Bio Exam 2

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Bio Exam 2
2011-10-12 18:06:48
Bio Biology San Antonio College SAC

CHS. 3, 4, 5, & 24 {Text} EXS. 6, 8, & 9 {Lab. Manual
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  1. Explain the basic nature of mitotic cell division.
    The mother cell divides into 2 daughter cells, and the 2 daughter cells receive the same DNA { Chromosomes} as the mother cell. So these 2 cells are genetically identical.
  2. Describe the 2 parts of mitotic cell division:
    • mitosis - division of the nucleus into 2 identical nuclei.
    • cytokinesis – division of the cytoplasm and cytoplasmic organelles into 2 cells.
  3. Interphase
    • Nuclear envelope intact.
    • Nucleoli intact.
    • DNA loosely coiled so occurs as chromatin.
    • DNA replicates during interphase.

    • After DNA replication the 2 replicate DNA molecules are held together by a structure called a centromere. This referred to as a doubled stranded chromosome.
    • The replicate DNA molecules of a doubled chromosome are called chromatids.
    • The structure that attaches the chromatids of a double stranded chromosome is a centromere.
  4. Prophase
    • Major occurrences:
    • Nuclear envelope breaks down.
    • Nucleoli break down.
    • DNA coils, tightens, untangles and becomes visible as distinct structures called chromosomes.
    • Spindle begins to form.
  5. Metaphase
    • Major occurrence:
    • The double stranded chromosomes attach to spindle fibers and become aligned along the equatorial plane of the spindle.
  6. Anaphase
    • Major occurrences:
    • Centromeres split and chromatids separate and single stranded move or migrate toward poles of the spindle.
  7. Telophase
    • Begins with the arrival of the chromosomes at the poles of the spindle.
    • The events are the reverse of prophase:
    • Nuclear envelopes reformed.
    • Nucleoli reformed.
    • DNA becomes loosely coils forming chromatin.
    • Spindle breaks down.
  8. Cytokinesis
    • Occurs by the formation of a cleavage furrow.
    • Most occurs during telophase.
  9. In terms of electrons, explain when a substance is reduced and when it is oxidized.
    A substance is reduced by the addition of electrons, and a substance is oxidized by the removal of electrons.
  10. Explain the 2 main ways a substance can be reduced and oxidized.
    • A substance is reduced by {1} the addition of H’s or {2} the removal of O.
    • A substance is oxidized by {1} the removal of H’s or {2} the addition of O.
  11. In biological systems what is the most frequent mechanism of oxidation- reduction reactions?
    The addition and the removal of H’s.
  12. In the process of cellular respiration, the energy released due to the oxidation of food molecules {glucose } is stored in the form of what compound?
    It is stored in the form of ATP’s.
  13. What is the direct source of energy for most cellular activities?
    • The direct source of energy is through this reaction:
    • ATP -------> ADP + P + Energy
  14. Cell respiration of carbohydrates:
    Aerobically glucose can be broken down in 4 steps. List these steps.
    • Glycolysis
    • Oxidation of pyruvic acid
    • Krebs Cycle
    • Electron transport chain
  15. Glycolysis
    One molecule of glucose is broken down to 2 molecules of what substance?
    Pyruvic acid
  16. Glycolysis
    How many steps {reactions }?
    A sequence of 9 reactions.
  17. Glycolysis
    How many molecules of ATP are consumed for every molecule of glucose?
    2 ATP’s.
  18. Glycolysis
    How many molecules of ATP are synthesized by substrate phosphorylation per molecule of glucose?
    4 ATP’s.
  19. Glycolysis
    What is the net ATP production per glucose molecule?
    2 ATP’s.
  20. Glycolysis
    What are the 2 end products?
    The 2 ATP’s and the 2 NADH 's.
  21. Glycolysis
    In what of the cell does this process occur?
    In the cytoplasm.
  22. With anaerobic conditions what happens to the pyruvic acid resulting from glycolysis?
    It’s reduced by the NADH formed in glycolysis to lactic acid.
  23. With aerobic conditions what happens to the pyruvic acid resulting glycolysis?
    It moves into the mitochondria where it is oxidized; resulting in 2 CO2's being liberated, 2NADH’s being formed, and 2 acetyl coenzyme A’s being formed.
