Cell Biology: Organelles, Membranes, Transport, and Cell Division, Summaries of Animal Anatomy and Physiology

Download Cell Biology: Organelles, Membranes, Transport, and Cell Division and more Summaries Animal Anatomy and Physiology in PDF only on Docsity! PANAY, MAIKA A. BSN 1-A ANAPHY 1. Define cytoplasm and organelles. -Cytoplasm is the cellular material outside the nucleus and inside the plasma membrane. It is the site of most cellular activities, so you might think of the cytoplasm as the “factory floor” of the cell. - While the organelles are specialized cellular compartments that are the metabolic machinery of the cell. Each type of organelle is specialized to carry out a specific function for the cell as a whole, much like the organs carry out specialized functions for the whole body. 2. List the functions of the cell. - Cell metabolism and energy use. The chemical reactions that occur within cells are collectively called cell metabolism. -Synthesis of molecules. Cells synthesize various types of molecules, including protiens, nucleic acids, and lipids. - Communication. Cells produce receive and chemical and electrical signals that allow them to communicate with one another. - Reproduction and inheritance. Each cell contains a copy of the genetic information of the individual. 3. Describe the structure of the cell membrane. What function does it perform? - Cell membrane or plasma is the outermost components of the cell. The cell membrane encloses the cytoplasm and forms the boundary between material inside the cell and material outside it. Substances outside the cell are called extracellular substances, and those inside the cell are called intracellular substances. Besides, enclosing the cell, the cell membrane supports the cell contents, acts as selective barrier that determines what moves into and out of the cell, and plays a role in communication between the cell. Cell membranes are selectively permeable, they allow some substances, but not others, to pass into or out of the cells. 4. Define solution, solute, solvent, diffusion and concentration gradient - Solution, is a homogeneous mixture of two or more components. - Solute, are components or substances present in smaller amounts. - Solvent, is the substance present in the largest amount in a solution. - Diffusion, is the process by which molecules and ions move away from areas where they are more concentrated, more numerous to areas where they are less concentrated with fewer of them. -Concentration gradient, is the difference in the concentration of a solute of a solvent between two points divided by the distance between the two points. The concentration gradient is said to be steeper when the concentration difference is large and/or the distance is small. 5. How do lipid-soluble molecules, small molecules that are not lipid-soluble and large molecules that are not lipid-soluble cross the cell membrane? - Lipid-soluble molecules and some small molecules can permeate the membrane, but the lipid bilayer effectively repels the many large, water-soluble molecules and electrically charged ions that the cell must import or export in order to live. Transport of these vital substances is carried out by certain classes of intrinsic proteins that form a variety of transport systems: some are open channels, which allow ions to diffuse directly into the cell; others are facilitators, which, through a little-understood chemical transformation, help solutes diffuse past the lipid screen; yet others are pumps, which force solutes through the membrane when they are not concentrated enough to diffuse spontaneously. Particles too large to be diffused or pumped are often swallowed or disgorged whole by an opening and closing of the membrane. 6. Define osmosis and osmotic pressure - Osmosis is diffusion of water across a selectively permeable membrane, such as the cell membrane, from a region of higher water concentration to one of lower water concentration. - Osmotic pressure is the forced required to prevent the movement of water across a selectively permeable membrane. Thus, osmotic pressure is the measure of the tendency of water to move by osmosis across a selectively permeable membrane. 7. What happens to cells that are placed in isotonic solution? Hypertonic or hypotonic solutions? What are crenation and lysis? - When a cell is placed in an Isotonic solution water moves into and out of the cell at the same rate. No net water movement occurs, and the cell shape remains normal. - When a cell is placed in a Hypertonic solution, water moves by osmosis out of the cell and into the solution, resulting in shrinkage. - When a cell is placed in a Hypotonic solution, water enters the cell by the osmosis, causing the cell to swell or even burst. - Crenation is the resulting in shrinkage and the lysis is the puff of red in the lower part of cell. 8. What is carrier-mediated transport? Howare facilitated diffusion and active transport similar and howare they different? - Carrier-mediated transport is which move large, water-soluble