure bearing and cellular development. Blood: is a fluid connective tissue, it has forty five percent cells, and fifty five percent plasma. It circulates inside cardio vascular system, and cells in cell production location. Its function is to transport food and oxygen to all cells and removal of waste from them. It also fights infection and clot blood. Cartilage: it is firm, tough, solid tissue. It has cells known as chondrocytes, and is of three types. Hyaline; is a blue and white smooth chondrocyte cells grouped together in a solid matrix (medium) and mainly resilient (hard-wearing). It covers parts of bone that form joints. The costal cartilages, parts of larynx, trachea and bronchi. Its role is connection and protection. Yellow elastic cartilage; these are fibres running (flowing) through a solid matrix. It contains fibrocytes and chondrocytes between multi-directional fibres. They are found in the pinna, the external cartilage of the ear, epiglottis, flap which prevents food and liquid entering trachea. It is flexible function. White fibrocartilage; white fibres packed with dense masses (lump). They are tough, a bit flexible, and contain chondrocytes. It is located in intervertebral discs, semi-lunar cartilages, and hip and shoulder sockets. Its function is to absorb shock. Task 4.3 Analyse body systems and assess the interdependence of their functions. The body systems are group of parts that are connected. They include organs and tissues that work together to perform particular functions. The system has separate processes inside the body, and each is dependent on the others. They work together as efficient functioning supportive system. Skeletal system: this is the skeleton, it a solid framework that is moveable and supportive of the body. It is where the rest of the body is built. The bone has a role in the other body systems. It is where white and red blood cells grow to build up a fatty tissue called red marrow. Its essential minerals, such as calcium, are stored in the bone, and to be released when there is shortage. Muscular system: it consist about half of the bodys bulkiness. It works with the skeleton, and its voluntary muscles allow the body to be exact in movements. The involuntary muscles, that comprise the heart muscle and the smooth muscle, are meant to provide the essential power (force) for the working (functioning) of the respiratory, cardiovascular, and the digestive systems. Nervous system: this is the brain, and it is the site of both consciousness and creativity. The brain, through the nerves of the spinal cord and the system of nerves that branch to all other parts of the body, controls all body movement. It also communicates with the endocrine glands and influences the functions of the other body system. Endocrine system: this is the hormones and chemicals that act (take action) on specified tissues, and then affect the bodys interior balance. It is secreted by endocrine glands and other organs. It flows in the blood and other body fluids, and also starts the changes that take place during puberty. Cardiovascular system: its most basic function is pumping blood around the body. It supplies all organs and tissues with oxygenated nutrient blood. It can get use to changes in demand quickly. Waste products are removed during blood circulation. Lymphatic system: it provides very important protection from infectious disease and also prevents malfunctioning of the internal tissues. (JK, 2010) Respiratory system: it is made up of the nose (nasal cavities), which filter inward bound air. Also consists of the pharynx, the larynx, the trachea, the lungs and the air sacs. It is the site of oxygen and carbon dioxide exchange. Digestive system: the work of the digestive system is to reduce large and complex substances to water soluble so that the cell can use them. The process is both physical and chemical. The digestive system is of two parts; the alimentary canal (mouth, anus, throat, oesophagus, stomach), and the small and large intestines. Urinary system: its excretory organs get rid of liquid wastes. The nephrons filter the blood and remove unwanted substances as wastes, and return necessary substances and fluids to the blood. The expelling of urine waste is started by the voluntary relaxing of the sphincter. In the female, the urethra empties in the area between the clitoris and the vagina opening. And in the male, urethra, which is about twenty centimetres long, runs through the penis. Male reproductive system: it is where sperm are produced and contained in the scrotum. The sperm and its fluid are known as semen. The semen is ejaculated into the urethra and penis, and from there, into the females vagina. Female reproductive system: it is about seven to ten centimetres long, receives the sperm from the male. The sperm must reach the uterus. The cilia assist the sperm as they swim up towards the egg. A fertilised egg is formed if a sperm enters the egg, and it is called zygote. The zygote passes through the uterus and becomes attached to its lining. The cells increases and develop into fetus (unborn offspring). (Human Anatomy, 1982). Homeostasis: all of the human bodys systems work together to maintain equilibrium, two of the body systems are very important for the maintenance of homeostasis. They are the nervous and endocrine systems.

The Evolution and Mechanism of Immunological Memory and Its Impact on Immunology Research.

