biochemistry Flashcards
name 2 polysaccharides
cellulose and glycogen
free energy chain equation
ΔG = ΔH – TΔS
exergonic reaction
total free energy of products < reactants
ΔG in exergonic reaction
negative
what reactions can occur spontaneously
exergonic
what is the net gain of ATP in glycolysis
2
how many ATP molecules are generated in glycolysis
4
what is Gluconeogenesis
Making new glucose from non-carbohydrate precursors, e.g. pyruvate
what reactions are used as control points
with large negative ΔG values
given an example of a catabolic pathway
glycolysis
give an example of an anabolic pathway
gluconeogenesis
what is stronger -H or covalent bonds
covalent
which amino acids is neither in D or L configuration
glycine
what are D and L forms
stereoisomers
describe peptide bonds
planar
partial double bond character
what does the HH equation do
calculate the properties of a buffer solution
what are zwitterions
amino acids without charged side groups
what is isoelectric pH
the pH at which a molecule has no net charge
given an example of a protein acting as a buffer
Hb in blood
what angles can the polypeptides rotate around
a carbon and amino group
a carbon and carboxyl group
what side is the a helix handed
right
what do proline residues do to a helix
break them
what are the turns between β sheets strands
glycine and proline
what protein has different 2y structure elements
phosphoglycerate kinase
what is tropocollagen
the molecular component of collagen
what does tropocollagen consist of
3 polypeptide chains coiled around eachother
what does covalent crosslinking in collagen do with age
inc
what does scurvy result in
weakened collagen - bleeding gums
fibrous proteins
contain polypeptide chains organised parallel long a single axis
fibrous protein exampple
keratin and collagen
globular proteins
spherical shape
globular proteins exmaples
myoglobin and Hb
name some forces stabilising 3y structures
Covalent disulphide bonds Electrostatic interactions = salt bridges Hydrophobic interactions Hydrogen bonds Complex formation with metal ions
what does sickle cell anaemia result from
a change from glutamic acid to valine
what does sickle cell anaemia result in
rigid sickle shape cells - can block blood flow in capillaries
what results from incorrect protein folding
alzheimers, parkinsons, CJD
what is mad cow disease caused by
infection
what is CJD caused by
spontaneous or inherited mutation
what is CJD caused by
prion proteins
where are new nucleotides only added
to a free 3’ end
how many bonds between A and T
2
how many bonds between C and G
3
what is dna replication catalysed by
dna polymerase
what are the properties of DNA polymerase
can only add to existing nucleic acids
can not start DNA synthesis on their own
require an RNA primer to start replication
how is the lagging strand replicated
Okazaki fragments
what unwinds teh DNA
helicase
what is the RNA primer for DNA polymerase synthesized by
primase
what is the proofreading system that DNA polymerase has
3’ to 5’ exonuclease activity that removes incorrect nucleotides
what does RNA contain
stem loops
what does tRNA have
an anticodon
what is the bonds that hold together primary protein structure
peptide (covalent)
what does a-amanitin do to RNA polymerase II
inhibits it
which type of RNA polymerase synthesises all mRNA
Pol II
how does transcription begin
binding of TFIID to TATA box
what does TFIID
introduce kink into DNA and provide a landing platform fro further transciption factors and RNA polymerase
does RNA polymerase require a primer
no
what is the new RNA sequence to the template strand
complementary
what is the new RNA to the coding strand
identical
how are steroids transported in blood
bound to albumin or other proteins
what is added to the end of mRNAs
poly A tail and 5’cap
how are free ribosomes translocated
post translationally
how are bound ribosomes in RER translocated
co translationally
how do enzymes reduce the activation energy
provide alternative pathways
what is an apoenzyme
enzyme without a cofacotr
what is a holoenzyme
enzyme with a cofactor
what are tightly bound coenzymes called
prosthetic groups
what are metalloproteins
Metal cofactors form a metal co-ordination centre in the enzyme
what do vitamins function as
coenzymes
what are isozymes
isoforms of enzymes that catalyse the same reaction but have different properties and structure
what does lactate dehydrogasne do in the heart and muscle
H (Heart) – promotes aerobic metabolism
M (Muscle) promotes anaerobic metabolism
what enzyme carries out phosphorylation reactions
kinases
what are zymogens
inactive precursors of enzyme
what is Km
half V max
what is the intersection with x axis in Lineweaver-Burk plot
Km
what is the intersection with y axis in Lineweaver-Burk plot
Vmax
what has a higher affinity for glucose - hexokinase or glucokinase
hexokinase - lower Km
what does a low Km suggest
high affinity of enzyme for its substrate
do allosteric enzymes follow MM kinetics
no - sigmoidal curve
where is GLUT3 found
brain
where is GLUT1 found
brain
what is glycolysis
conversion of glucose to pyruvate
name 3 control points in glycolysis
hexokinase
Phosphofructokinase
pyruvate kinase
what does hexokianse control
substrate entry
what does Phosphofructokinase control
rate of flow
what does pyruvate kinase control
product exit
how is Phosphofructokinase controlled
energy change
what is used to ferment pyruvate to lactic acid
NADH
what is the Warburg effect
upregulation of anaerobic glycolysis in cancer cells - produce energy
what must happen to NADH for glycolysis to continue
re oxidised - NAD+ is regenerated through the oxidative metabolism of pyruvate
where does the TCA cycle occur
mitochondria
TCA cycle - overall production
3 NADH
FADH2
2 CO2
GTP
what is the enzyme of the TCA cycle that is not located in the mitochondrial matrix
succinate dehydrogenase - inner mitochondrial membrane
what is the yield of one molecule of glucose
4 ATP 10 NADH 10 H 2 FADH2 4 CO2
what does pyruvate dehydrogenase deficiency result in
poor muscle tone
retardation and seizures
resp problems
where are ketone bodies formed
liver
are ketone bodies acid or alkali
strongly acidic
what is diabetic ketoacidosis
Hyperventilation with a severe metabolic acidosis.
what allows NADH from the cytoplasm to cross the inner mitocondrial membrane
malate aspartate shuttle
what does a negative electron transport potential mean
reduced form of X has a lower affinity for electrons than H
which resp complex doesn’t pump H
II
what is ATP synthase also called
F1F0ATPase
which part of ATP synthase protrudes into the mitochondiral matrix
F1