Biochemistry Flashcards
do enzymes affect the position of the equilibrium?
no, they speed up the rate at which a reaction reaches equilibrium
what do enzymes do to the activation energy?
enzymes lower the activation energy
enzymes with a cofactor are called
holoenzyme
enzymes without a cofactor
apoenzyme
protein kinases carry out which reaction
phosphorylation reactions
Vmax
maximum rate of reaction at unlimited substrate concentration
Km
50% Vmax
competitive inhibitor
binds to active site, Vmax remains same, Km varies
non-competitive inhibitor
binds to site other than active site, Km remains same, Vmax varies
nucleoside
base and sugar
nucleotide
nucleoside and phosphate group
purines
adenine and guanine
pyrimidines
uracil, cytosine, thymine
eukaryotic cells have three types of polymerases
pol I, pol II, pol III
pol II
synthesises all mRNA
transcription stages
RNA polymerase binding
DNA chain separation
transcription initiation
elongation
termination
translation stages
initiation, elongation, termination
3 tRNA binding sites
exit, peptidyl, aminoacyl
degenerate
many amino acids have more than one codon
unambiguous
each codon codes only for one amino acid
glycolysis
conversion of glucose to pyruvate
what is the net gain of ATP per glucose
4 ATP
which kinase phosphorylates glucose
hexokinase
which kinase phosphorylates fructose-6-phosphate
phosphofructokinase
what does pyruvate kinase do?
converts phosphoenolpyruvate to pyruvate
phosphofructokinase
key enzyme in control of glycolysis
negative modulators
ATP
citrate
H+
positive modulators
AMP
fructose-2
6-biphosphate
NAD in glycolysis
NAD+ reduced to NADH + H+
from each acetyl-coA, TCA cycle generates
3 NADH + H+
1 FADH2
1 GTP
2 CO2
standard redox potential
a measure of how readily a substance donates an electron
negative= reduced form of x has lower affinity for electrons than hydrogen
positive= reduced form of X has higher affinity for electrons than hydrogen
inhibitors of oxidative phosphorylation
cyanide
azide
CO