The Evolution and Mechanism of Immunological Memory and its Impact on Immunology Research. Recently, the Center for Disease and Control reported that it has discovered a super bug, a bacteria, that has the capability of resisting almost any antibiotic known to human. In addition to resisting antibiotics, these superbugs are deadly. Not only do the bugs cause death to half of the patients with serious infectious diseases, but they also spread their genes that make the bugs resistant to other bacteria cells (USA TODAY, 2013). This class of superbugs is known as carbapenem-resistant enterobacteriaceae (CRE).Currently, CRE are found mainly in hospitals and nursing homes. However, if these bacteria escape into the environment, the results can be devastating. For instance, the bacteria may cause small diseases, such as the common cold, to become untreatable because the CRE alters the small disease genetics in a way where it is resistant to vaccination and other medicines (USA TODAY, 2013). Although this type of bacteria is new and deadly, it is not the first time that the world has encountered something similar to CRE. For instance, Staphylococcus aureus is one of the well-known examples of bacteria that are resistant to antibiotics.One reason doctors use antibiotics is because bacteria are often resistant to the immune system of a body. The resistance of bacteria to the immune system is due to natural selection and genetic mutation. Because bacteria reproduce at a rapid rate, some bacteria that contain the adaptive, resistant traits survive and reproduce offspring that contains the resistant genes. They produce immune-resistant genes through genetic mutation. The alteration made by the genetic mutation can create a trait that is resistant to the immune system.As a result, the genetically mutated bacteria will be able to reproduce without interference from the host’s defense system. As a powerful tool that the body uses to protect itself from pathogens and bac teria, the immune system consist of several parts, and the immunological memory is one of the most important. Understanding the evolution and the mechanism of both the immune system and immunological memory, new research areas can be developed and new vaccines can be created that target the immune systems of pathogens or that alter the immune system to make it more efficient in combating pathogens.Evolution of the innate immune system and the innate memory Organisms of the same species’ innate memory are almost the same. This memory comes from millions of years of evolution (Sompayrac, 2008). The immunological innate memory is based on pattern recognition receptors. Pattern recognition receptors are the main components that allow the innate immune system to recognize the pathogens and activate antigens (Kurtz, 2004). These receptors have gone through millions of years of evolution. One of the main receptors is the Toll-like receptors (TLRs) (Sompayrac, 2008).Instead of studyi ng the body’s defense to pathogens, current research investigate the evolution of the innate immune system through observing the examples of specific receptors in simple organisms. Wu and Huan (2011) are studying the Toll/interleukin-1 receptor (TIR) and the leucine-rich repeat (LRR), which are the two domains that make up the TLR. TIR and LRR are connected by a transmembrane helical starch that is 20 amino acids long. TIR plays an important role in activating the innate immune system by detecting lipopolysaccharide from gram-negative bacteria.The interaction between the receptors of both the innate immune system and bacteria is handled by LRR. Figure 1: Illustration of evolutionary tree of invertebrates. Amphimedon came before Cnidarians. (Wu and Huan 2011) To understand the evolution of TLR, scientists have to discover when the TIR and LRP first appeared. One research conducted by Dr. Wu and coworkers (2011) attempted to create a phylogenetic tree of the TLR. After comparin g the protein of different organisms, they discovered that sponges, such as Amphimedon queenslandica, contained a single TIR domain that was distinctly related to the TLR of vertebrates (Wu and Huan, 2011).The finding prompted them to conduct further analyses of TIR proteins in organisms that appeared later than Amphimedon queenslandica. As shown in Figure 1, cnidarians appeared after Amphimedon queenslandic. Cnidarians had TIR proteins that were similar to that of vertebrates. Cnidarians are one of the simplest organisms, and their TIR proteins allow them to have the characteristics of allorecongnition, the ability to distinguish its own tissue from another (Wu and Huan, 2011). LRR was not found in cnidarians.The finding of TIRs that were similar to vertebrates in cnidarians only answered part of the question. Wu and Huan were not able to find the first appearance of LRR. They found the combination of LRR and TIR to make TLR after analyzing the TLR proteins of three basal deuterost ome invertebrates and five protostome mammals. The conclusion is that the combination of TIR and LRR occurred after the divergence of bilateria and nonbilateria. After the separation, the receptors became more complex because they started to have the capability of allorecongnition and a killing mechanism (Wu and Huan, 2011).After