Biology Ch. 4

  1. Entropy
    • The tendency towwards randomness
    • the more disordered the system, the higher the entropy
  2. Energy
    the ability ot do work, to move matter
  3. Potential energy
    • Stored energy available to do work
    • A baseball player about to throw a ball
  4. Kinetic energy
    • energy being used to do work
    • Any mkoving object possesses this
    • The soaring baseball
  5. Calorie
    the amount of energy required to raise the temp. of 1 gram of water from 14.5 degrees C to 15.5 degrees C
  6. Kilocalorie
    • The most common unit for measuring the nergy content of food and the heat output of organisms
    • The energy required to raise the temp. of a kilogram of water by 1 degree C
    • 1 kilocalorie=1000 calories
  7. Thermodynamics
    • The syudt of energy transformations
    • The laws regulate the energy conversions vital for life, as well as those that occur in the nonliving world
    • They apply to all energy transformations
  8. First law of thermodynamics
    • The law of energy conversion
    • Energy cannot be created or destroyed but only converted into other forms
    • The total amount of energy is constant
  9. Second law of thermodynamics
    • all energy transformations are inefficient because every reaction loses some energy to the surroundings as heat.
    • You will always lose some energy as heat with every chemical reaction
    • Also says that organisms can increase in complexity as long as something else decreases in complexity by a greater amount
  10. Metabolism
    • The biochemical reactions of a cell
    • Includes all of the chemical reactions in cells, including those that build new molecules and those that break down existing ones
  11. Metabolic pathways
    • When the product of one reaction becomes the starting point, or substrate, of another
    • Enzymes enable metabolic reactions to procedd fast enough to sustain life
  12. endergonic reaction
    • 1 type of metabolic reaction
    • Requires an input of energy to proceed
    • the products contain more energy that the reactants
    • Tend to build complex molecules from simpler components
    • Example- a disaccharide having more energy than its individual monosaccharides-->the reactants must have absorbed energy from its surroundings
  13. Exergonic reaction
    • 1 type of metabolic reaction
    • Releases energy
    • The products contain less energy than the reactants
    • Example-cellular respiration-the breakdown of glucose to carbon dioxide and water
  14. Chemical equilibrium
    • the reaction goes in both directions at the same rate
    • Does not always mean that amounts are equal
    • The rate of formation is equal
  15. Oxidation-reduction (redox) reactions
    • Energy transformation- transfer energized electrons from one molecule to another
    • Oxidation and reductions occur simultaneously b/c if one molecule is reduced (gains electrons), then another must be oxidized (loses electrons)
  16. Oxidation
    • the LOSS of electrons from a molecule, atom, or ion.
    • Adding oxygen because that is strongly electronegative, which attracts electrons away from their original atom
    • release energy as they degrade complex molecules into simpler products
  17. Reduction
    • the GAIN of electrons
    • require a net input of energy
  18. Electron transport chains
    • When groups of cytochromes align in membranes with other proteins, they form these
    • each protein accepts an electron from the molecule before it and passing an electron to the next
    • Small amounts of energy are released at each step of an electron transport chain, and the cell uses this energy in other reactions
  19. ATP
    • AKA adenosine triphosphate
    • Temporarily stores much of the released energy of life
    • A go-between molecule that holds the energy released in exergonic reactions, and then applies it to the endergonic ones
    • Structurally similiar to a nucleotide
    • All cells depend on ATP to power metabolism and many other cellular activities
  20. Coupled reactions
    simultaneous reactions in which one provides the energy that drives the other
  21. Phosphoroylating
    • How a cell uses ATP as an energy source
    • The transfer of its phosphate group to another molecule
    • Can energize the target molecule, making it more likely to bond w/ other molecules-->ATP fuels endergonic reactions
    • Can also change in the shape of the target molecule
    • Uses these changes to move substances throughout the cell
  22. Enzyme
    • A protein that catalyzes (speeds) a chemical reaction without being consumed
    • Usually either dismantle or build other molecules
    • copy DNA, build proteinsdigest food, and recycle a cell's worn out parts
    • Work faster as the temp increases, but only to a limit
    • Drugs and poisons can inhibit function
  23. Energy of activation
    • The amount of energy required to start a reaction
    • Initial energy kick
    • By reducing the energy activation, some enzymes increase reaction rates a billion times
  24. The enzyme's active site
    • the region to which the reactants (substrates) bind
    • The active site does not fit like a key in lock, but contorts slightly
  25. Cofactors
    • Nonprotein helpers
    • Substances that must be present (with also water and substrates) for an enzyme to catalyze a chemical reaction
    • Usually oxidized or reduced during the reaction
    • Not consumed-->return to their original state when the reaction is complete
    • Coenzymes=organic cofactors
  26. Negative feedback
    • An excess of a reaction's product inhibits the enzyme that controls its formation
    • When the product level falls, the pathway resumes its activity
    • A thermostat shuts AC off when it's too cold
  27. Noncompetitive inhibition
    • When product molecules bind to the enzyme at a site other than the active site, but in a way that alters the shape of the enzyme so that it can no longer bind substrate
    • Does not compete to occupy the active site
  28. Competitive inhibition
    • The product of the reaction binds to the enzyme's active site, preventing it from binding substrate
    • The product competes with the substrate to occupy the active site
  29. Positive feedback
    • When a product activates the pathway leading to its own production
    • Example- blood clotting
  30. Concentration gradient
    • A solute is more concentrated in one region than in a neighboring region
    • Tea bag- water is darker around the tea bag
  31. Passive transport
    • When a substance moves across a membrane without the direct expenditure of cellular energy
    • Involves diffusion
  32. Diffusion
    • the spontaneous movement of a substance from a region where it is more concentrated to a region where it is less concentrated.
    • Does not require energy input
  33. Simple diffusion
    • a form of passive transport in which a solute moves dowm its concentratiobn gradient w/o the use of a carrier molecule
    • Ex- lipids, O2, CO2,
  34. osmosis
    the simplle diffusion of water across a biological membrane
  35. Isotonic
    • The plasma's solute concentration is the same as the inside of the red clood cell
    • Water doesn't flow in or out of the cell
    • Has normal doughnut-shaped form
  36. Hypotonic
    • concentration of solutes is lower than inside the cell
    • Water will enter a red blood cell immersed in pure water
    • The cell may burst
  37. Hypertonic
    • higher concentration of solutes than the cell's cytoplasm
    • Cell shrivels and may die for lack of water
  38. Turgor pressure
    • The resulting force of water against the cell wall
    • Wilted flower demonstrate lost turgor pressure
  39. Facilitated diffusion
    • A form of passive transport in which a membrane protein assists the movement of a polar solute along its concentration gradient
    • Does not require energy expenditure
    • Ex- glucose moves into red blood cells through this process
  40. Active transport
    • A cell uses a transport protein to move a solute against its concentration gradient- from where it is less concentrated to where it is more
    • energy to drive this process comes from ATP
  41. Sodium-Potassium pump
    Uses ATP as an energy souce to expel 3 sodium ions for every 2 potassium ions it admits
  42. Endocytosis
    Allows a cell to engulf fluids and large molecules and bring them into the cell
  43. Phagocytosis
    The cell captures and engulfs large particles, such as debris or even another cell
  44. Exocytosis
    • Opposite of endocytosis
    • Uses vesicles to transport fluids and large particles out of cells
Card Set
Biology Ch. 4
Chapter 4