Ch.+3+Notes.docx

Ch. 3 The Cellular Level of Organization Define the following terms Sex cells = made up of sperm and egg Somatic cells = body cells or somatic cells, all other cells The cell can be divided into three principal parts Plasma membrane = is a flexible, sturdy barrier that surrounds and contains the cyt...

Ch. 3 The Cellular Level of Organization Define the following terms Sex cells = made up of sperm and egg Somatic cells = body cells or somatic cells, all other cells The cell can be divided into three principal parts Plasma membrane = is a flexible, sturdy barrier that surrounds and contains the cytoplasm of the cell, membrane consists of protein in a sea of lipids Structure of Plasma Membrane Lipid bilayer is the basic framework of plasma membrane and is made up of 3 types of lipid molecules: phospholipids, cholesterol, and glycolipids Phospholipid bilayer = phospholipid molecules form two layers, one phosphate and 2 fatty acids Membrane proteins = makes 55 percent of weight of plasma membrane Integral protein = part of the plasma membrane structure and cannot be easily separated Peripheral protein = bound to inner surface or outer surface of plasma membrane Recognition Protein = cells of immune system recognize other cells as normal or abnormal Receptor protein = sensitive to presence of specific extracellular ions or molecules called ligands Carrier protein = binds solutes and transport them across plasma membrane Channel = central pore that forms a passageway completely through plasma membrane, gated channels they can open or close to regulate passage of substances Function of Plasma membrane Physical isolation = separates inside of cells from surrounding extracellular fluid Regulation of Exchange with the Environment = controls entry of ions and nutrients, eliminates wastes and release secretion Sensitivity to the Environment = contains receptors, allow cells to recognize and respond to specific molecules in its environment Structural support = gives tissues stability Selectively permeable = meaning that some things can pass through and other cannot Cytoplasm = material between plasma membrane and membrane that surrounds nucleus Cytosol = also known as intracellular fluid, is composed mostly of water, plus proteins, carbohydrates, lipids, and inorganic substances Cytoskeleton = network of protein filaments that extends throughout cytosol, several kinds of protein filaments that extend throughout cytoplasm and provides structural framework for cell Intermediate filament function is to support and to help anchor organelles such as the nucleus Microfilament function in movement and mechanical support Microtubules help determine cell shape and function in intracellular transport of organelles and migration of chromosomes during cell division Extracellular = watery medium that surrounds cells Intracellular = fluid inside the cell, the cytosol Organelles =” little organs” internal structures of cells that perform most of tasks that keeps cell alive and functioning Centrioles = during cell division, aid in formation of spindle apparatus needed for movement of chromosomes, not found in red blood cells, skeletal muscles cells, cardiac muscle cells and typical neurons Centrosome = region of cytoplasm located next to nucleus in cell, it is microtubule organizing center of centrioles for animal cells Ribosomes = organelles responsible for protein synthesis, two types Free ribosomes = scattered throughout cytoplasm Fixed ribosomes = attach to endoplasmic reticulum Golgi apparatus = principle function is to process, sort, and deliver proteins and lipids to the plasma membrane, lysosomes, and secretory vesicles Golgi vesicles = deliver proteins to plasma membrane, where they are discharged by exocytosis into extracellular fluid Lysosomes = contain digestive enzymes that break organic polymers into monomers, remove damaged organelles, destroy bacteria, and cleanup and recycles inside cell. Tay-Sachs disease, disorder caused by faulty lysosomes, affect children of Eastern European Jewish, lacks enzyme that breaks down membrane glycolipid called ganglioside, found in nerve cells. Excessive ganglioside accumulation does not let nerve cell function efficiently, experience seizures and muscle rigidity, gradually become blind, demented, usually die before age of 5. Proteasomes = job is to remove proteins from cytoplasm, destroy unneeded, damaged, or faulty proteins, they have protein digestive enzymes or proteases, which cut proteins into small peptides Peroxisomes = absorbs and break down fatty acids and other organic compounds, they generate hydrogen peroxide, (H2O2), it has enzyme called catalase. Protects cell from potentially damaging effects of free radicals produced during catabolism Mitochondria = produce energy to carry out functions of life, site of ATP production in the cell by the catabolism of nutrient molecules, have their own DNA Rough Endoplasmic Reticulum = site of protein synthesis, produces secretory proteins, membrane proteins, and many organellar proteins Smooth Endoplasmic Reticulum = synthesize fatty acids, steroids, in liver cells helps release glucose into bloodstream, inactivate or detoxify lipid-soluble drugs or potentially harmful substances, such as alcohol, pesticides or carcinogens Drug tolerance = prolonged use of drugs such as phenobarbital, develop changes in smooth ER of the liver, it increases tolerance of drug, Smooth ER increase production of its enzymes to protect the cell from its toxic effect Cilia = fairly long, slender extensions of plasma membrane, two types Primary cilium = non-motile acts as single sensor, detecting environmental stimuli and coordinate as homeostasis at tissue level Motile cilia = found in respiratory and reproductive system, they have a “beat” rhythmically to move fluids or secretions across cell surface. Tobacco = the movement of cilia is paralyzed by nicotine, smokers cough often to remove foreign particles from their airways Flagella = whip like extension of plasma membrane, found in sperm, moves the entire cell Microvilli = greatly increase surface area of cell exposed to extracellular environment Nucleus = control center for cellular operations, determines structure of cell and what functions it