Chapters 5 & 6

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Chapters 5 & 6
2010-12-12 20:54:52
introductory biology

final review
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  1. fluid mosiac model
    phospholipids and proteins that structure the plasma membrane of an animal cell. mosiac describes the surface that is made up of small pieces. it has a diverse collection of protein molecules embedded in the framework of phospholipids

    doule bonds in the unsaturaged fatty acid tailes produce kings that prevent them from packing tightly together- this leaves the membrane fluid so that things can pass through.

    cholesterol wedged into the bilayer helps stabilize the membrane at warm temperatures but also helps keep the membrane fluid at lower temperatures.
  2. diffusion
    is the tendency for particles of any kind to spread out evenly in an available spae, moving from where they are more concentrated to regions where they are less concentrated.

    diffusion requires no work it occurs from the thermal motion of atoms and molecules
  3. facilitated diffusion
    when a protein helps transport a substance down its concentration gradient.

    this is a type of passive transport becuase it does not require energy
  4. concentration gradient
    an increse or decrease in the density of a chemical substance in an area. cells often maintain concentration gradients of ions across their membranes. when a gradient exists, substances tend to move from where they are more concentrated to where they are less concentrated.
  5. active transport
    a cell has to expend energy to move a solute against its concentration gradient. or across the membrane toward the side where the solute is more concentrated.
  6. exocytosis
    export of bulky materials like proteins or polysaccharides . transport vesicles filled with macromolecules bud from the golgi and move to the plasma membrane and then fuse and push the contents out of the cell. the vesicle becomes part of the plasma membrane.
  7. endocytosis
    the opposite of exocytosis. materials are transported into the cell.

    three types of endocytosis- phagocytosis, pinocytosis, recceptor mediated endocytosis
  8. phagocytosis
    a cell "eats" a particle by wrapping around it and packaging it. a lysosome then attaches and digests the contents
  9. hypertonic
    a solution with a higher solute concentration.

    red blood cells shrivel and die from water loss when put in a hypertonic solution
  10. hypotonic
    a solution with a solute concentration lower than that of the cell.

    red blood cells gail water and by swell and burst when put in a hypotonic solution
  11. isotonic
    solution that is the same concentration as the cell. it will maintain volume in this solution.

    blood plasma is isotonic
  12. osmosis
    diffusion of water molecules across a selectively permeable membrane
  13. turgor pressure
    main pressure of the cell contents against the cell wall in plant cells and bacteria cells, determined by the water content of the vacuole, resulting from osmotic pressure
  14. tonicity
    cells shirnk in a hypertonic solution and swell in a hypotonic solution. in isotonic solutions, animal cells are nomal but plan cells are limp. the control of water balance is called osmoregulation.
  15. energy
    the capacity to perform work, work is performed when an object is moved against an opposing force.
  16. First Law of Thermodynamics
    energy in the universe is constant and can not be created or destroyed but only transferred and transformed.
  17. entropy
    measure of disorder or randomness
  18. Second Law of Thermodynamics
    during every energy transfer some energy becomes unusable. normally this is exhibited in the release of heat or random motion of molecules.
  19. energy coupling
    use of energy released from exergonic reactions to drive essential endergonic reactions. crucial ability of all cells. ATP molecules are the key to energy coupling
  20. ATP
    powers nearly all forms of cellular work. adenosine triphosphate has a nitrogenous base, ribose, and a five carbon sugar.
  21. phosphorylation
    transfer of the third phosphate group from ATP to some other molecule. most cellular work depends on ATP energizing molecules by physphorylating them
  22. reactants
    starting material in a chemical reaction
  23. products of a chemical reaction
    ending material in a chemical reaction
  24. enzyme
    proteins that function as biological catalysts increasing th rate of a reaction without being consumed. speeds up a reaction by lowering the EA barrier.
  25. coenzyme
    cofactor- non protein helper tha many enzymes require. some are inorganic like zinc, iron, or copper. if it is an organic molecule it is called a coenzyme- most vitamins are coenzymes
  26. active site
    region of the enzyme where the reactant acts on the substrate. it is typically a pocket or groove on the surface of the enzyme. these are specific to the substrate it needs
  27. substrate
    specific reactant that an enzyme acts on is called a substrate
  28. competitive inhibitor
    reduces an enzymes's productivity by blocking substrates from entering the active site. this can be overcome by increaseing the concentration of the substrate.
  29. noncompetitve inhibitor
    doesn't enter the active site but binds to the enzyme somewhere else and changes it shape so that the active site no longer fits the substrate