further comparison of the TLR of vertebrates, they determined that another combination occurred between the TIR and LRR during the evolution of primates (Wu and Huan, 2011). They believe that this second combination gave rise to our present TLR, which has the capability of signaling the innate and alerting the adaptive immune system. The innate immune system is the oldest defense system. Because of this, the earliest form of the innate immune system of simple organisms, such as cnidarians, are closely related to vertebrates, such as people.As organisms moved from water to land, they encountered more types of pathogens. Pressure from pathogens caused many or ganisms to develop an innate memory that is more expansive. However, as organisms became more complex, the innate memory did not adequately protect the organism. The inadequacy of the innate immune system leads to the formation of the adaptive immune system. Evolution of the adaptive immune system and the adaptive memory The adaptive memory is different from the innate memory because the receptors in the adaptive memory begin life with a blank memory.There are two major types of lymphocyte receptors that play an important role in the adaptive memory: B cell and T cell. It is hypothesized that B cell receptors (BCRs) and T cell receptors (TCRs) have a common ancestor (Flanjnik et al. 2010). The characteristics of these genes are discovered in gnathostomes, but not in agnatha. These characteristics include being able to have large amount of cells for differentiation. This finding caused scientists to create a theory called the ‘big bang theory’ of adaptive immune system ( AIS) emergence.The finding also prompted scientists to examine the changes of these receptors’ characteristics from gnathostomes to mammals. These finding lead scientists to determine the origin and evolution of the adaptive immune system. Figure 2: A summary of the immunoglobulin’s structures and functions found in gnathostomes to mammals. The first receptor that researchers focused on was the B cell receptors. Immunoglobulin M (IgM) is a B cell receptor that has the same function in all organisms starting from the gnathostomes (Flajnik and Hasahara, 2009). Some of these functions include having its transmembrane form defining the B cells.In humans, IgM is responsible for increasing the complement activation during the interaction of antigens and lymphocytes. This characteristic caused the IgM to be very efficient at causing lysis in microorganisms. IgM also causes clumping of pathogens. The clumping of pathogens was discovered in bony fish, while the increasing of th e complement activation was found in cartilaginous fish. This showed that although the function of IgM did not change, it was altered as organisms became more complex. Immunoglobulin D (IgD) is another B cell receptor.IgD is different from IgM because although both humans and bony fish have IgD, IgD in humans is attached to the surface of basophils, while in bony fish, the IgD is attached to granulocytes’ surface (Flajnik and Hasahara, 2009). Although the function of IgD is still unknown, the finding of IgD at two different locations indicates that there are possible changes in its functionality. The only vertebrates that do not have IgD are birds. These findings support the idea that like IgM, IgD is an old antibody class that has changed its function from gnathostomes to mammals. Amphibians have a B cell receptor known as IgY.Mammals have IgG, IgE, and IgA B cell receptors. Mammals obtained IgG and IgE through the alternative splicing of IgY. IgG has the same function as Ig Y. IgE’s function is different from IgG because it is responsible for releasing various pharmacological mediators, while IgG’s function is to activate complement when reacting with an antigen. IgA is found in reptiles. The discovery of IgE, IgG, and IgA in mammals reinforces the idea that as organisms became more complex the type of immunoglobulin receptors increased, thus making the adaptive immune system more complex. Like BCRs, some TCRs had a similar situation. ? T cell receptors from jawed fish to mammals have the same function. ? T cell receptors in both sharks and marsupials are structurally the same. Both sharks and marsupials have three domain receptor chain with two amino-terminal V domains and a membrane-proximal C domain. However, the formation of the V domains and C domains are different for sharks and marsupials. The V domain for sharks is made from VDJ rearrangement, while the V domain for marsupials is generated by one set of V, D and J segments of a pr e-rearranged VDJ gene. The function of these receptors has not been reported.The difference in the formation of the V domain indicates that due to pressure from the environment, part of the adaptive immune system underwent evolution to meet the needs of marsupials. Examining the change of the receptors from the gnathostomes to mammals has shown that the adaptive immune system underwent change as organisms became more complex. However, this does not illustrate how the adaptive immune system formed. The recombination-activating gene (RAG) transposon and the whole-genome duplication are the two events that brought about the adaptive immune system (Flajnik and Hasahara, 2009).RAG encodes