Amino Acid Metabolism Flashcards
amino acids are the _____ of proteins
building blocks
some amino acids are converted into _______
acetyl-CoA
What is nitrogen fixation
conversion of N2 to NH3 or NH4+
how to leguminous plants incorporate nitrogen
from bacerially synthesized amino acids into their won
how to nonleguminous plants inorcporoate NH4+
NH4 produced by nitrogen fixing soil bacteria directly into amino acids via nitrogen assimilation
What are the two other nitrogen fixation processes that exist in the biosphere
industrial (the haber process) and atmospheric (lightning)
most often, NH4+ is incorporated into the amino acids ____ and ____
glutamate and glutamine
What are the key enzymes in nitrogen fixation and assimilation
nitrogenase complex, glutamine synthease, glutamate synthase, glutamate dehydrogenase
What does hte nitrogenase complex do
uses redox reaction and ATP hydrolysis to convert N2 and 2NH3 and six redox reactions
What does glutamine synthease do
found in all organisms, incorporates NH4 into glutamate to form glutamine in ATP-redox reaction
What does glutamate synthase do
found in bacteria works with glutamine synthease to replenish glutamate
what does glutamate dehydrogenase do
inconverts glutamate, NH4 and alpha-ketoglutarate using redox reactions
how many redox centers in the nitrogenous complex
six
which amino acids in infected plant cells are synthesized
Glu and Asp
What is the intermediate in the glutamate synthease reaction
y-glutamyl phoshpate
T or F: glutamate synthease reaction requrires ATP hydrolysis
T
What does NH4 assimilation require
glutamine synthease and lgutamate synthase
When can the glutamate dehydrogenase reaction assimilate NH4
when NH4 concentration are very high
degredation of eukaryotic cellular protein is mediated by _____ and ____
lysosomes nad proteases
How to lysosomes degrade proteins
contain acidic proteases that digest protein particles delivered by phagocytosis
how to proteases degrade proteins
using three different protease activities located within the central core
what is nitrogen used for in mammals
for urea or biosynthetic pathways
what happens to the remaining carbon skeletons in mammals
metabolized to create ATP, glucose, fatty acids or ketone bodies
amino acids transported to the liver use nitrogen to make _____
urea
what does the alanine glucose cycle to for cells
removes excess nitrogen from muscles, using alanine as the carrier
The urea cycle consists of ___ enzymatic reactions
5
How many of the enzymatic reactions in the urea cycle occur in the cytosol
3/5
where is the carbon in urea dervied from
HCO3- from citrate cycle
What is the aspartate-arginosuccinate shunt
connects urea and the citrate cycle
what connects urea and the citrate cycle
fumarate is used to make aspartate in the mitochondrial matrix
what are gluconeogenic amino acids
have carbon skeletons that can be used to synthesize glucose
what are ketogenic amino acids
give rise to acetyl-CoA and acetoacetyl-CoA which are precursors to keton bodies
what is the difference between essential and nonessential amino acids
essential amino acids are more complex and take a greater number of enzymatic steps to synthesize
what is the herbicide glycophosphate
blocks amino acid synthesis in plants by inhibiting the activity of EPSP synthase
GLycophosphate is an _______ inhibitor of phophoeonol pyruvate
competitive
what are hemes
hemoglobin and cytochromes
what are nucleotides
purines and pyridimines
what are signaling molecules
neurotransmitters, hormones and nitric oxide
What is glycine
contributes the four nitrogen atoms to heme in a series of reactions that take place in both the matrix and cytosol
What does tyrosine do
is the metabolic precursor to dopamine, norepinephrine and epinephrine
What is tetrahydrobiopterin
key redox cofactor in a variety of amino acid metabolic pathways
what does nitric oxide synthase do
uses a two step reaction to generate the vasodialator nitric oxide from arganine using O2 and NADPH
nitric oxide leads to the relaxation of what
smooth muscle cells and blood vessel dialation
nitroglycerin is what?
used to treat angina cause by vasoconstriction of cardiac blood vessels
