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Essay / The cell: its work and the stages of life
(3) the amniOl:horionic membrane. Say no to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essay Honors Seminar in Biology Professor Scott January 11, 2018 Honors Research Paper in Biology The study of life, or biology, is a process that has been going on for thousands of years. Human interest in who we are and the world around us gave us the first explorers and information we have today. Fundamental principles from different biologists such as Charles Darwin about evolution help us dig and explore to push our human boundaries. Like many biologists, the ultimate goal of the article is to address how the cell differentiated, how it functions, the stages of life, and how it obtained genes. The cell is made up of different parts that serve as an organ of a body. These are parts called organelles. The cell wall is a rigid layer of material that surrounds the cell of plants and some other eukaryotes such as fungi. Its main purpose is to protect and support cells. For example, it helps plants from bursting their cell because there is a rigid wall to prevent this from happening, unlike most animals. The cell wall may be made of chitin for fungi and a stringy substance known as cellulose in plants. The chloroplast is found in photosynthetic plants and algae. Light-dependent photosynthesis relies on capturing sunlight for photosynthesis, while light-independent photosynthesis is the synthesis of new light to create glucose. The cell membrane is a selectively permeable membrane found in eukaryotic cells. The cell membrane allows diffusion, the movement of elements from high to low concentration. The three types of transport are passive, active and osmosis. Passive transport occurs when objects move with the concentration gradient, up and down. Simple passive transport occurs when molecules can easily slide through the phospholipid bilayer to reach their destination, either inside or outside. They also don't need ATP because they move with the concentration gradient. Small and uncharged molecules, as well as glucose, fatty acids, oxygen, carbon dioxide, and gases are some of the elements that can pass through simple passive transport. Facilitated passive transport is the transport of molecules from high to low concentration using protein channels and pumps. These molecules are generally larger and therefore the specifications to get to a certain area require assistance. The second type of transportation is active transportation. During active transport, ATP is used to move molecules against the concentration gradient, with molecules moving from low to high concentration. Usually, large, charged molecules (ions) need it. The only specialized pump in which this occurs is the ATP pump where opposite diffusion occurs. Finally, because water is necessary for the body to function, it can use pumps called aquaporins or simply be permeable through the cell membrane by simple diffusion. The latter is known as osmosis. Osmosis is the movement of solvent molecules like water across a semi-permeable membrane into an area of higher solute concentration like salt, toachieve homeostasis through the use of osmotic pressure to achieve an isotonic solution. The cytoplasm is the region between the cell membrane and the nucleus. It is a clear, thick, gel-like liquid that is constantly moving to facilitate different cellular processes. The two main processes of anaerobic respiration occur here. Glycolysis is the first form of respiration that occurs in the cell, in the cytoplasm. Glycolysis is the process that converts glucose, C6H12O6, to pyruvate, to produce 2 ATP. It can be both aerobic and anaerobic, resulting in approximately 2 ATP. Fermentation is a form of anaerobic respiration where only glucose is present. The products include gases, water and acids, but no ATP. Mitochondria are also another major generator of ATP energy of the cell.Two major respiratory processes that occur there are the Krebs cycle and the generation of energy via the electron transport chain (ETC). The Krebs cycle occurs in the matrix of mitochondria and breaks down pyruvate into carbon dioxide during extraction reactions. In total, the Krebs cycle produces approximately 1-2 ATP. The final stage of cellular respiration is the electron transport chain (ETC). The ETC is a series of molecules embedded in the mitochondrial membrane, it is the only process that produces most of the ATP needed. It occurs in the cristae of the mitochondria to convert the ADP remnants of the Krebs cycle into ATP. The electrons pass through different molecules until they finally react with oxygen and protons to form water. The result is approximately 32-34 ATP, water and carbon dioxide. The vacuole is a membrane-bound eukaryotic organelle that stores excess. is present in all plant and fungal cells and in certain protist, animal and bacterial cells. Vacuoles are essentially closed, water-filled compartments containing inorganic and organic molecules, including enzymes in solution, although in some cases they may contain solids that have been ingested. Vacuoles are formed by the fusion of several membrane vesicles and are actually just larger forms of them. The organelle has no basic shape or size; its structure varies depending on the needs of the cell. The nucleus holds the genetic key, called DNA, short for deoxyribonucleic acid. DNA contains the code for an entire cell. The nucleus houses the DNA because external conditions in the cytoplasm will destroy the DNA; thus, only different RNAs will leave the cell to carry out processes. DNA replication is the process by which DNA is copied to create two identical daughter pairs. The first