  24. Krebs Cycle:
    • A cyclic sequence of reactions, and with each turn 3 significant things occur:
    • 2 CO2's are liberated.
    • 1 ATP is synthesized.
    • 8 electrons are removed forming 3 NADH’s and 1 FADH2.
  25. Krebs Cycle:
    Explain how the carbons of glucose are liberated as CO2
    • 2 CO2's are liberated with the oxidation of the 2 pyruvic acid molecules.
    • 4 CO2's are liberated with 2 turns of the Krebs cycle.
  26. Krebs Cycle:
    How many molecules of ATP are synthesized by substrate phosphorylation for each turn of the cycle?
    1 ATP
  27. Krebs Cycle:
    What is the net ATP production per glucose molecule?
    2 ATP’s
  28. Krebs Cycle:
    In part of the cell does process occur?
    In the matrix of the mitochondria
  29. Electron Transport Chain
    Describe oxidative phosphorylation?
    • The method of making ATP’s using the electron transport chain.
    • Description:
    • Electrons are passed 2 at a time down a chain of electron acceptor molecules to O2 forming H2O; as the electrons are passed energy is released and ATP’s are synthesized.
  30. Describe chemiosmosis {chemiosmotic phosphorylation}
    • As electrons are passed down the electron transport chain, the energy released drives the hydrogen ion pump that moves hydrogen ions from the mitochondrial matrix into the intermembranous space { between the inner and outer membranes of the mitochondria }.
    • The hydrogen ion concentration is now greater in the outer compartment.
    • This concentration gradient and electrical gradient causes hydrogen ions to move through hydrogen channels { ATP synthase complex } in the inner membrane.
    • Energy associated with the flow of these hydrogen ions through these channels is used to synthesize ATP from ADP and P.
  31. How many electrons are passed along the chain per glucose molecule?
    24 electrons are passed along the chain.
  32. List the 3 sources of these electrons.
    • The 2 NADH’s formed during glycolysis{source of 4 electrons}.
    • The 2 NADH’s formed during the oxidation of the 2 pyruvic acid molecules{source of 4 electrons}
    • The 6 NADH’s and 2 FADH2 ‘s formed with 2 turns of the Krebs cycle{source of 16 electrons}.
  33. How many ATP's are synthesized per glucose molecule?
    32 ATP’s
  34. What is the role of O2?
    It is the final electron acceptor.
  35. In what part of the cell does this process occur?
    In the inner membranes of the mitochondria
  36. What is the net ATP production for the complete respiration of one molecule of glucose?
    36 ATP’s.
  37. How efficient is the process of cellular respiration of glucose?
    It is about 39% efficient. A glucose molecule contains 686 kilocalories, and each ATP contains 7.5 kilocalories. So 36ATP’s contain 270 kilocalories{36X 7.5}, which is 39% of 686.
  38. Cell respiration of fats:
    The fat molecule is broken down by hydrolysis into glycerol and fatty acids, and then the glycerol and fatty acids which then enter the Krebs cycle and the electron transport chain
  39. Explain how glycerol is used to generate ATP’s
    It enters the Krebs cycle after it is converted to PGAL and then to pyruvic acid.
  40. What is the APT harvest for the complete respiration of glycerol?
    Since glycerol is half a glucose molecule the energy harvest would half of that for glucose - 18 ATP’s per glycerol molecule.
  41. Explain how fatty acids are used to generate ATP’s:
    • The fatty acids are broken down into 2 C fragments {acetyl groups} by a sequence of reactions called beta oxidation.This process occurs in the mitochondria, so the acetyl groups enter the Krebscycle immediately.
    • Description of beta oxidation:The fatty acids are first activated by a coupled reaction with ATP and combined with coenzyme A.
    • After being oxidized twice, forming NADH and FADH2, acetyl Co-A is cleaved off and the process begins again until all of the C’s of the fatty acid are cleaved off in 2 C fragments as acetyl Co-A.
    • The acetyl Co-A’s then enter the Krebs cycle.
  42. What is the ATP yield for the beta oxidation of a fatty acid?
    • For each 2 carbon fragment {acetyl Co-A} removed from the fatty acid, the cell gains 12 ATP’s from the acetyl Co-A’s entering the Krebs cycle plus 5 ATP’s from the NADH and FADH2 which were formed by twice oxidizing the fatty acid before cleaving the acetyl Co-a.