molecules or electrically charged ions across the cell membrane. A molecule to be transported binds to a specific carrier molecule on one side of the membrane. - Facilitated diffusion is a carrier-mediated transport process that moves substances across the cell membrane from an area of higher concentration to an area of lower concentration of the substance. Because movement is with the concentration gradient, metabolic energy in the form of ATP is not required. - Active Transport is a carrier-mediated process that moves substances across the cell membrane from regions of lower concentration to those of higher concentration against a concentration gradient. Consequently, active transport process accumulates substances on one side of the cell membrane at concentrations many times greater than those on the other side. - Microfilaments are small fibrils formed from protein subunits that structurally support the cytoplasm. Some microfilaments in muscle cells enable the cells to shorten or contract. - Intermediate filament are fibrils formed from protein subunits that are smaller in diameter than microtubules but larger in diameter than microfilaments. They provide mechanical support to the cell. 19. Describe the structure and function of centrioles. - Centrioles are paired cylindrical bodies, each composed of nine triplets of microtubules. Organize a microtubule network during mitosis (cell division) to form the spindle and asters. Form the bases of cilia and flagella. 20. Describe the structure and function of the cilia, flagella and microvilli. - Cilia are whiplike cellular extensions that move substances along the cell surface. Typically, in large numbers, on the exposed surfaces of certain cells. When a cell is about to form cilia the centrioles multiply and line up beneath the plasma membrane at the cell's free surface. - Flagella have a structure similar to that cilia but are much greater, and they usually occur only one per cell. Sperm cells each have one flagellum, which propels the sperm cells. - Microvilli are tiny, fingerlike extensions of the plasma membrane that project from an exposed cell surface. They increase the cell’s surface area tremendously and so are usually found on the surface of cells active in absorption such as intestinal and kidney tubule cells. 21. Describe how proteins are synthesized and how the structure of DNA determines the structure of proteins. - DNA serves as the master blueprint for protein synthesis. Although cells also make lipids and carbohydrates, DNA does not dictate their structure. DNA is specified only the structure of protein molecules, including the enzymes that catalyze the synthesis of all classes of biological molecules. 22. Define autosome, sex chromosome and diploid number. - Autosome has 22 pairs of chromosomes - Sex chromosomes has 1 pair which consist 2 X chromosomes - Diploid number has 46 chromosomes and are organized to form 23 pairs of chromosomes. 23. How do the sex chromosomes of males and females differ? - The difference of chromosomes between male and female are X chromosomes for females and a Y chromosome for male. 24. Describe what happens during interphase and each stage of mitosis? What kinds of cells undergo mitosis? - Prophase, during prophase the chromatin condenses to form visible chromosomes. - Metaphase, in metaphase the chromosomes align near the center of the cell. - Anaphase, the beginning of anaphase the chromatids separate. When this happens, each chromatid is then called a chromosome. - Telophase, during telophase the chromosomes in each of the daughter cells become organized to form two separate nuclei. - Following the telophase, cytoplasm division is completed, and two separate daughter cells are produced. 25. Define cell differentiation. In general terms, how does differentiation occur? -Cell differentiation is a sperm cell and an oocyte unite to form a single cell, and a new individual begins. The single cell formed during fertilization divides by mitosis to form two cells, which divide to form four cells and so on. During differentiation of a cell, some portions of DNA are active, but others ae inactive. The active and inactive sections of DNA differ with each cell type. 26.List the principal hypothesis of aging. - Cellular clock. It is one hypothesis of aging suggests the existence of a cellular clock that, after a certain passage of time or a certain number of cell division. - Death genes. Another hypothesis suggests that there are “death genes”, which turn on late in life, or sometimes prematurely, causing cells to deteriorate and die. - DNA damage. Is another hypothesis suggest that, through time, DNA is damage, resulting in cell degeneration and death. - Free radicals. DNA is also susceptible to direct damage, resulting in mutations that may result in cellular dysfunction and ultimately cell death. - Last is Mitochondrial damage. Mitochondrial DNA may be more sensitive to free-radical damage than is nuclear DNA. Mitochondrial damage may result in loss of protiens critical to mitochondrial function.