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Post Midterm GI Biochem > Amino Acids > Flashcards

Amino Acids Flashcards

1
Q

NH3 is toxic yet a vital blood buffer during a long fast due to its ability to help neutralize ___

A

ketone bodies

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2
Q

T/F: citrate, isocitrate and alpha ketoglutarate are all able to be used as fuels and during TCA cycling are oxidized to succinate and ultimately broken down to CO2 and H2O

A

False. Once they are oxidized to succinate, succinate will only recycle. Only way to reduce succinate is for it to LEAVE TCA cycle, get converted to Acetyl CoA, and then re-enter the cycle

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3
Q

T/F: glutaminase converts glutamate to alpha ketoglutarate via removal of an NH4+ in the kidney

A

False. glutaminase converts glutamine to glutamate, removing an NH4+. glutamate is converted to alpha ketoglutarate via glutamate dehydrogenase which removes an NH4+

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4
Q

T/F: Pyruvate is converted to Alanine via a transaminase, which in turn removes an NH3 from alpha ketoglutarate to make glutamate

A

False. pyruvate is converted to alanine via a transaminase, but it removes an NH3 from GLUTAMATE to make ALPHA KETOGLUTARATE

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5
Q

T/F: in extremes of starvation, gluconeogenesis occurs in the renal cortex

A

True

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6
Q

Which of the following is NOT a branched chain amino acid?

Valine

Alanine

Leucine

Isoleucine

A

Alanine. Valine, Leucine and Isoleucine are all branched chain amino acids

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7
Q

T/F: in the liver, ammonia is removed from alanine to create pyruvate

A

True

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8
Q

T/F: in muscle, NH3 is removed from branched chain amino acids and added to pyruvate to generate alanine

A

True

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9
Q

T/F: BCAAs are oxidized in the muscle to form succinyl CoA and acetyl CoA. A lot of the succinyl CoA is converted to glutamate and alanine for export.

A

False. A lot of the succinyl CoA generated is converted to GLUTAMINE and alanine for export

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10
Q

T/F: due to rapid cell turnover in the gut, an ample supply of glutamine is needed for purine/pyrimidine synthesis

A

True

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11
Q

T/F: during ammonia toxicity, excess NH3 shifts the Glutamate/Glutamine balance towards glutamate, causing a loss of glutamine, a key neurotransmitter

A

False. During ammonia toxicity, excess NH3 shifts the Glutamate/Glutamine balance towards GLUTAMINE, causing a loss of GLUTAMATE, a key neurotransmitter

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12
Q

T/F: during ammonia toxicity, the excess glutamine leaves the mitochondria of astrocytes into the cytoplasm where it is hydrolyzed to glutamate and NH3, increasing formation of ROS

A

False. during ammonia toxicity, the excess glutamine ENTERS the mitochondria of astrocytes where it is hydrolyzed to glutamate and NH3, increasing formation of ROS.

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13
Q

T/F: after a high protein diet, branched chain amino acids are taken in by skeletal muscle in response to insulin and used for protein synthesis

A

True

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14
Q

T/F: In order to fight infection, increased glucocorticoids (cortisol) cause a decrease in protein breakdown in muscle, increase in protein synthesis in muscle, an increase in lipolysis in adipose tissue, and an increased breakdown of glycogen in the liver

A

False. In order to fight infection, increased glucocorticoids (cortisol) cause an INCREASE in protein breakdown in muscle, DECREASE in protein synthesis in muscle, an increase in lipolysis in adipose tissue, and an increased breakdown of glycogen in the liver

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15
Q

T/F: during sepsis/trauma, glutamine is sent from muscle to be used to remove NH3 via the kidneys and to the liver to be used to generate acute phase proteins

A

True

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16
Q

Maple Syrup Urine Disease is caused by a deficiency in the enzyme ___

A

branched chain alpha keto acid dehydrogenase, which is used in the breakdown of valine, leucine, and isoleucine

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17
Q

In ____, the deficiency of phenylalanine hydroxylase causes an accumulation of ____.

A

In PKU (phenylketonuria), the deficiency of phenylalanine hydroxylase causes an accumulation of phenylalanine.

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18
Q

Which of the following catalyzes ring hydroxylations?

PLP

BH4

FH4

A

BH4, AKA tetrahydrobiopterin

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19
Q

Which of the following cofactors, part of the one carbon pool, transfers Cs during various states of oxidation?

PLP

BH4

FH4

A

FH4, AKA tetrahydrofolate

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20
Q

Which of the following cofactors is a quintessential coenzyme found in over 10 different types of reactions?

PLP
BH4

FH4

A

PLP, AKA pyridoxal phosphate

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21
Q

The C-skeleton of an ____ amino acid can be converted to pyruvate and TCA cycle intermediates.

