MTC Week 5 Flashcards
what are the first 2 laws of thermodynamics
- Energy cannot be created or destroyed
- Universe tends towards disorder (entropy)
what is enthalpy
heat content of a system (lost/ gained in reactions)
what is ΔG?
change in free energy
to have a -△G, △H must be pos or neg
negative because energy is released (exergonic)
to have a +△G, △H must be pos or neg
positive because energy is gained (endergonic)
when will a reaction spontaneously go forwards?
all -△G reactions
+△G reaction if increase susbstrate and and/or decrease product
what is catabolism
break down of complex molecules (polymers) into simpler molecules (monomers)
exergonic
-△G
what is anabolism
synthesising complex molecules (polymers) from simpler molecules (monomers)
endergonic
+△G
what is an exergonic reaction
a reaction that releases energy (to go to state of less disorder)
-△G
catabolism: bonds are being broken down
what is an endergonic reaction
a reaction that requires energy (to go to a state of more disorder)
+△G
Anabolism: bonds being made
what is metabolism
sum total of all chemical reactions in an organism,
catabolic + anabolic = metabolism
how does ATP act in an exergonic reaction
ADP + P to become ATP
how does ATP act in an endergonic reaction
ATP becomes ADP + P
what are the 2 classes of coenzymes
activation-transfer: participates in catalysis by binding with substrate for enzyme to function
oxidation-reduction: does not form covalent bond with substrate
what are coenzymes
energy carriers
what are the most common coenzymes
NADH, NADPH, FADH
What kind of reaction is NADH associated with, what is it oxidized to and what is its ratio in relation to its oxidized state?
catabolic reaction
Oxidized to NAD+
Ratio of NAD+ is kept high in comparison to NADH because it acts as an oxidising agent in catabolic reactions
What kind of reaction is NADPH associated with, what is it oxidized to and what is its ratio in relation to its oxidized state?
anabolic reaction
oxidized to NADP+
Ratio of NADP+ is kept low because it acts as a reducing agent in anabolic reactions
what is FADH oxidized to
FAD+
what are the steps of an enzyme- substrate reaction
- Binding of substrate
E+S <–> ES - Conversion of bond
substrate to bond product
ES <–> EP - Release of product
EP <–> E+P
how does temperature and ph alter enzyme function
increased temperature, denatures enzyme, which changes shape and decreases activity
enzymes are only active in a certain pH range
what are the 3 types of enzymes
isoenzymes
apoenzyme
holoenzyme
what are isoenzymes
enzymes that differ in primary structure but catalyse same reaction
what is an apoenzyme
an inactive enzyme
what is a holoenzyme
formed from an apoenzyme and coenzyme
biologically active enzyme
what does oxidoreductase (dehydrogenase) do
(class of enzyme)
catalyse reactions in which there are electron and/or hydrogen transfers
what does transferase
(class of enzyme)
transfer functional groups from 1 molecule to another
what does hydrolase do
(class of enzyme)
break bonds using water
what does lyase do
(class of enzyme)
break bonds without using hydrolysis or oxidation
what does isomerase do
(class of enzyme)
convert a molecule from 1 isomer to another
what does ligase do
(class of enzyme)
join 2 molecules together via the formation of a new bond
what does the Michaelis-Menten graph show
shows the relationship between substrate and reaction rate
what does Vmax and Km represent on the Michaelis-Menten graph
Vmax = reaction rate when the enzyme is fully saturated
Km = substrate when the reaction rate is 50% Vmax
when Vmax increases what happens to the slope
slope decreases
stimulation lowers
when Vmax decreases what happens to the slope
slop increases
inhibition raises
what is Km dependent on
number of enzymes/receptors
what are the 3 types of enzyme inhibitors
competitive, uncompetitive and noncompetitive
what is the action of a competitive enzyme inhibitor
- competes with substrate binding at the active site
- increase Km
- Vmax no change
- Overcome with increase substrate
what is the action of an uncompetitive enzyme inhibitor
binds to the enzyme-substrate complex, preventing release of products
what is the action of a noncompetitive enzyme inhibitor
-binds to enzyme outside of the active site so that substrate binding cannot occur normally
-Km is unchanged
-Vmax is decreased
-Irreversible, cannot be overcome
what are allosteric enzymes
enzymes with multiple active sites
what are allosteric enzymes function
regulate metabolic pathways
how do allosteric enzymes regulate metabolism
feedback inhibition (end-product inhibition)
final product acts as a noncompetitive inhibitor of the 1st enzyme
