Lecture 22 - Folate, B12, and Non-Essential Amino Acids

Question 1

Name 3 carriers of one-carbon units.

Answer 1

1. THF
2. Formic acid
3. SAM

Question 2

Biotin carries the carboxylate group, which is the _________ oxidized carbon.

A. Most
B. Least

Answer 2

A

Question 3

SAM carries the _________ type of carbons.

A. Most reduced
B. Most oxidized
C. Neither A or B

Answer 3

A

Question 4

What are 3 biosynthetic pathways that require one carbon units?

Answer 4

A. Synthesis of non-essential amino acids
B. Synthesis of purines
C. Synthesis of pyrimidines

Question 5

SAM is involved in the synthesis of which of the following molecules?

A. Creatine
B. Carnitine
C. Epinephrine
D. Methylated DNA and RNA
E. All of the above

Answer 5

E

Question 6

What is “SAM” the “preferred carrier” of?

Answer 6

Activated methyl carrier

Question 7

9 of 11 of the non-essential AAs are synthesized form intermediates in __________ or ________.

Answer 7

1. glycolysis

2. TCA cycle

Question 8

___________ is the process of an amino group changing to a ketoacid.

Answer 8

Transamination

Question 9

Enzymates that catalyze the formation of an amide bond are usually called:

Answer 9

synthetases

Question 10

Glutamate can form what 3 amino acids?

Answer 10

1. Proline
2. Arginine
3. Glutamine

Question 11

Which glycolytic intermediate forms alanine, a non-essential amino acid?

Answer 11

Pyruvate

Question 12

Name 2 non-essential amino acids are synthesized from essential amino acids.

Answer 12

1. Tyrosine

2. Cysteine

Question 13

Cysteine is formed from _________.

Answer 13

methionine

Question 14

Tyrosine is formed from __________.

Answer 14

phenylalanine

Question 15

Maternal PKU is caused by damage to fetus by ___________.

Answer 15

maternal phenylketones (formed when tyrosine can’t be synthesized)

Question 16

Classical PKU presents with a deficiency in ___________.

Answer 16

Phenylalanine hydroxylase

Question 17

If untreated, all 3 PKU lead to severe mental retardation. This is due to decreased transport of ______ and __________ across the blood brain barrier.

Answer 17

1. tyrosine

2. tryptophan

Question 18

What are the consequences of a folic acid deficiency?

Answer 18

Inability to carry all one-carbon groups (except methyl); impaired synthesis of compounds that requrie one-carbon units

Question 19

What two reactions in humans require Vitamin B12?

Answer 19

1. Conversion of L-methylmalonyl-CoA to succinyl-CoA in BCAA metabolism
2. Remethylation of SAM requires Vitamin B12

Question 20

How does a B12 deficiency result in secondary folate deficiency?

Answer 20

B12 required for conversion of 5-Methyl-THF to THF; so without B12, 5-Methyl-THF builds up and you don’t have any usable folate.

Question 21

_________ is is an amino acid whose plasma concentration is an indicator of functional small intestinal masses.

Answer 21

Citrulline

Question 22

Homocysteine can be used to regenerate ______, an essential amino acid.

Answer 22

methionine

Question 23

Homocysteine can be used to synthesize ______, a non-essential amino acid.

Answer 23

cysteine

Question 24

Taurine can be made from _____.

Answer 24

cysteine