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30 Cards in this Set
- Front
- Back
Pepsin
A- is a zymogen B- requires the action of the hormone gastrin to be active C- is the most activate at pH 7.0 D- cleaves proteins completely into free amino acids |
B
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Gastrin stimulates the secretion of hycholric acid into the stomach, creating a very acidic environment that is optimal for the activity of _______
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pepsin
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In addition, the low pH acts as a denaturing agent, unfolding globular proteins and making their internal peptide bonds more accessible to the enzymatic hydrolysis of pepsin
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yep
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The urea cycle
A- takes place in the mitochondrial matrix of hepatocytes B- generats ATP C- starts with the entry of ornithine D- converts ammonia to urea |
D
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the urea cycle converts ammonia in the form of _________ ______ into urea
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carbamoyl phosphate
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Ammonia CANNOT be transported in the blood as
A- urea B- glutamate C- alanine D- glutamine |
B
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Glutamate is strictly an intracellular carrier of ammonia. In mucles and other tissues that degrade amino acids for fuel, amino groups are collected in the form of ______, which can be converted to ______ or _______ for transport to the liver
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glutamate
glutamine alanine |
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In which of the following organisms is the amino nitrogen from amino acids excreted as uric acid?
A- eagels B- zebra fish C- daffodils D- Rats |
A
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birds and reptiles excrete amino nitrogen as ___ ____ and are therefore called uricotelic animals
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uric acid.
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the glucose-alanine cycle involves
A- the linking of gluconeognesis and glycolysis in the liver B- transfer of the amino group from alanine to glutamate to form glutamine in the liver C- the transport of pyruvate by alanine D- the passing of alanine back and forth between the liver and sk. mm |
C
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vigorously contracting skeletal muscles operate anaerobically, producing _______ from glycolysis as well as __________ from protein breakdown. Both of these products are eliminated from the muscle by being combined to form _________, which is transported in the blood to the _______
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pyruvate
ammonia alanine liver |
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in what way are the TCA and the urea cycles linked?
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Fumarate generated in the urea cycle is used in the TCA.
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which types of amino acids are both ketogenic and glucogenic?
A- those that are degraded to succinyl-CoA B- those that are degraded to pyruvate C- those that are degraded to oxaloacetate D- those that are degraded to acetyl-CoA |
B
pyruvate can be converted to either acetyl-CoA (a ketone body precursor ) or oxaloacetate (a precursor for gluconeogenesis) |
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what types of amino acids are ketogenic?
A- those that are degraded to fumarate B- those that are degraded to succinyl-CoA C- Those that are degraded to acetyl-CoA those that are degraded to alpha-ketoglutarate |
C
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which of the following amino acids is degraded in the liver?
A- Isoleucine B- Valine C- Threonine D- Leucine |
C
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All ____ _____ chain amion acids are degraded in the liver. The branched-chain amino acids ( ______, _______, _______) are degraded in _____________ tissues such as muscle, adipose, kidney, and brain tissue.
This is because the aminotransferase that converts all three branched-cahin amion acids to their corresponding alpha-keto acids is ______ in liver |
non-branched
leucine, isoleucine, valine extrahepatic absent |
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The cofactor S-adenosylmethionine (adoMet) transfers
A- CO2 B- Methyl groups C- methionine D- adensyl groups |
B
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the role of pyridoxal phosphate (PLP) is...
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as an intermediate carrier of amino groups.
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what do the peptidases trypsin, chymotrypsin, and carboxypeptiase A have in common?
A- they cleave peptides at specific amino acid residues B- They are activated by enteropeptidase C- they cleave their own zymgens D- They digest peptides in the intestine |
D
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The reactions catalyzed by aminotransferases
A- require a ketoglutarate as an amino group acceptro B- generate free ammonia C- involve two substrates D- are highly exergonic |
C
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aminotransferase rxns are typical bimolecular ping-pong reactions, in which the first subsrate reacts and the product must leave the active site before the ________ substrate can bind
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second
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which enzyme DOES NOT participate in the transfer pathway of nitrogen from ALL amino acids to urea?
A- glutaminase B- glutamate dehydrogenase C- arginase D- aspartate aminotransferae |
A
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glutaminase cleaves the amide group from glutamine, generating _____ and ________. Ammonia is the incorporated into urea via carbamoyl phosphate. Therefore, glutaminase will only participate in the transfer of nitrogen from glutamine to urea
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glutamate
ammonia |
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which of the following amino acids can be converted to alpha-ketoglutarate?
A- aspartate B- leucine C- methionine D- proline |
D
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people with a defective tyrosinase gene suffer from
a- kidney stones B- malple srup urine disease C- PKU D- lack of pigmentatoin |
D
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which of the following is TRUE about ALL amino acids?
A- Degradation generates products that can enter the TCA B- they cannot be synthesized by humans C- the first step of catabolsim is the removal of the alpha-amino group D- they can be stored |
A
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the branched-chain alpha-keto acid dehydrogenase complex
A- requires coenzmye A as a cofactor B- catalyzes oxidative deamination C- generates alpha-keto acids D- transfers carboxyl groups to the other molecule |
A
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the branched-chain alpha-keto acid dehydrogenase complex catalyzes oxidative decarboxylation of branched-chian alpha keto acids, releasing the carboxyl group as ____ and producing the acyl-coA derivative. This reaction, which is analogous to the oxidative decarboxylation of pyruvate to acetyl-CoA by pruvate dehydrogenase, requires ____ ___ as a cofactor
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CO2
coenzyme A |
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what is Uricotelic?
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excreting excess nitrogen in the form of urate (uric acid)
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what is ureotelic?
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excreting excess nitrogen in the form of urea
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