Flashcards › A & P I Cells & Cell Metabolism

Who contributed to the cell theory? Matthias Schleiden, Theodor Schwan, and Rudolf Virchow What are two ways cells vary? In size and in shape What are some examples of how cells vary in shape? Nerve cells are long and threadlike for transmission; epithelial cells are thin, flat and tightly packed; and muscle cells are slender and rod-like What are the three major parts of a cell? Nucleus, cytoplasm, and cell (plasma) membrane What is the nucleus's nickname? "Control Center of Cell/Big Boss" What is the cell (plasma) membrane's nickname? "Gatekeeper of the Cell" What are the three main components of the plasma membrane? Phospholipids, proteins, and cholesterol What kind of heads and tails do the bilayer phospholipids have? Hydrophobic tails and hydrophilic heads. What does a receptor protein do? Turns cells on/off; receives information and communicates it to other parts of the cell. What does an integral/channel protein do? It transports; moves substances through membrane. What does a peripheral/marker protein do? It recognizes; marks "self" and identifies the cell. What are three types of intercellular junction? Tight junction, desomosome, gap junction. What is a tight junction? The membranes of adjacent cells are fused, such as with the small intestines. What is a desomosome? "Spot welds"; allow for stretching, as with the skin. What are gap junctions? Adjacent cells are connected by tubes that allow for ion and nutrient exchange, such as with muscle contractions and nerve impulse transmissions. What does "semipermeable/selectively permeable/differentially permeable" mean? Only selected substances are allowed to cross the cell membrane at specified times. What must be able to enter the cell where metabolism occurs? Nutrients, gases, and vitamins. What must be able to leave the cell after metabolism? Waste products. What are two categories of cell transport? Physical/Passive and Physiological/Active Which cell transport does NOT require energy? Passive What are some examples of physical/passive transport? diffusion, osmosis, facilitated diffusion, and filtration Which cell transport DOES require energy? Active/Physiological What are some examples of active/physiological transport? Active transport, endocytosis, and exocytosis What is diffusion? A movement of molecules from areas of high concentration to areas of low concentration. What are some characteristics of diffusion? The substances that are diffused across the cell membrane must be lipid soluble substances and dependent on random molecular motion. Where does diffusion occur, and what are some examples? In the lungs (gas exchange) and the cellular level (gas, waste, and nutrient exchange) What is facilitated diffusion? The movement of molecules from areas of high concentration to areas of low concentration with substances that are insoluble in the membrane, and must be assisted across by carrier molecules, such as channel proteins. What is osmosis? A special diffusion involving only water. What is a necessity of osmosis to keep the cell from swelling or shrinking? Must control the concentration of solute in body solutions. What is a substance that is being dissolved? Solute. What is a substance that is doing the dissolving? Solvent. What are three types of solutions? Hypertonic, Isotonic, and Hypotonic What is a hypertonic solution? A hypertonic solution has more solute particles than the cell or the solution to which it is being compared. What happens to the cell in a hypertonic solution? The cells shrink (crenate) in a hypertonic solution. What is an isotonic solution? An isotonic solution is a solution with the same amount of solute as the cell or another solution to which it is being compared. What happens to the cell in an isotonic solution? Cells remain the same size in an isotonic solution. What is an hypotonic solution? A hypotonic solution is a solution with a lesser amount of solute than the cell or another solution to which it is being compared. What happens to the cell in a hypotonic solution? Cells swell (cytolysis) in a hypotonic solution. What is filtration? Molecules forced through a membrane by hydrostatic pressure from areas of high concentration to areas of low concentration. What are some characteristics of active transport? Active transport is from an area of low concentration to an area of high concentration. It requires energy and involves a carrier molecule (protein). It allows the cell the ability to stockpile/store material inside the cell. What is endocytosis? The movement of large molecules to the inside of the cell. It includes invagination of the plasma membrane (vesicle forms). What are the two types of endocytosis? Phagocytosis and pinocytosis. What is phagocytosis? "Cell eating;" it is the intake of solid material, especially foreign material such as bacteria, splinters, pollen, or dead cells. What is pinocytosis? "Cell drinking;" it is the taking in of liquids with large dissolved molecules. What is exocytosis? Molecules are released to the outside of the cell. How many times does a cell enter the cell cycle? A cell enters the cell cycle approximately 50 times. How long does it take to complete the cell cycle? The cell cycle is a continous process that takes approximately 18-24 hours. The cell cycle is composed of two main divisions. What are they? Interphase and Mitosis/Cytokinesis Interphase takes up what percent of the cell life? 90% What are the three divisions of interphase, and what happens? G1 (gap 1; after cell division; replacing organelles), S (synthesis; DNA replication), G2 (gap 2; prepare to divide, produce enzymes) Describe the appearance of the cell during interphase. Normal cell with an intact nucleus, with no visible sign of cell division. "Resting cell." Chromatin are present. What are chromatin? Threadlike DNA material which can't be seen. What are the three parts of nucleotides? 