    pesticides and drugs do this
  30. feedback inhibition
    metabolic reaction is blocked by the broduct of the cell- the cell produces so much it keeps the enzyme from working. this is an important process that helps the body regulate how much of what it produces.
  31. aerobic respiration (cellular respiration)
    harvesting of energy from sugar by cells. yeilds carbon dioxide, water, and large amounts of ATP
  32. coenzyme NAD+
    works with dehydrogenase to oxidize glucose. is an organic molecule tha cells make from the vitamin niacin and then use to shuttle electrons in redox reactions
  33. NADH
    NAD+ picks up two electrons (one reduces the + charge) and becomes reduced to NADH. one proton is released in this interaction.
  34. glycolysis
    occurs in the cytoplasmic fluid of the cell outside the organelles. begins respiration by breaking glucose into two molecules of three carbon compound called pyruvate
  35. intermediates
    one of the compounds that form between the initial reactant and the final product in a metabolic pathway, such as between glucose and pyruvate in glycolysis
  36. pyruvate
    gets built onto during the time it is in the mitochondrion. a carboxyl is taken away as CO2, the two carbon compound that remains is oxidized and an NAD+ is made into NADH. a compound called coenzyme A (derived from vitabin B) joins to make acetyl CoA which goes into the citric acid cycle. for each glucose that goes into glycolysis, two acetyl CoA are produced from pyruvate
  37. ATP synthases
    protein complexes built into the inner membrane that synthesize ATP.
  38. Acetyl CoA
    high energy molecule that goes into the citric acid cycle
  39. Krebs Cycle (citric acid cycle)
    enzymes process pyruvate releasing CO2 and producing NADH and acethl CoA. then the cycle starts with a two carbon acetyl group being added to a four carbon compound, forming citrate, which is degraded back to the starting four carbon compound. for each turn of the cycle. 2 CO2 are released.

    the energy yeild is 1 ATP, 3 NADH, 1FADH2
  40. FAD, FADH2
    flavin adenine dinucleotide (FAD) is a redox cofactor involved in several important reactions in metabolism. FAD can exist in two different redox states, which it converts between by accepting or donating electrons.

    FAD can be reduced to FADH2, whereby it accepts two hydrogen atoms (a net gain of two electrons)
  41. oxidative phosphorylation
    involves the electron transport chain and process known as chemiosmosis. NADH and a related electron carrier, FADH2 shuttle electrons to the electron transport chain embedded in the inner mitochondrion membrane. most of the ATP produced by cellular respiration is created by oxidative phosphoryilation which uses the energy released by the downhill fall of electrons from NADH and FADH2 to O2 to phosphorylate ADP
  42. electron transport chain
    a series of electron carrier molecules that shuttle electrons during the redox reactions that release energy used to make ATP. located in the inner membrane of the mitochondria, the thylakoid membranes of chloroplasts and the plasma membranes of prokaryotes.
  43. chemiosmosis
    energy coupling mechanics that uses the energy of hydrogen ion gradients across membranes to phosphorylate ADP, powers most ATP synthesis in cells
  44. lactic acid fermentation
    under anerobic conditions, muscle cells, yeasts, and certain bacteria produce small amounts of ATP by glycolysis. NAD+ is recycled from NADH as byruvateis converted to lactate or alcohol and CO2
  45. what percentage of fuel vs. ATP is actually produced from energy transfer?
    • only 25% of fuel becomes energy
    • 40% in cellular respiration
  46. what is the final electron acceptor in the electron transport system?