    • Electrons from these NADH and FADH2 are feed directly into the electron transport chain.
    • Form an 18 C fatty acid the cell gains a net 144 ATP’s.
    • This is about1.3 times greater than the ATP’s obtained from the cell respiration of 3 glucose molecules.
  43. Cell respiration of proteins:
    When are proteins used to generate ATP’s?
    • When more protein is ingested than is needed to replace tissue protein, the amino acids are oxidized for energy or converted to fat.
    • In other energy sources {carbohydrates and fats} are inadequate, the mitochondria can break down these surplus amino acids in the Krebs cycle and electron transport chain to generate ATP’s.
  44. Explain how amino acids are used to generate ATP’s.
    • Before amino acids can be oxidized to generate ATP’s, they must be deaminated.
    • In this process the amino group is removed and picks up a H to form NH3.
    • The NH3 combines with CO2 to form urea - most of which is secreted in the urine.
    • The resulting molecule is converted to a Keto acid which can then be converted to pyruvic acid, acetyl C0-A, or one of the keto acids of the Krebscycle.
    • In this way ATP’s are generated by the Krebs cycle and the electron transport chain.
  45. What is the ATP harvest for the respiration of an amino acid?
    Since not all amino acids enter the Krebs cycle at the same point, the ATP yield varies. However the average ATP yield per gram is comparable to that of carbohydrate respiration.
  46. 3 factors that make the respiration of proteins an impractical source of quick energy.
    • Proteins are more difficult to break apart than complex carbohydrates and fats.
    • One of the by products of protein respiration, NH3, is a toxin that can damage cells.
    • Proteins form the most important structural and functional components of the cell. So extensive protein respiration threatens homeostasis at the cellular and system levels.
  47. List the 4 types of animal tissues.
    connective, muscle, nervous, and epithelial
  48. Know the following about epithelial tissues:
    Found lining the body {skin}, lining cavities and tubes of the body,and form some glands.
  49. Know the following about epithelial tissues:
    • These functions include{1} protection, {2} absorption, {3} secretion, {4} diffusion, {5} filtration, and {6} movement of materials at their surface.
    • To perform their functions epithelial tissues exhibit certain features.
    • For example epithelial tissues whose function is protection have several layers of cells; whereas epithelial tissues whose function is diffusion or filtration has 1 layer of cells.
  50. Characteristics of Epithelial Tissues
    • 1.Cellularity: Epithelial tissues are composed of large numbers of cells with little matrix. They are primarily cellular tissues.
    • 2.Cell Junctions: The epithelial cells are held together by desmosomes and tight junctions.
    • 3.Organization: Cells organized into sheets.Epithelial tissues have 2 surfaces:
    • a.Free surface - this surface is not attached; it interacts with the external environment - it is uncovered.
    • b.Basement membrane - it attaches the tissue to the underlying connective tissue. It is noncellular and consists of extracellular material produced by both the epithelial cells and the cells of the underlying connective tissue.
    • 4.Avascular: Epithelial tissues have no blood vessels so no blood in this tissue.Their cells depend upon the blood supply in the underlying connective tissue.
    • 5.Regeneration: Most epithelial cells are replaced when they are sloughed off or die.
  51. Classification of epithelial tissues:
    • Epithelial tissues are classified according to 3 criteria:
    • Structure
    • Location
    • Organization into glands
  52. Classification of epithelial tissues according to structure:
    • 1. The shape of the cells at the free surface:According to shape of their cells, epithelial tissues can be:
    • a.Squamous - flat, thin cells
    • b.Cuboidal - cells are about the same height and width - cube shaped.
    • c.Columnar - cells are taller than they are wide - column shaped
    • 2.The number of layers of cells:
    • According to number of layers of cells, epithelial tissues can be:
    • a.Simple - 1 layer of cells
    • b.Stratified - 2 or more layers of cells.
  53. According to location epithelial are classified as:
    • 1.Endothelium: Consist of a single sheet of simple squamous epithelium with its basement membrane.It lines the cardiovascular system and the lymphatic vessels, where it provides a smooth friction-reducing surface for the flow of blood and lymph.
