Amino Acids

Question 1

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

Answer 1

ketone bodies

Question 2

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

Answer 2

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

Question 3

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

Answer 3

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

Question 4

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

Answer 4

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

Question 5

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

Answer 5

True

Question 6

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

Valine

Alanine

Leucine

Isoleucine

Answer 6

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

Question 7

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

Answer 7

True

Question 8

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

Answer 8

True

Question 9

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.

Answer 9

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

Question 10

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

Answer 10

True

Question 11

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

Answer 11

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

Question 12

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

Answer 12

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

Question 13

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

Answer 13

True

Question 14

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

Answer 14

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

Question 15

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

Answer 15

True

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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

Question 18

Which of the following catalyzes ring hydroxylations?

PLP

BH4

FH4

Answer 18

BH4, AKA tetrahydrobiopterin

Question 19

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

PLP

BH4

FH4

Answer 19

FH4, AKA tetrahydrofolate

Question 20

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

PLP
BH4

FH4

Answer 20

PLP, AKA pyridoxal phosphate

Question 21

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

Answer 21

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

Question 22

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

Answer 22

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

Question 23

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

Answer 23

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

Question 24

Which of the following is NOT an essential amino acid?

Phenylalanine

Valine

Threonine

Tyrosine

Isoleucine

Methionine

Histidine

Arginine

Leucine

Lysine

Answer 24

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

Phenylalanine

Valine

Threonine

Tryptophan

Isoleucine

Methionine

Histidine

Arginine

Leucine

Lysine

Question 25

\_\_\_ is the only nonessential amino acid that is both ketogenic and glucogenic

Answer 25

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

Question 26

\_\_ and __ are ketogenic essential amino acids

Answer 26

_Leucine_ and _lysine_ are ketogenic essential amino acids (phenylalanine, isoleucine and tryptophan are both glucogenic and ketogenic essential amino acids)

Question 27

methionine can be utilized to make the nonessential amino acid \_\_

Answer 27

cysteine

Question 28

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

Answer 28

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

Question 29

\_\_\_ is the major source of carbons for the "one carbon pool"

Answer 29

_Serine_ is the major source of carbons for the "one carbon pool"

Question 30

Which of the following amino acids is NOT converted to the TCA cycle intermediate succinyl CoA? Isoleucine Proline Methionine Threonine Valine

Answer 30

Proline; it's converted to alpha ketoglutarate

Question 31

Which of the following intermediates is ketogenic? Acetyl CoA Oxaloacetate Alpha ketoglutarate Succinyl CoA Fumarate

Answer 31

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

Question 32

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

Answer 32

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

Question 33

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

Answer 33

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)

Question 34

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

Answer 34

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

Question 35

Which of the following is nonessential amino acids is both ketogenic and glucogenic? alanine aspartate asparagine cysteine glutamate glutamine glycine proline serine tyrosine

Answer 35

Tyrosine is the only nonessential amino acid that is both ketogenic and glucogenic. the rest are only glucogenic: ## Footnote alanine, aspartate, asparagine, cysteine, glutamate, glutamine, glycine, proline, and serine

Question 36

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

Answer 36

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

Question 37

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

Answer 37

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

Question 38

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

Answer 38

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

Question 39

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

Answer 39

True

Question 40

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

Answer 40

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

Question 41

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

Answer 41

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

Question 42

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

Answer 42

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 (O**_AA_**--from **_A_**spartate & **_A_**sparagine)

Question 43

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

Answer 43

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

Question 44

Which branched chain amino acid is both glucogenic and ketogenic? valine leucine isoleucine

Answer 44

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

Question 45

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

Answer 45

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

Question 46

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

Answer 46

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

Question 47

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 \_\_.

Answer 47

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)_.

Question 48

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

Answer 48

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_.

Question 49

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 \_\_\_.

Answer 49

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_.

Question 50

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

Answer 50

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

Question 51

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

Answer 51

True

Question 52

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

Answer 52

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

Question 53

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

Answer 53

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

Question 54

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.

Answer 54

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.