Chapter 21: Amino Acid Metabolsim Flashcards
How does nutritional deprevation affect rate of protein degradation?
it increases the rate of protein degradation as proteins are broken down for fuel
What proteins are in lysosomes that allow them to break down proteins?
cathespins
What kinds of muscles do lysosomes break down in order to release proteins during periods of starvation?
muscles that atrophy: like liver and kidneys, but not the ones that don’t atrophy, like brain.
What label is assigned to proteins that can be degraded? Where are they sent to?
they are marked with ubiquitin. marked proteins are then sent to proteosome for degradation.
T/F ubiquitin labelling requires ATP
true.
the ___ converts amino acids’ amino groups into ___
the liver converts amino groups into urea
What is transamination?
the transfer of amino acids’ amino groups to an ALPHA KETOacid (usually alpha keto glutarate) to yield the alphaketoacid of the original amino acid and a new amino acid.
When amino acids get burned in the muscle, what compound to they get added to? what does this yield?
when the N’s from AA’s get added to pyruvate, which is used to make alanine, which is then sent to the liver.
When amino acids get burned in other tissues besides muscle, what are they turned into?
all amino acids are turned into glutamine before they get sent to the liver.
Where does deamination of glutamate occur? Why is this necessary?
in the mitochondria of the LIVER ONLY. Deamination is necessary in order for alpha keto glutarate to be regenerated, allowing for further breakdown of amino acids.
What molecule must glutamate transfer its amino group to in order to create aspartate?
oxaloacetate
what organ is the urea cycle facilitated in?
the liver
How is carbamoyl phosphate synthetase allosterically regulated?
via acetyl glutamate, which accumulates when urea cycle is too slow, ACTIVATING Carbamoyl phosphatase to go faster
what are glucogenic amino acids
amino acides that are degraded into pyruvate or krebs cycle intermediates (alpha kg, oxa, fumarate) and can MAKE GLUCOSE
What are ketogenic amino acids
amino acids that are degraded into acetyl coA or acetoacetate and thus can be converted into FATTY ACIDS or KETONE BODIES.
Which amino acid is both glucogenic and ketogenic?
tryptophan.
Name the essential amino acids
arginine histidine isoleucine leucine methionine phenylalanine threonine tryptophan valine
Examples of glucogenic amino acids
alanine, serine, cysteine
examples of ketogenic amino acids
lysine
What happens to the carbon skeletons of the degraded amino acids?
form krebs intermediates (glucogenic) or fatty acid/ ketone body intermediates (ketogenic)
draw carbomyl phosphate
see notes
Draw arginosuccinate
see notes
draw urea
see notes
draw ornithine
see notes
draw citrulline
see notes
alternative method to convert glutamate into alphaketoglutarate without oxaloacetate? what enzyme is involved? where does this happen?
glutamate into alphaketoglutarate via glutamate dehydrogenase.this happens in the liver mitochondria
How many atps can a liver cell make from the complete catabolism of Alanine? Draw diagram
16atp per alanine. You need two Alanines to make urea though to begin with. see diagram in notes.
the reduction of NADP+ to NADPH requires ____
a hydride ion
how many ATP equivalents are burned when a cell os undergoing gluconeogenesis
6
What is the key regulated step in the catabolism of free fatty acids in the liver?
trying to transport the fatty acids into the mitochondrial matrix using the carnitine transporter.
describe the metabolic path that oxaloacetate can be metabolized into Co2 and H2o
oxa –> pyr –> acetyl coA —> Krebs.
Where does the oxidative deamination of aspartic acid occur?
no where, only glutamic acid (glutamate) gets oxidatively deaminated. the rest of the amino acids get transaminated to their alpha keto acids, and their nitrogen groups are given to glutmate, which is then deaminated.
what is the redox state for the second carbon in dihydroxyacetone phosphate
2
why are amino acids burned during the early stages of starvation?
because they contain glucogenic amino acids that can be made into glucose.
what does uncoupling of mitochondrial oxidative phosphoyrlation result in?
no atp synthesis, but continued O2 usage.
