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MBC - Lecture 42
Biosynthesis and Turnover of Amino Acids (Douglas)
| Question | Answer |
|---|---|
| Lecture 42 | Biosynthesis and Turnover of Amino Acids |
| ___ and ___ are ketogenic only amino acids. | Leucine and lysine |
| ___ and ___ are non-essential amino acids that require essential precursors. | Tyrosine and tryptophan |
| Sulfur in cysteine is derived from ___. | methionine |
| Urea cycle intermediates in the intestine and kidney are converted to ___ in the ___. | arginine in the kidney |
| Glutamate is reduced to ___ using ATP and NADH. | glutamic semialdehyde |
| Glutamic semialdehyde is formed from ___ by transamination. | ornithine |
| Ornithine is a precursor of ___, ___, and ___. | citrulline, arginine, and proline |
| Glutamic semialdehyde spontaneously cyclizes to ___. | proline |
| ___ is formed from 3-phosphoglycerate by aminotransferase and phosphatase. | Serine |
| Glycine is formed from ___ by hydrolysis and transfer of methyl group to ___. | serine, tetrahydrofolate |
| Serine Hydroxymethyl Transferase | Catalyze interconversion of glycine and serine from threonine |
| Pyridoxal Phosphate | Cofactor used in transaminations and reactions requiring amino transfer |
| Tetrahydrofolate | Folate or vitamin B12, cofactor involved in C1 transfers |
| Tetrahydrobiopterin | Vitamin BH4, cofactor involved in ring hydroxylations |
| Synthesis of cysteine requires condensation of ___ and ___. | homocysteine and serine |
| Cysteine breakdown to ___ involves ___, ___, and ___. | pyruvate involves oxidation, desulfation, and transamination |
| Causes of homocysteinuria: | defective cystathionine synthetase or low B12/FH4/folate levels preventing remethylation of homocysteine |
| Histidine metabolism to glutamate is ___. | unidirectional |
| Role of glutamate in amino acid biosynthesis is to transport ___ to and from ___ in the ___. | carbons to and from glucose in the liver |
| Glutamate carbons from ___ are not from glucose. | histidine |
| Excess ornithine is transaminated to ___, which is oxidized to ___. | glutamate semialdehyde, glutamate |
| ___ and ___ are strictly ketogenic (non-glucogenic). | Leucine and lysine |
| Threonine is metabolized to ___, ___, ___, and ___. | acetyl-CoA, glycine, pyruvate, and propionyl-CoA |
| Propionyl-CoA can be metabolized to ___. | succinyl-CoA |
| Glutamate Dehydrogenase (GDH) | Catalyzes reversible deamination of glutamate to a-ketoglutarate in the liver, using NAD+/NADP+ as a cofactor |
| The major route of glycine metabolism by glycine cleavage enzyme produces ___ and ___, and formation of ___. | CO2 and NH4, and formation of methylene tetrahydrofolate |
| Defects in glycine cleavage enzyme pathway results in ___ and ___. | nonketotic hyperglycinemia and glycine encephalopathy |
| Glycine degradation by ___ leads to glyoxylate then ___. | d-amino acid oxidase, oxalate |
| Oxalate readily forms precipitates with ___ in kidneys to form ___. | calcium, kidney stones |
| Serine metabolism to 3-phosphoglycerate is not a ___ of ___. | reversal of serine synthesis |
| Serine Dehydratase | Pyridoxal phosphate containing enzyme that converts serine to pyruvate |
| Synthesis of S-adenosylmethionine (AdoMet) is from ___ and ___. | methionine and ATP |
| Homocysteine Methyl Transferase | Catalyzes resynthesis of methionine from homocysteine, requires vitamin B12 1C addition |
| Homocysteine has only one ___ route. | degradation |
| Methionine conversion (homocysteine degradation) produces ___. | succinyl-CoA |
| Homocysteinuria | Defective cystathionine synthase or B6 deficiency |
| Lysine is strictly ___, producing ___ when degraded. | ketogenic, acetoacetyl-CoA |
| Branched chain amino acids (BCAA) make up for ___% of protein content. | 25% |
| Branched chain a-keto acids are oxidatively decarboxylated, similar to ___. | pyruvate dehydrogenase |
| Branched chain amino acids oxidized during fasting produces ___ and ___. | energy and glutamine |
| Glutamine and alanine transport ___% of amino acid nitrogen. | 50% |
| Phenylalanine and tyrosine share a common ___. | degradation pathway |
| Phenylketonuria (PKU) results from defects in ___. | phenylalanine dehydroxylase |
| BH4 is used for conversion of ___ to ___. | phenylalanine to tyrosine |
| Phenylalanine hydroxylase or BH4 deficiency leads to accumulation of ___. | phenyl ketones |
| Phenylalanine and tyrosine are degraded to ___ and ___. | fumarate and acetoacetate |
| Fumarylacetoacetase deficiency leads to: | Tyrosinemia I |
| Tyrosine aminotransferase deficiency leads to: | Tyrosinemia II |
| p-hydroxyphenylpyruvate dioxygenase leads to: | Tyrosinemia III |
| Tryptophan metabolism produces: | glutaryl-CoA, alanine, acetyl-CoA, NAD precursors |
| Kynureninase is a ___ containing enzyme that is sensitive to ___ deficiency. | PLP, B6 |
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