ch 8: energy and enzymes Flashcards
1st law of thermodynamics
energy is neither created, nor destroyed
- it can be transferred or transformed
2nd law of thermodynamics
when energy is converted from one form to another, some of that energy becomes unavailable to do work
why do products have less potential energy than the reactants in biochemical reactions?
due to a release of energy during the reaction
what type of energy is released during the hydrolysis of polymers?
chemical energy
what helps drive the movement of ions through channels?
electrical gradients
what can be released by chemical reactions?
heat
what is captured by pigments?
light energy
what is used in muscle movements?
mechanical energy
metabolism
sum of all biochemical reactions in an organism
catabolic reactions
break down molecules
- example: hydrolysis
anabolic reactions
reactions that build molecules
- example: condensation
exergonic
when G is negative —> energy is released
- spontaneous
endergonic
when G is positive –> energy is consumed
- nonspontaneous
example of endergonic reaction
active transport
example of exergonic reaction
diffusion
if a bond is harder to break, why does it have less potential energy?
energy gets used up because it takes more energy to break the bond
do nonpolar bonds have high or low potential energy?
high
do polar bonds have high or low potential energy?
low
redox reactions
oxidation and reduction
oxidation
loss of electron
reduction
gain of electron
what do redox reactions transfer?
electrons alone or along with protons (H+)
when NAD gets reduced, it becomes
NADH
when FAD2+ gets reduced, it becomes
FADH2
what type of reaction is reducing FAD and NAD?
endergonic, non-spontaneous reactions
where does ATP hold energy?
phosphate bonds
coupling reactions
energy released from an exergonic reaction drives an endergonic reaction
what has to happen for FAD and NAD to be reduced?
the reaction has to be coupled with another one
what happens when ATP is hydrolyzed?
energy is released
is ATP hydrolysis a redox reaction?
no, it is a catabolic reaction because it involves breaking down a molecule not transferring electrons/protons
what is the endergonic reaction of the ATP cycle?
a phosphate group gets added to ADP to create ATP and energy is added (ATP synthesis)
what is the exergonic reaction of the ATP cycle?
phosphate is removed from ATP to create ADP and energy is released (ATP hydrolysis)
exergonic reactions ____ energy
release
endergonic reactions ____ energy
require
what is ATP hydrolysis coupled to?
endergonic reactions
what links endergonic and exergonic pathways?
ATP hydrolysis + condensation
what do enzymes contain to help biochemical reactions?
binding sites for coupled reactions
do enzymes reduce or increase the activation energy?
reduce because it facilitates the reaction between the molecules
do enzymes increase or decrease reaction rate?
increase
allosteric regulation: inhibition
binding of regulatory subunit to enzyme, changes the shape of the enzymes so substrate can’t bind at active site of enzyme
competitive inhibition
a molecule similar to the substrate binds to the enzyme and blocks substrate bonding
allosteric regulation: activation
binding of regulatory subunit of enzyme, changes the shape of the enzymes and now substrates can bind to the active site of the enzyme
what is a type of allosteric activation?
adding a phosphate
what can influence enzyme functions?
cofactors such as coenzymes and ATP