step is for the DNA to unwind and separate using helicases, a protein that helps unwind the DNA; hydrogen bonds are broken. The second step is replication. The first step in replication is that the DNA splits into two strands, forming a Y-shaped formation known as replication fork replication. A matching half is necessary for the fork legs to fit and form a new pair of strands. One of the separated strands is called the leading strand, which is constantly used for DNA synthesis while the other strand is responsible for the synthesis of the leading strand. The third step is the linking of the corresponding bases to match the split DNA in order to compress them. Once replication reaches the end of the DNA strand, it terminates, leaving the replicated DNA. Both the nucleus and ribosomes are present in a process called protein synthesis. Protein synthesis is the process by which cells make the proteins they need.need. The first part of the process is known as transcription and takes place in the nucleus. The first DNA unwinds and unzips, breaking the hydrogen bonds. Thymine is replaced by uracil. The corresponding mRNA strand will bind to the two split DNA strands. and finally the mRNA will exit through the pores of the nucleus. The second part of the process is known as translation. It occurs in ribosomes that are located outside the free-floating nucleus or attached to the RER (rough endoplasmic reticulum). The mRNA resulting from transcription goes into the ribosome which itself has rRNA (ribosomal RNA). tRNA (transfer RNA) comes and translates 3 RNAs at a time, leaving behind one amino acid for each triple. The amino acids then link with peptide bonds forming a polypeptide chain. Finally, the chain folds into protein with the help of the Golgi apparatus and the RER. A cell is a singular and functional unit of an organism. Different types of cells have different types of organelles to carry out their essential life processes. The two types of cells that exist today are eukaryotic and prokaryotic cells. Prokaryotic cells are single-celled organisms that lack organelles or other membrane-bound units. The four main organelles present in prokaryotic cells are the plasma membrane(gateway), cytoplasm(transport+breathing), ribosomes(protein synthesis), and genetic material (like DNA and RNA). Eukaryotic cells, on the other hand, are unicellular or multicellular organisms that primarily possess specialized membrane-bound organelles. Examples of eukaryotic organelles would be the nucleus (a membrane-bound sac that contains the DNA that gives the controls), the chloroplast (a plant membrane-bound organelle that contains chlorophyll for photosynthesis), the lysosome (a animal membrane-bound organelle that breaks down excess and spent organelles with digestive acid...mini stomach), the vacuole (a membrane-bound organelle that stores excess nutrients, water and waste that has not left the cell) and mitochondria (a membrane-bound organelle that converts food into ATP energy). The similarities between eukaryotic and prokaryotic cells are that they have chromosomes/DNA/RNA, a plasma membrane, carry out a process of cell division (either mitosis, meiosis or binary fission) and carry out protein synthesis using ribosomes . The differences between prokaryotic and eukaryotic cells are that prokaryotic organelles are much simpler than eukaryotic organelles. Prokaryotic organelles include the cytoplasm (for travel), ribosomes (for protein synthesis), and a centralized DNA cluster but lacking any sort of membrane. Eukaryotic cells contain several membrane-bound organelles; the nucleus is a membrane that surrounds and protects DNA unlike prokaryotic plasmids, mitochondria are a double-membrane organelle that provides cellular respiration, and the chloroplast is a membrane-bound organelle for plants and plant protists that carry out photosynthesis with chlorophyll inside. The endosymbiont theory, which states that prokaryotes are other prokaryotes, and the autogenic theory, which states that prokaryotic cells fold up and begin to specialize into different cells, both support the fact that prokaryotic cells evolved much earlier and are simpler than eukaryotic cells. The four main eukaryotic groups are plants, animals, fungi and protists. Organisms in the animal kingdom are multicellular and do not have cell walls orphotosynthetic pigments. All organisms in the animal kingdom have some type of skeletal support and specialized cells. In addition, these organisms have cellular, tissue, organic and systemic organization. All organisms in the animal kingdom reproduce sexually rather than asexually. All land plants such as aquatic plants are found in the plant kingdom. Organisms in the plant kingdom produce energy through photosynthesis. Additionally, organisms in the plant kingdom have a cell wall and chlorophyll that capture light energy for photosynthesis, or the synthesis of light to produce glucose. The fungi kingdom is responsible for breaking down dead organic matter and helps recycle nutrients back into ecosystems. Additionally, the majority of vascular plants (plants with xylem-phloem systems) rely on symbiotic fungi to grow. For plants, symbiotic fungi are found in the roots of all vascular plants and provide them with important nutrients. For animals, fungi provide many types of medicines such as antibiotics and penicillin, but also cause many diseases. Fungal diseases are difficult to treat because fungi resemble organisms in the animal kingdom. Examples of fungal diseases include ringworm (a common fungal skin infection that often looks like a circular rash) and mucormycosis (a rare infection that primarily affects people with weakened immune systems). The last great kingdom of