enzymes that impact the rearrangement of T cell receptors and immunoglobulin. There are two main types of RAG in vertebrate immune system: RAG-1 and RAG-2. These two types of RAGs play a major role in the formation of immunoglobulin superfamily (IgSF). During the 1970s, two Japanese researchers discover ed that recombination signal sequences (RSSs) were flanked by V,D, and J rearranging segments. These segments within the RSSs had repeats that were reminiscent of a transposon. From this, they reasoned that a transposon invaded IgSF (Flajnik and Hasahara, 2009).The invasion resulted in IgSF not being able to function unless through recombinase. Flajnik and Hasahara believed that IgSF genes were invaded by the RAG transposons. Researchers could not obtain all RAG genes from agnatha, but they were able to obtain it from gnathostomes. This indicates that the RAG transposon plays a role in triggering IgSF (Flajnik and Hasahara, 2009). The invasion of the genome by the transposon was vital for the adaptive immunity system because it gave rise to BCR and TCR, which are part of the IgSF and both play a major role in the adaptive immune system.The occurrence of whole genome duplication also plays a role in the formation of the vertebrate adaptive immune system. Susumu Ohrno was the first re searcher to propose the idea that the vertebrate genome underwent two rounds of whole gene duplication (WGD), which occurred after the emergence of the jawed vertebrates. WGD is an event that creates an organism with additional copies of the entire genome. At first, this idea was met with great skepticism but scientists now accept the idea because many ohnologues are essential components of the jawed ertebrate adaptive immune system. Ohnologues are paralogues that are close to the origin of vertebrates through whole-genome duplication (Flajnik and Hasahara, 2009). Understanding what influences the evolution of the adaptive memory is also important in understanding the evolution of the adaptive memory. There are many speculations on why the adaptive immune system is developed. Some reasoned that because the innate immune system was inefficient and difficult to regulate, it lead to the development of the adaptive immune system.Pressure from pathogens and the ability to have few offspr ing also caused natural selection to favor the formation of an adaptive immune system (Flajnik and Hasahara, 2009). For instance, organisms such as seahorses live in an environment that has few pathogens that will threaten its livelihood. In addition, seahorses produce large amount of offspring. Because there are not many pathogens that a seahorse encounters, the innate immune system is adequate in dealing with the few pathogens. Organisms such as sharks are predators, and many produce few offspring during their lifetime.This pressurizes sharks to have an adaptive immune system because the offspring will have the ability to combat pathogens of all types. Sharks adaptive immune system is not as complex as vertebrates that dwell on land because water does not contain as many pathogens as compared to land. Mazmamian of California Institute of Technology recently conducted a research that indicated that microbiota had a larger influence on the evolution of the adaptive immune system tha n pathogens’ influence (Lee et al. , 2012). Microbiota have a symbiotic relationship with the body.An example of this occurs with bacteria located in the gut. A function of these bacteria is that they help food move quickly through the body. Researchers have discovered that the microbiota, which includes bacteria and viruses, have many different antigens. This provides the adaptive immune system and the microbiota with a challenge because the immune system must either react toward or ignore the foreign antigen (Lee et al. , 2012). In order to prevent overreaction from both parties, both the adaptive immune system and the microbiota develop tolerance through the expansion of regulatory T cell (Lee et al. , 2012).Scientists speculated that this symbiotic relationship between vertebrates and microbiota could have influenced the adaptive memory because symbiotic microbiota could have pressured vertebrates to develop the current adaptive immune system that have developed tolerance to bacteria that is good for the body (Lee et al. , 2012). Current research applications Edward Jenner was the first to start experimenting with vaccines. Afterwards, research on vaccines became more complex. Vaccine researches now include the study of the pathogens and virus’ immune system. Mycobacterium tuberculosis and human immunodeficiency virus.One of the most studied pathogens is the Mycobacterium tuberculosis. Currently, there are two standard strategies to combat Mycobacterium tuberculosis. The first strategy involves identifying the protein that is produced by the bacterium that is essential to its virulence (Flynn, 2004). Once the protein is identified, the immune system can neutralize the protein. This will result in the bacteria not being infectious to the body. This strategy cannot be applied to Mycobacterium tuberculosis because although there is ongoing research, scientists have not been able to identify the protein that causes its virulence (Flynn, 2004).Myc obacterium tuberculosis’ main virulence is its ability to survive within macrophages. The second strategy is to use an attenuated form of the pathogen, which will cause an effective immune response, but will not cause disease. The second strategy involves the adaptive memory immune system because the vaccine is causing the adaptive memory to remember the pathogens that is similar to Mycobacterium tuberculosis. Currently, the second strategy is implemented through the vaccine Bacillus Calmette-Guerin (BCG) (Flynn, 2004). BCG is used by 4 million people around the world (Flynn, 2004).Although BCG is the most commonly used vaccine to treat tuberculosis, it is still not effective because the vaccine can only prevent tuberculosis only in children, but not in adults. Researchers are now investigating the immune response to M. tuberculosis in order to create more effective vaccines. Current research involves injecting patients with the cytokine interleukin 12 (IL-12) (Flynn, 2004). Il-12 plays an important role in controlling M. tuberculosis infection. Studies have shown that when mice are injected with the Il-12 DNA, the amount of bacterial numbers of M. tuberculosis is greatly reduced.Tumor necrosis factors ? (TNF-? ) and interferon-gamma (IFN-? ) are important cytokines that play an important role in combating M. tuberculosis. IFN-? is a central cytokine in control of M. tuberculosis because it activates the macrophages to attack M. tuberculosis (Flynn, 2004). Organisms with defective IFN-? are more susceptible to infections. TNF-? is important because in synergy with INF-? , it leads to the formation of nitrogen oxide synthase 2 (NOS2) (Flynn, 2004). Although NOS2’s role is not clearly known, it is shown that when organisms were under the infection of M. uberculosis, NOS2 expression was low (Flynn, 2004). This indicates that a high expression of TNF-? , IFN-? , and NOS2 can cause the body to fend off tuberculosis. It is known that overexpression of TNF-? can also cause harm to the body by increasing the chance of getting tuberculosis (Flynn, 2004). As a result, researchers are now conducting vaccine research on how to create the right amount of expression of the three cytokines that allow the immune system to effectively combat M. tuberculosis. The human immunodeficiency virus (HIV) is another area targeted for vaccine research.Currently, there are three vaccines approaches in creating a vaccine that targets the HIV-1 protease (McMichael et al. , 2009). HIV protease is an important aspect of the HIV life cycle. All of these methods have failed. Scientists are now proposing to use less empirical approach and to focus more on understanding the immune response to HIV-1 infections when producing new vaccines (McMichael et al. , 2009). During an HIV infection, natural killer cells (NK) become activated. NK cells have the ability to control HIV replication through cytolysis of the infected cells.NK cells also have the capacity to in fluence T cell responses (McMichael et al. , 2009). HIV-1 has responded by reducing its receptors, making it harder for the NK cells to detect the infected cells. Current research is focused on priming the antiviral activity of the NK cells through vaccination. Researchers are cautious when activating the innate immune system because the innate immune response can be harmful because the activation of the innate immune system produces pro-inflammatory cytokines and chemokines, which can promote the HIV-1 replication (McMichael et al. , 2009).As a result, the vaccine-induced activation of the innate immune system must be thoroughly tested and used with caution. Conclusion There are many laboratories around the world conducting research on creating an effective vaccine to target the different diseases that people combat every day. Although this strategy is new, implementing a research strategy that focuses more on the immune system when creating vaccines will allow the vaccine to be mo re effective. In addition, implementing this strategy requires deep understanding of the mechanism and evolution of both the innate and adaptive immune systems.Both the innate and adaptive immune system evolve from being able to perform simple tasks in primitive organisms to perform complex tasks in complex organisms, such as humans. Therefore, in order to create a vaccine, it is vital to start from simple organisms. Once that is accomplished, one can build on top of the newly developed vaccine that targets more complex organisms and combat the superbug carbapenem-resistant enterobacteriaceae. Literature Cited 1. Flajnik and Hasahara, Martin F. , and Masanori Kasahara. â€Å"Origin and Evolution of the Adaptive Immune System: Genetic Events and Selective Pressures. Nature Reviews Genetics 11. 1 (2009): 47-59. Print. 2. Flynn, JoAnne L. â€Å"Immunology of Tuberculosis and Implications in Vaccine Development. † Tuberculosis 84. 1-2 (2004): 93-101. Print 3. Kurtz, Joachim. â⠂¬Å"Memory in the Innate and Adaptive Immune Systems. † Microbes and Infection 6. 15 (2004): 1410-417. Print 4. Lee, Yun Kyung, and Sarkis K. Mazmanian. â€Å"Has the Microbiota Played a Critical Role in the Evolution of the Adaptive Immune System? † Science 330 (2012): 1768-773. Print. Kurtz, Joachim. 5. McMichael, Andrew J. , Persephone Borrow, Georgia D.Tomaras, Nilu Goonetilleke, and Barton F. Haynes. â€Å"The Immune Response during Acute HIV-1 Infection: Clues for Vaccine Development. † Nature Reviews Immunology 10. 1 (2009): 11-23. Print. 6. Sompayrac, Lauren. How the Immune System Works. Malden, MA: Blackwell Pub. , 2008. Print 7. USA TODAY. â€Å"CDC Sounds Alarm on Deadly, Untreatable Superbugs. † USA TODAY. N. p. , 5 Mar. 2013. Web. 23 Mar. 2013. 8. Wu, Baojun, and Tianxiao Huan. â€Å"Domain Combination of the Vertebrate-like TLR Gene Family: Implications for Their Origin and Evolution. † Journal of Genetics 90. 3 (2011): 401-08. Print

