Chapter 21: Amino Acid Metabolism Flashcards
Why are amino acids unique?
Only macromolecule containing nitrogen.
Do amino acids get stored in the cell?
No
What are AA converted into?
Not excreted. There are converted into common metabolites such as precursors to glucose, fatty acids, and ketone bodies.
What are proteins denatured for? (3)
1) To store nutrients in the form of proteins and to break them down in times of metabolic need, processes that are especially important to muscles.
2) To eliminate abnormal proteins to prevent accumulation.
3) To permit the regulation of cellular metabolism by eliminating superfluous
enzymes and regulatory proteins.
What do lysosomes do?
Carry out autophagy (nonselective degradation)
Under starvation conditions, lysosomes may be selective
Where else can protein degradation occur outside lysosomes?
Ubiquitin, a protein
Covalently linking proteins to ubiquitin will do what?
Mark them for degradation.
For degradation to occur, ubiquitinated proteins ______
must be linked together.
1st transamination reaction:
2nd transamination reaction:
Can glutamate be deaminated?
Yes, by glutamate dehydrogenase to yield ammonia and a-ketoglutarate
Ammonia + Asparate = ?
Urea + Fumarate
1st committed step of urea cycle?
To make carbamoyl phosphate.
Catalyzed my carbamoyl phosphate synthetase I
Component needed to make carbamoyl phosphate?
N-acetylglutamate
Synthesized my glutamate and acetyl-coA. Catalyzed by N-acetylglutamate synthase.
Why does glutamate increase when amino acid breakdown increases?
Increases glutamate stimulates N-acetylglutamate synthesis, which results in activation of carbamoyl phosphate synthetase to increase urea production.
Strictly ketogenic amino acids:
Lysine and leucine
General ketogenic amino acids:
- leucine
- lysine
- isoleucine
- threonine
- phenylalanine
- tryptophan
- tyrosine
Amphibolic amino acids:
- phenylalanine
- isoleucine
- threonine
- tryptophan
- tyrosine
Glucogenic amino acids:
- alanine
- arginine
- asparagine
- aspartic acid
- cysteine
- glutamic acid
- glutamine
- glycine
- histidine
- methionine
- proline
- serine
- valine
Amino acids that are degraded to pyruvate?
Alanine, cysteine, glycine, serine, and threonine.
Amino acids that are degraded to oxaloacetate?
Asparagine and aspartate.
- by means of transamination
Amino acids that are degraded to a-ketoglutarate?
Arginine, glutamate, glutamine, histidine, and proline.
Amino acids that are degraded to succinyl-CoA?
Methionine, threonine, isoleucine, and valine.
Degradation of branched chain amino acids involved Acyl-CoA Oxidation?
- transamination to corresponding a-keto acid
- oxidative decarboxylation to the corresponding acyl-CoA
- dehydration by FAD to form a double bond
