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15 Cards in this Set

  • Front
  • Back
exergonic reaction
A chemical reaction that releases energy
endergonic reaction
A chemical reaction that requires a net input of energy.
energy coupling
the use of energy released from exergonic reactions to fuel essential endergonic reactions
What greatly contributes to the potential energy stored in ATP?
The mutual repulsion of the three negatively-charged phosphate groups in an ATP molecule.
The transferring of a phosphate group from ATP to some other molecule. (ATP --> ADT + P)
What are the three types of cellular work? How does ATP drive each type?
1) Chemical work -- the phosphorylation of of reactant molecules drives the synthesis of of product molecules
2) Mechanical work -- the transfer of phosphate groups to special motor proteins in muscle cells causes the proteins to change shape.
3) Transport work -- active transport (see 5.18)
Why can work be sustained?
ATP is a renewable resource that cells regenerate.
Explain how ATP transfers energy from exergonic to endergonic processes in the cell (explain the ATP cycle).
By phosphorlylation: Exergonic processes phosphorylate ADP to form ATP. ATP transfers energy to endergonic processes by phosphorylating other molecules.
How do enzymes's speed up the cell's chemical reactions?
By lowering energy barriers.
A specific reactant than an enzyme acts on.
active site
the region of an enzyme into which a substrate fits
induced fit
when a substrate binds to an enzyme, the active site changes shape slightly so that it embraces the subtrate more snugly.
Describe the catalytic cycle of an enzyme (use sucrase as example).
1) Sucrase starts with an empty active site
2) Sucrose enters the active site, attaching by weak bonds. An induced fit distorts the sucrose molecule.
3) The weakened bond reacts with water, and the substrate is hydrolyzed to the PRODUCTS glucose and fructose
4) The enzyme releases the products and emerges unchanged from the reaction
a nonprotein helper without which an enzyme will not function
a cofactor that is an organic molecule