Unix Multiprogramming

The computer allocated in UNIX to every process, whether a system task or user task. The choice of task to be executed when the CPU becomes free is based on a formula that penalizes tasks that have used most CPU cycles in the recent past. The process priority which can be set by super user (root) is an important part of this formula. The CPU scheduling algorithm is simple but allows users some measure of control over their workstation performance. The CPU speed defines the capacity of a mainframe for a given release of the operating system. All other hardware components are usually configured so that when the system is fully loaded, the CPU which is by far the most expensive resource becomes the bottleneck. In order to give the user the impression of simultaneous execution, the CPU must be allocated alternatively among the individuals processors. This task is managed by scheduler, a special processor that maintains a list of normal processes and sees to it that the processor handles the next process at certain time intervals. There are various strategies that a scheduler can use to determine which process to handle next, one of these strategies is (round robin) selects the next respective process in the list at regular intervals and puts it at the end of the list after the allocated time if the process is not yet finished. Another strategy assigns each process a priority, whereby processes with higher priority are allocated more CPU time. UNIX employs nice levels, which allow the user to influence the internal priorities of processes. This allows the user to reduce significantly the encumbering of the system by programs running in the background. Likewise the administrator can also raise the priority of important process to ensure faster execution. UNIX does timesharing as well as multiprogramming. Timesharing creates the illusion that several processes execute simultaneously, even though there maybe only one physical CPU.

The Hidden Power of Media Discourse and the Capacity of...

ASSIGNMENT 5 â€Å"The hidden power of media discourse and the capacity of the capitalist class and other power-holders to exercise this power depend on systematic tendencies in news reporting and other media activities† (Page 25). Explain and exemplify. Zulfiqar Ahmad ID # 4025 Submitted to: Dr. M. Umer Farooq 1. Introduction Hidden power, according to Fairclough (1995a), is the â€Å"power behind discourse† and entails how and to what extent the holders of powers exercise their influence. Discourse being a social practice (Fairclough 2001) and an element of a communicative event (van Dijk 1997) becomes a strong determinant that impacts culture and distributes power in society. This approach to discourse makes media a†¦show more content†¦It not only signals the topic of the report but also serves cognitive and ideological functions (van Dijk 1988a, 1988b, 1991 quoted by Kuo and Nakamura 2005). Van Dijk (1991) has found the theme as biased by the reporter or editor’s subjectivity. They attempt to naturalize the opinion by manipulating the contents of the report. 2.1.2. Lexical options Lexical options refer to the selection and use of words that give clues to the reader that might be used in the interpretation of the events. Lexical items are most of the time evaluative words or expressions, slangs, labeling phrases, and words with strong connotations and collocations. 2.1.3. The use of quotation Quotations are context and source bound and their frequency varies from one culture to another. Quotations appear in different patterns such eyewitness reports, specialist knowledge, statements of police, lawyers or judges, etc. preference is given to political, legal, and bureaucratic account of events to the discourse of powerless such as the victims or delinquents. 2.1.4. Transitivity Transitivity is the base of representation with the potential to interpret the event from different foci (Fowler 1991). The choice of voice or use of nominalization hints at the perceptions of the producers and the interpreters. 3. Media Discourse: News Reports and News Production All forms of printed text, especially those of the mass media are mostShow MoreRelated Erica Carter - Young Women and their Relationship to Consumerism4438 Words   |  18 Pagesfeminist critique. Carter insists that the image industries are acutely aware of gender difference which operates as a dominant variable for the construction of consumer groups. She takes the youth subculture theorists to task for not recognizing this. In this case, she focuses on the female consumer in post-war (West) Germany (Gray and McGuigan, 1997, p. 92). 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