A

The C-skeleton of a glucogenic amino acid can be converted to gluconeogenic intermediates like pyruvate and TCA cycle intermediates.

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22
Q

the C-skeleton of a ketogenic amino acid cannot be converted into a gluconeogenic intermediate with the exception of _,_,_, and _

A

the C-skeleton of a ketogenic amino acid cannot be converted into a gluconeogenic intermediate with the exception of tyrosine, isoleucine, phenylalanine and tryptophan. These amino acids are both ketogenic and glucogenic

23
Q

T/F: Arginine is synthesized at a rate adequate to support growth of children.

A

False. Arginine is a nutritionally semi-essential amino acid. It is not synthesized at a rate to adequately support growth of children.

24
Q

Which of the following is NOT an essential amino acid?

Phenylalanine

Valine

Threonine

Tyrosine

Isoleucine

Methionine

Histidine

Arginine

Leucine

Lysine

A

Tyrosine. Phenylalanine can be used to generate Tyrosine. Essential amino acids are:

Phenylalanine

Valine

Threonine

Tryptophan

Isoleucine

Methionine

Histidine

Arginine

Leucine

Lysine

25
Q

___ is the only nonessential amino acid that is both ketogenic and glucogenic

A

Tyrosine is the only nonessential amino acid that is both ketogenic and glucogenic

26
Q

__ and __ are ketogenic essential amino acids

A

Leucine and lysine are ketogenic essential amino acids (phenylalanine, isoleucine and tryptophan are both glucogenic and ketogenic essential amino acids)

27
Q

methionine can be utilized to make the nonessential amino acid __

A

cysteine

28
Q

Phenylalanine is converted to the amino acid ___ via the phenylalanine hydroxylase enzyme

A

Phenylalanine is converted to the amino acid tyrosine via the phenylalanine hydroxylase enzyme

29
Q

___ is the major source of carbons for the “one carbon pool”

A

Serine is the major source of carbons for the “one carbon pool”

30
Q

Which of the following amino acids is NOT converted to the TCA cycle intermediate succinyl CoA?

Isoleucine

Proline

Methionine

Threonine

Valine

A

Proline; it’s converted to alpha ketoglutarate

31
Q

Which of the following intermediates is ketogenic?

Acetyl CoA

Oxaloacetate

Alpha ketoglutarate

Succinyl CoA

Fumarate

A

Acetyl CoA. This and acetoacetate are ketogenic (pyruvate is an intermediate that can make acetyl CoA, but is considered a glucogenic intermediate)

32
Q

Phenylalanine and Tyrosine are both ketogenic and glucogenic, and both create the intermediates __ (glucogenic) and __ (ketogenic)

A

Phenylalanine and Tyrosine are both ketogenic and glucogenic, and both create the intermediates fumarate (glucogenic) and acetoacetate (ketogenic)

33
Q

Isoleucine is both ketogenic and glucogenic, creating the ketogenic intermediate _ and the glucogenic intermediate _

A

Isoleucine is both ketogenic and glucogenic, creating the ketogenic intermediate acetyl CoA and the glucogenic intermediate succinyl CoA (methionine, valine and threonine also make this intermediate)

34
Q

Arginine, histidine (both essential) and proline (nonessential) can be used to create the glucogenic intermediate __ but must first be converted to glutamate

A

Arginine, histidine (both essential) and proline (nonessential) can be used to create the glucogenic intermediate alpha ketoglutarate but must first be converted to glutamate

35
Q

Which of the following is nonessential amino acids is both ketogenic and glucogenic?

alanine

aspartate

asparagine

cysteine

glutamate

glutamine

glycine

proline

serine

tyrosine

A

Tyrosine is the only nonessential amino acid that is both ketogenic and glucogenic. the rest are only glucogenic:

alanine, aspartate, asparagine, cysteine, glutamate, glutamine, glycine, proline, and serine

36
Q

Maple Syrup Urine Disease is an autosomal recessive disease caused by mutations in branched chain alpha ketoacid dehydrogenase (BCKDH). BCKDH, a mitochondrial enzyme complex, is comprised of three subunits. Which subunit is thiamine dependent?

E1 decarboxylase

E2 transacylase

E3 dehydrogenase

A

E1 decarboxylase, a heterotetramer composed of alpha and beta subunits, is thiamine dependent. they emphasized this in the lecture.