5-carbon sugar (deoxyribose), phospate group, and a base What are the four bases of nucleotides? adenine, guanine, thymine, and cytosine How do the bases pair? According to Chargaff's Rules: adenine pairs with thymine, and guanine pairs with cytosine Who won the Nobel Prize for the discovery of teh structure of DNA? Watson and Crick Describe the appearance of a strand of DNA? A double helix, which looks like a twisted ladder. What are the strands of DNA actually made of? Two strands of nucleotides held together by hydrogen bonds with a sugar and phosphate backbone. Describe the steps in DNA replication. 1) Enzymes break hydrogen bonds between bases. 2) DNA helicase causes the DNA strand to unwind/unzip, exposing nucleotides. 3) Free nucleotides pair up to exposed nucleotiddes with DNA polymerase. 4) DNA ligase fills in gaps between new nucleotides. 5) DNA polymerase checks for mistakes. 6) The two resulting strands wind back up. What is the end result of replication? Each resulting strand is 1/2 parent and 1/2 new. What does karyokinesis mean? "Splitting of the nucleus." What are the four phases of mitosis? PMAT: prophase, metaphase, anaphase, and telophase What are some of the events that occur in prophase? Chromatin condense into chromosomes, which are then coiled. Chromosomes have two sister chromatids (copies) held together by a centromere. The centrioles migrate to teh opposite side of the nucleus. The nuclear envelope and nucleolus disappear. The spindle apparatus is assembled to move chromosomes. What are the three parts of the spindle apparatus? spindle fibers, centrioles, and asters What are some of the events that occur in metaphase? Centromeres of the chromosomes align along the equator. Spindle fibers attach to centromere. What are some of the events that occur in anaphase? Centromere releases sister chromatids. Chromatids become individual chromosomes. Chromosomes form to opposite poles as spindle fibers shorten. What are some of the events that occur in telophase? It is the opposite of prophase, so chromosomes return to chromatin (decondense), the nuclear envelope and the nucleolus reappear, and karyokinesis is complete. What is cytokinesis? Cytokinesis begins in late anaphase or early telophase. It is the dividing of the cytoplasm and the cell. A cleavage furrow, madeout of actin, forms then divides the cell into two. What is the end result of mitosis? Two daughter cells with exaclty the same DNA information. If a parent cell had 46 chromosomes the daughter cells each have? 46!!! What is cell differentiation? Even though all somatic (body) cells have teh same DNA information, they don't all function the same. In what week of gestation do cells begin to specialize in structures and perform specific functions? 3rd to 8th week What are some important factors that contribute to the rate of cell reproduction? cell size, hormones/growth factors, and space What happens when cell reproduction control is lost? Too frequent mitosis causes abnormal growth which may form a disorganized mass called a tumor. What is a benign tumor? A tumor which remains in place like a lump, but it eventually interferes with function of healthy tissue. What is a malignant tumor? A tumor that is cancerous, invasive, and extends into surrounding tissue. What happens if a malignant tumor is untreated? It will reach the circulatory/lymphatic system and spread or metatasize. What is cancer? A collection of disorders categorized by their origin and affected cell type. What are five things used to treat cancer? Surgery, radiation, chemotherapy, medication (immune therapy), and bioengineering What is bioengineering? It blocks signals that causes cancer cells to divide. What are four reasons cancer is thought to occur? Genetics, exposure to radiation/chemicals, failure of normal programmed death of cells, and inability of immune systems to identify and destroy cancer cells What are oncogenes? Genes that activate genes that increase cell division. How are tumor suppressor genes linked to cancer? When tumor suppressor genes are inactivated or removed, cell reproduction is not controlled What are stem cells? Stem cells are cells that can form two daughter cells like itself or one partially specialized cell and one unspecialized cell Why are stem cells so important in cancer research and other kinds of research? Stem cells can become any kind of cell, so they could be used to control cancerous tumors and growths, undo paralysis, and many other things. What is a progenitor cell? A partially specialized cell. It has a limit of what kind of cell it can become. What is a totipotent cell? It can give rise to every cell type (stem cells). What is a pluripotent cell? It has daughter cells that can become ONE of a variety of different cells of the same type (progenitor). What is the definition of metabolism? The sum total of all chemical reactions that occur within the cell. What are two major types of metabolic processes? Anabolic Metabolism (Anabolism) and Catabolic Metabolism (Catabolism) What is the most characteristic thing about anabolism? It requires energy. What are some facts about anabolism? It's constructive, it is necessary in simple growth and cell repair, and it is accomplished by dehydration synthesis. What is the most characteristic thing about catabolism? It gives off energy. What are some facts about catabolism? It is destructive, it is meant to break down substances into a form that the body can use, and it is accomplished by hydrolysis. Both catabolic and anabolic reactions are controlled by ____. Enzymes What are some features of enzymes? Protein catalysts, specific to a substrate, and can be reused because they are not altered during the reaction. What do enzymes do when they are working as protein catalysts? They speed up reactions by lowering activation energy. What is activation energy? The energy required for a reaction to occur. The basic knowledge and definitions needed in order to master the upper level of cells and the processes in cell metabolism