Unit 3 Test Review Flashcards
what is a substrate?
substance(s) / reactant(s) and enzyme works on
what is an active site?
the location where the substrate binds to an enzyme
what is an enzyme-substrate complex?
a combination of enzyme and substrate. they are connected by weak bonds (usually ionic or hydrogen bonds) that trigger shape changes in the enzyme and as the enzyme changes shape, more weak bonds form to allow the two to fit even more closely together
what is induced fit?
the tightening of binding after original contact
different enzymes link to different molecules based on their ____ and ____
aa composition and tertiary structure
for an enzyme-mediated chemical reaction to occur, the ____ and ____ must be compatible with the active site of the enzyme
the shape and charge
the structure and function of enzymes contribute to the ____
regulation of biological processes
enzymes are biological catalysts that facilitate ____ in cells by lowering the ____
chemical reactions and activation energy
what is a catalyst?
a chemical agent that speeds up a reaction without being used up by the reaction
most cellular catalysts are ____ but some RNA molecules called ____ can also act as cellular catalysts
proteins and ribozymes
all chemical reactions involve ____
the breaking and reforming of bonds
converting molecules from one format to another usually involves ____
altering the starting molecule to an unstable form before the reaction
reactants require ____ to get to an unstable state
energy
____ is released when new bonds of product form
heat energy
what is activation energy?
an energy investment to start a reaction
once enough activation energy has been absorbed, molecules reach the ____ when the reaction will occur
transition state
what is catalysis?
when enzymes lower the activation energy for a specific reaction
- describe how enzymes catalyze reactions
as the substrate is held in place, r-groups of the aa in the active site aid in the conversion of the substrate from reactant to product. the product enters and is converted and released quickly (typically 1,000 substrate molecules converted per second by a single enzyme).
describe the ways enzymes lower activation energy
moving two substrates into prime orientation for bonding, pulling/distorting a single molecule to aid in breaking apart, or providing a microclimate (ex: lower pH to aid the transfer of h+ ions to the substrate without lowering the overall cell pH)
increasing the concentration of a substrate can increase the ____
rate of a reaction
more substrate ____ odds of collision of substrate and enzyme
increases
once substrate concentration is large enough that all enzymes active sites are engaged with substrate, the enzyme is said to be ____
saturated
change to the molecular structure of a component in an enzymatic system may result in ____
a change in the function or efficiency of the system
denaturation of an enzyme occurs when ____
the protein structure is disrupted, eliminating the ability to catalyze rections
environmental temperatures and pH outside the optimal range for a given enzyme will ____, altering the efficiency with which it catalyzes reactions
cause changes to its structure
temperature and pH can change ____
an enzyme’s shape
temperature can ____ speed of molecules, ____ collisions and providing activation energy
increase and increasing
pH can change enzyme conformation by ____
interacting with Ionic bonds