37
Q

Asparagine and Aspartate are both nonessential glucogenic amino acids, entering the TCA cycle via the intermediate ___

A

Asparagine and Aspartate are both nonessential glucogenic amino acids, entering the TCA cycle via the intermediate oxaloacetate

38
Q

Alanine, cysteine, glycine, serine, threonine and tryptophan all commonly produce the glucogenic intermediate ___

A

Alanine, cysteine, glycine, serine, threonine and tryptophan all commonly produce the glucogenic intermediate pyruvate

39
Q

T/F: arginine, histidine, methionine, threonine and valine are all essential amino acids that are only glucogenic

A

True

40
Q

Glutamate semialdehyde can be used to produce the nonessential amino acids _ and _

A

Glutamate semialdehyde can be used to produce the nonessential amino acids Proline and Arginine

41
Q

___ is used to make norepinephrine, epinephrine, melanin, DOPA and body protein

A

Tyrosine is used to make norepinephrine, epinephrine, melanin, DOPA and body protein

42
Q

Which of the following is NOT an amphibolic intermediate generated from amino acid metabolism?

pyruvate

acetoacetate

acetyl coa

citrate

alpha ketoglutarate

succinyl coa

fumarate

oxaloacetate

A

citrate is not an amphibolic intermediate. There are seven:

pyruvate (alanine, cysteine, glycine, serine, threonine, tryptophan)

acetoacetate (leucine, lysine, phenylalanine, tryptophan, tyrosine)

acetyl coa (isoleucine)

alpha ketoglutarate (proline, arginine, histidine; glutamine/glutamate)

succinyl coa (isoleucine, methionine, valine, threonine)

fumarate (phenylalanine, tyrosine)

oxaloacetate (OAA–from Aspartate & Asparagine)

43
Q

Alkaptonuria, a disease of phenylalanine metabolism caused by a deficiency in functional ___, causes an accumulation of ___, which leads to arthritis and black urine

A

Alkaptonuria, a disease of phenylalanine metabolism caused by a deficiency in functional homogentisate oxidase, causes an accumulation of homogentisic acid, which leads to arthritis and black urine

44
Q

Which branched chain amino acid is both glucogenic and ketogenic?

valine

leucine

isoleucine

A

isoleucine is both ketogenic and glucogenic. valine is only glucogenic, and leucine is only ketogenic.

45
Q

Serine, a major carbon group source for the one carbon pool, generates __ with PLP, FH4 and serine hydroxymethyl transferase

A

Serine, a major carbon group source for the one carbon pool, generates glycine with PLP, FH4 and serine hydroxymethyl transferase

46
Q

In the fifth and final step of the urea cycle, arginine is converted to __, giving off __ by the enzyme arginase.

A

In the fifth and final step of the urea cycle, arginine is converted to ornithine, giving off Urea by the enzyme arginase.

47
Q

In the first step of the urea cycle, bicarbonate and ammonium are converted to carbamoyl phosphate in the mitochondria with the help of 2 ATP and the enzyme __.

A

In the first step of the urea cycle, bicarbonate and ammonium are converted to carbamoyl phosphate in the mitochondria with the help of 2 ATP and the enzyme carbamoyl phosphate synthetase I (CPSI).

48
Q

In the second step of the urea cycle, carbamoyl phosphate donates an amine group to ornithine in the mitochondrion, generating citrulline via the enzyme ___.

A

In the second step of the urea cycle, carbamoyl phosphate donates an amine group to ornithine in the mitochondrion, generating citrulline via the enzyme ornithine transcarbamoylase.

49
Q

In the third step of the urea cycle, after citrulline leaves the mitochondrion, it is converted to argininosuccinate with the help of aspartate, ATP and the enzyme ___.

A

In the third step of the urea cycle, after citrulline leaves the mitochondrion, it is converted to argininosuccinate with the help of aspartate, an ATP and the enzyme argininosuccinate synthetase.

50
Q

In the fourth step of the urea cycle, argininosuccinate releases fumarate and becomes arginine via the enzyme __.

A

In the fourth step of the urea cycle, argininosuccinate releases fumarate and becomes arginine via the enzyme argininosuccinate lyase.

51
Q

T/F: glutamine can be used as fuel for the gut, kidney and immune cells

A

True

52
Q

glutamine serves two functions in the kidney, (1) to generate ___ to buffer blood, and (2) (from glutamate) to generate ___ to buffer blood and ___ for energy

A

glutamine serves two functions in the kidney, (1) to generate NH4+ to buffer blood, and (2) (from glutamate) to generate NH4+ and alpha ketoglutarate for energy

53
Q

_____ toxicity causes cerebral edema, seizures, somnolence, apnea, and even a coma

A

Ammonia toxicity causes cerebral edema, seizures, somnolence, apnea, and even a coma

54
Q

After consumption of a high carbohydrate meal, there is a 12-fold __ in insulin, and a 1.4-fold __ in glucagon.

After consumption of a high protein meal, there is a 2.5-fold __ in insulin, and a 1.67-fold __ in glucagon.

A

After consumption of a high carbohydrate meal, there is a 12-fold increase in insulin, and a 1.4-fold decrease in glucagon.

After consumption of a high protein meal, there is a 2.5-fold increase in insulin, and a 1.67-fold increase in glucagon.

Post Midterm GI Biochem (1 decks)

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