the eukaryotic domain is that of the protists. A protist is a eukaryotic organism that does not match the characteristics of animals, plants or fungi. The protist kingdom includes unicellular organisms. Organisms in the protist kingdom must live in an aquatic environment. The three types of organisms in the protist kingdom are protozoa, algae, and fungus-like protists. Protozoa obtain their food by phagocytosis, which involves engulfing their prey with structures. Algae contains chlorophyll and obtains its food through photosynthesis, just like plants. Fungus-like protists absorb nutrients from their environment directly into their cytoplasm (phagocytsis). Slime molds are an example of fungus-like protists that typically live in rotting wood. Malaria, a global disease that occurs in tropical climates, is caused by an animal-like protist known as Plasmodium. In the ocean, many plant protists live on the surface where they carry out photosynthesis. There are major similarities and differences between the eukaryotic kingdoms. Animals, plants, and fungi are eukaryotic and mostly multicellular, while protists are eukaryotic and unicellular. All except the animal kingdom can reproduce sexually and asexually, as they can only reproduce sexually using gametes. Plants can reproduce by asexual processes called budding and fragmentation and sexually by the use of gametes. Most fungi reproduce sexually through the use of gametes or asexually through fragmentation and budding. Finally, protists reproduce either sexually like animals and plants through the use of gametes, or asexually through binary fission. Plants and plant-related protists are autotrophic (meaning they make their own food to use for energy) while animals, fungi, andAnimal-like protists are heterotrophs (meaning they consume food to use for energy). Plants contain a cell wall made of cellulose, fungi contain a cell wall made of chitin, and some plant protists may contain a cell wall made of cellulose. The two main subcategories of eukaryotic cells are the classification of their cells as somatic or non-somatic cells, also called sex cells. Somatic cells are all cells in the body that are not used to reproduce. They contain 46 chromosomes or 23 pairs each in the human body, which constitutes a diploid cell. Examples of somatic cells include bone marrow cells, blood cells, brain cells, intestinal cells, etc. Sex cells, also called gametes or germ cells. Since they are used for reproduction, they are haploid. Being haploid means you have 23 chromosomes each, which ensures that a human is created by giving them a total of 46 chromosomes. Examples of sex cells include eggs and sperm. Most somatic cells reproduce through a process called mitosis. Mitosis is a process of nuclear division in eukaryotic cells that occurs when a parent cell divides to produce two identical daughter diploid cells. During cell division, mitosis specifically refers to the separation of duplicated genetic material carried into the nucleus. Meiosis, on the other hand, is a process that divides a cell into four haploid daughter cells, meaning they contain half the number of chromosomes of the diploid parent cell. Kingdoms that have both somatic and sexual cells are animals, plants, and fungi, as protists are only single cell and reproduce sexually through conjugation. Stem cells are unspecialized cells. The two types of stem cells are embryonic stem cells and adult stem cells. Embryonic stem cells are stem cells that have the ability to become anything they want, while adult stem cells only have the ability to be a certain type of cell. Embryonic stem cells are pluripotent, meaning they can become any stem cell they want. The cell differentiation process for stem cells begins when a division signal activates certain protein genes needed by the cell. The stem cell will then divide; half in a specific cell (like a blood cell) and the other half remaining in the niche. The appearance of a certain gene (such as the blood cell gene) on a cell corresponds to gene expression. Then, the signals emitted transform the divided cell into a fully specialized cell (like the blood cell). As new signals arrive, they multiply exponentially within the cell. To complete the transformation, most of the organelles and nucleus of the original stem cell are lost. The cell differentiation process is now complete and the new specialized cell will be sent to the area that needs it. This is the process by which a stem cell becomes a different cell, or the process of cell differentiation. The cell cycle is the cycle of cell division that takes place in the cell just before its division/reproduction as well as the reproduction of each new cell. using mitosis. The cell cycle is the period during which a new cell grows and carries out themitosis. Once a cell is made, it enters directly into the G1 phase, or synthesis phase, where rapid growth and metabolism occurs to expand the new cell---centrioles appear. The S phase, or synthesis phase, is where DNA replicates. Specific and precise DNA replication is necessary to prevent genetic abnormalities that often lead to cell death and disease. G2 or the second phase of growth matures the cell and the organelles are doubled so that it can enter the mitotic phase. In the M phase, or mitotic phase, the cell divides, leaving behind 2 diploid cells from the original diploid cell. The M phase itself included telophase, which forms a new DNA membrane around the daughter cell, and cytokinesis, which is the separation of the cytoplasm. Once cytokinesis is complete, the process of mitosis is complete. Different genes control the speed (how slow or fast) cellular reproduction occurs. After the signal, the proto-oncogene activates the cell