    • 2.Epithelial membranes: They consist of a sheet of epithelial tissue and an associated layer of connective tissue. According to location there are 3 types of epithelial membranes:
    • a.Mucous membranes:Membranes that line the organ systems that open to the outside.These include the respiratory, digestive, urinary, and reproductive tracts.
    • b.Serous membranes:Membranes that line the body cavities that do not open to the exterior.These include the pleura{ which lines the thoracic cavity}, the pericardium {which lines the pericardial cavity}, and the peritoneum {which lines the abdomino-pelvic cavity}.
    • c.Cutaneous membranes:The membrane that lines the body, the skin.
  54. Classification of epithelial tissue according to organization into glands:
    Glands are or 1 or more cells that produce and secrete a product called a secretion.
    According to where their secretion is released glands can be classified as:
    • 1.Exocrine glands - release their secretion into ducts that open to a surface. Examples include salivary glands, sebaceous glands, and sweat glands.
    • 2. Endocrine glands - release their secretion into the surrounding interstitial fluid - in many cases the blood. The secretion of endocrine glands are hormones. Examples include the thyroid gland, pituitary gland, adrenal glands, and pancreas.
  55. Classification of epithelial tissue according to organization into glands:
    According to their method of secretion glands can be classified as:
    • 1.Merocrine glands - cells release their secretory products by exocytosis. Examples are sweat glands, salivary glands, and the pancreas.
    • 2.Apocrine glands - secretory products are released by the shedding of apical portions of cells. The apex of the cell pinches off releasing the secretion and a small amount of cytoplasm. Examples include apocrine sweat glands and mammary glands.
    • 3.Holocrine glands - the cells undergo growth and production of large amounts of secretory products. The secretory products are released when the cell dies. Example - sebaceous glands.
  56. Connective tissue main difference from epithelial tissue.
    Characterized by few cells scattered among large amounts of matrix. The matrix predominates
  57. Connective tissue located.
    Most widely distributed tissue of the body. Examples include abundant loose connective tissue{ areolar and adipose} located in and around other tissues,tendons, ligaments, cartilage, bone, and blood.
  58. 2 Components of connective tissues:
    Matrix and Cells
  59. Matrix
    It’s the nonliving extracellular material
  60. 2 parts of matrix
    Ground substance and Connective fibers
  61. Ground substance
    Homogenous substance consisting mainly of a complex mixture of proteins. It occupies the area around the cells and fibers. It’s of cellular origin - that is it is produced by the cells of the connective tissue.
  62. Connective fibers
    Proteinaceous threads embedded in the ground substance
  63. 3 types of connective tissue fibers
    • Collagen fibers {White fibers}
    • Elastic fibers {Yellow fibers}
    • Reticular fibers
  64. Collagen fibers {White fibers}
    • Most abundant of the fibers.
    • Composed of protein molecules called collagen.
    • These molecules are assembled into cross-linked fibrils.
    • These fibrils are bundled into the thick collagen fibers.
    • These fibers are very tough and have great tensile strength, but are not elastic.
    • They function to provide a structural framework and to provide strength to the tissue.
  65. Elastic fibers {Yellow fibers}
    • Composed of protein molecules called elastin.
    • These molecules form long thin fibers that form branching networks in the matrix.
    • These fibers are very elastic.
    • They function in allowing tissues to stretch and recoil.
  66. Reticular fibers
    • They are immature collagenous fibers so composed of collagen molecules.
    • These molecules form short fine fibers which branch to form delicate networks in the matrix.
    • They are abundant in connective tissues that abut other tissue types, for example in the basement membrane of epithelial and around capillaries.
  67. Mesenchymal cells
    Primitive or embryonic cells that give rise to all the other connective tissue cells.
  68. Fibroblasts
    Flat, branching cells and are the main cells in connective tissue proper.
  69. Adipose or fat cells
    Develop from fibroblasts - store large quantities of fats in their cytoplasm - among the largest cells in the body.
  70. Macrophages
    Phagocytic cells of connective tissues
  71. Mast cells
    Usually clusters around blood vessels - initiate local inflammatory responses by releasing heparin and histamines.
  72. Chondrocytes
    Main connective tissue cells of cartilage.
  73. Osteocytes
    Main connective tissue cells of bone
  74. Blood cells
    Connective cells of blood.