can perform by controlling which proteins are synthesized Nuclear envelope = chemical communication between nucleus and cytoplasm takes place through openings in nuclear envelope called nuclear pore Nucleoli = synthesize ribosomal RNA Chromatin = DNA content of nucleus when chromosomes are uncoiled Chromosomes = dense structures composed of tightly coiled DNA strands Genes = cell’s hereditary units, which are arranged in single file along chromosomes Human body (somatic) cells have 46 chromosomes arranged in 23 pairs Low Density Lipoprotein LDL = it takes cholesterol to your arteries, where it may collect in artery walls. Too much cholesterol in your arteries may lead to a buildup of plaque known as atherosclerosis, This can increase the risk of blood clots in your arteries. If a blood clot breaks away and blocks an artery in your heart or brain, you may have a stroke or heart attack. High Density Lipoprotein HDL = “good cholesterol” because it transports cholesterol to your liver to be expelled from your body. HDL helps rid your body of excess cholesterol so it’s less likely to end up in your arteries. Protein Synthesis much of the cellular machinery is devoted to synthesizing large numbers of diverse proteins Proteins determine physical and chemical characteristics of cells Instructions for protein synthesis is found in DNA in nucleus Protein synthesis involves transcription and translation Transcription process by which genetic information encoded in DNA is copied onto strand of RNA called messenger RNA (mRNA) directs protein synthesis. It alos synthesizes ribosomal RNA (rRNA) where translation takes place transfer RNA (tRNA) brings additional amino acids, utilizing binding affinity with its anticodon region Translation process of reading mRNA nucleotide sequence to determine amino acids sequence of protein Transport across the plasma membrane Process to move substances across the cell membrane essential to the life of the cell Passive processes = require no energy, simple diffusion, facilitated diffusion, osmosis and are driven by concentration gradients Active processes = include active transport and vesicular transport, and these require cellular energy Passive processes Diffusion = the movement of a substance from an area of higher concentration to an area of lower concentration Simple diffusion = molecules diffuse through lipid proteins of the membrane, example fatty acids, steroids, dissolved gases Channel-Mediated Diffusion = small passageways created by transmembrane proteins, Osmosis = movement of water across a selectively permeable membrane from one solution to another solution that contains higher solute concentration Hypertonic = a solution with a higher solute concentration than of the cell Hypotonic = a solution with solute concentration lower than of the cell Isotonic = no osmotic flow takes place and the size and shape of cell look normal Facilitated diffusion = substance can be passively transported across membrane by carrier proteins, example glucose and amino acids into cell, no energy is needed, Type 1 Diabetes = An autoimmune disease that occurs when T cells attack and destroy most of the beta cells in the pancreas that are needed to produce insulin, so that the pancreas makes too little insulin (or no insulin). Type 2 Diabetes = Body either resists the effects of insulin, “insulin resistance” or does not produce enough insulin to maintain a normal glucose level Active processes Primary active transport = energy derived from ATP changes shape of a transport protein, pumps substance across plasma membrane against its concentration gradient Secondary active transport = energy stored in form of sodium or hydrogen ion concentration gradient is used to drive other substances against their own concentration gradients Endocytosis = extracellular materials are packaged in vesicles at cell surface and imported into cell Receptor-Mediated Endocytosis = highly selective process, produces vesicles that contain a specific target molecule in high concentrations Pinocytosis = brings extracellular (fluid)inside the cell, “cell drinking” Phagocytosis = brings solid from outside cell into the cell, “cell eating” Exocytosis = vesicle content are released into extracellular environment Cell division is process by which cells reproduce themselves Mitosis is increase in body cells is also referred to as somatic cell division Meiosis results in production of sperm and eggs, reproductive cell division Cytokinesis is cytoplasmic division The Cell Cycle in Somatic cells, orderly sequence of events by which cell duplicates its contents and divides in two Interphase = cell carries on every life process except division, consists of G1, S and G2 G1 phase = cell is metabolically active, duplicating its organelles and cytosolic components except DNA, very long time, cells destined never to divide again are said to be in GO phase S phase = chromosomes are replicated G2 = cell growth continues and cell completes its preparation for cell division Mitosis = distribution of two sets of chromosomes, stages are prophase, metaphase, anaphase and telophase Prophase = chromatin condenses and shortens into chromosomes, centrioles move to opposite poles, nuclear membrane disappears Metaphase = chromosomes line up at the equatorial plane region Anaphase = splitting of chromosomes and movement of two sister chromatids of each pair toward opposite poles of cell Telophase = identical sets of chromosomes at opposite poles of cell uncoil and revert to threadlike chromatin form, new nuclear membrane forms Cytokinesis = is division of cytoplasm and organelles, begins in late anaphase or early telophase Cancer is group of diseases characterized by uncontrolled cell growth, caner cells divide rapidly and ocntinuously Cells that divide without control develop into tumor or neoplasm Malignant tumor = ability to metastasis, spread of cancerous cells to other parts of body Metastasis = cancer cells an leave their site of origin and travel to other tissues or organs Benign tumor = does not spread to other parts of body Angiogenesis = growths of new networks of blood vessels Oncogenes = cancer causing genes Carcinogen = environment agent, chemical agent that produces cancer, induce mutation in DNA