cycle, thus accumulation of cells occurs over time. Too much of this can be a cause of cell buildup or tumors. Thus, another signal is sent to stop the accumulation; with genes known as tumor suppressors. Cell cycle balance is maintained by equal signaling between the two genes located at different sites or by the internal clock. The imbalance of these signals in cell formation is the cause of cancer. Cancer involves an uncontrolled cell that turns into a tumor and spreads throughout the body. Factors involved include exposure to chemicals, heredity in people with cancer, exposure to radiation and UV rays that cause skin cancer. All of these can mutate either the proto-onco gene or the tumor suppressor gene, resulting in abnormal amounts of cells. The two types of cell reproduction are mitosis and meiosis. Mitosis is a eukaryotic process that occurs in its somatic cells. Mitosis is a form of asexual reproduction that creates identical parent-daughter diploid cells. The ultimate goal is simple: create two diploid cells by separating the chromatids. The first phase of mitosis is interphase where a diploid (2n) cell grows and prepares to reproduce. Then, in prophase, the nuclear membrane dissolves and the copied chromosomes pair up. In metaphase, the chromosomes line up in the middle, at the equator of the cell, called the mitotic spindle. Then, in anaphase, the sister chromatids are separated into chromosomes and a different nuclear membrane begins to form. Finally, in telophase, the cell pinches off in the middle and two new diploid cells (2n) are formed as the cytoplasm is pinched off using the final process of mitosis called cytokinesis. The second process of cell production is called meiosis. It is used for the process of creating sex cells. The process of creating 4 haploid gametes is part I: separating the homologous pair and part II: separating the chromatids. In meiosis part I, interphase allows cells to grow so they can reproduce. At the prophase stage, the chromosomes are visible because the nuclear membrane has dissolved. Then, the chromosomes align in metaphase to form a homologous pair. In anaphase, the homologous pair separates and goes to either side. During cytokinesis and telophase, the cell divides in two, passing chromosomes from the homologous pair on one side while the other on the other side. This stage of being is like the beginning of mitosis and we must now separatethe chromatids. Since the cell is already developed, interphase is skipped and goes directly to prophase. In prophase II, the nuclear membrane is dissolved again. In metaphase II, the chromatids align in the middle. In anaphase II, sister chromatids are separated from the chromosomes and a different nuclear membrane begins to form. Finally, in telophase, the cell pinches off in the middle and four new haploid (n) cells are formed as the cytoplasm is pinched off using the final process of mitosis called cytokinesis. The products of meiosis contain half as many chromosomes in their cells as mitosis, because the products of meiosis (eggs and sperm) are then combined to form what is called a zygote (the first fertilized egg containing all the chromosomes necessary for growth). Meiosis, unlike mitosis, leads to character variations in one of four ways. The first way is to produce haploids. When making haploid cells, ? of mom's gene is added to? Dad's genes leading to different combinations of genes. The second method involves independent assortment that occurs during metaphase I. As midcells align for separation into different cells, the way they organize themselves during gamete manufacturing helps make so that a child becomes more like one of its parents or their equal. The shift into prophase can occur with any gene, making the possibilities endless. Finally, nondisjunction, when an extra chromosome goes to one side, can lead to different somatic/sex-linked disorders. Genes are made up of DNA, in a random assortment of patterns in the bases A, T, C, G coding for all the processes needed by the body (like the process of making different proteins). As your cells grow and duplicate, they pass this genetic information on to new cells. Each time DNA divides and is duplicated, they pass on a certain genetic code made possible by regular DNA replication or insertion, deletion, substitution and frameshifting. DNA is coiled to form structures called chromosomes. Most cells in the human body have 23 pairs of chromosomes, making a total of 46. However, individual sperm and eggs have only 23 (haploid) chromosomes. You received half of your chromosomes from your mother's egg and the other half from your father's sperm. A male child receives one X chromosome from his mother and one Y chromosome from his father; females receive one X chromosome from each parent. Genes are sections or segments of DNA carried on chromosomes that determine specific human characteristics, such as height or hair color. Because you have a pair of each chromosome, you have two copies of each gene (except for some genes on the X and Y chromosomes in boys, because boys only have one of each). A Mendelian gene is a gene that has a clearly defined dominant or recessive lineage. The genotype is either homozygous recessive in which the recessive appears and the dominant is not present, heterozygous in which the dominant appears although the recessive is present in the gene, and finally homozygous dominant in which the dominant appears and the recessive is not present. is not present. Cheek dimples are an example of a Mendelian trait in human cells. Cheek dimples are dominant while no cheek dimples are recessive. (C-cheek dimples, c-no cheek dimples) -With heterozygous parents. (75% chance of having dimples on the cheeks and.