single carbon metabolism - Exam 1

Question 1

What is the methyl dinner for almost all methylation reactions in the body?

Answer 1

SAM
s-adenosylmethionine
adoMet

Question 2

SAM breaks down to

Answer 2

s-Adenosyl-homocysteine

will break down into adenosine and homocysteine

Question 3

elevated homocysteine correlate with…

Answer 3

heart disease, hypertension, and stroke

Question 4

required to make methionine (co-enzymes)

Answer 4

tetrahydrofolate coenzyme B12
and
n5-methyltetrahydrofolate, from folic acid

Question 5

main source of one carbon groups

Answer 5

Serine

Question 6

homocysteine used to make

Answer 6

methionine

Question 7

methyl trap?

Answer 7

n5-THF can only transfer to b12
so no B12 causes:
accumulation of n5-THF and
deficiency of folate (broken down to make n5-THF)

Question 8

lack of folate results in

Answer 8

suppressed DNA synthesis

Question 9

commercial B12 has what group?

Answer 9

-CN
or -OH
hydroxy-B12 can be used to treat CN poisoning

Question 10

reactions that B12 can do

Answer 10

Methionine or Succinyl CoA

Question 11

MMA?

Answer 11

defect in MMCoA mutase or B12 def
can’t make Succinyl-CoA so MMA accumulates
vomiting, convulsions, retardation, early death
any in urine is probably B12 def if suspected

Question 12

B12 transport

Answer 12

binds low pH
releases high pH, picked up by intrinsic factor
brought in - half stored AND half used

Question 13

pernicious anemia

Answer 13

megaloblastic
lack of intrinsic factor
usual signs PLUS tingling and numbness
can cause neurologic problems

Question 14

megaloblastic anemia is often..

Answer 14

def in B12 or Folate.
tx with both

Question 15

transsulfuration

Answer 15

makes cysteine from homocysteine and serine
requires B6
enzyme def will be homocystienuria

Question 16

glutathione is the major intracellular redox buffer while ____ is the major extracellular redox buffer.

Answer 16

Cysteine

both free and bound?

Question 17

homocysteine in blood or urine

Answer 17

dislocation of lens
skeletal
retard
increased risk of blood clots
tx with B6,B12,folate and restricting methionine

Question 18

minor pathway for methionine production

Answer 18

in liver from homocysteine using betaine

Question 19

biotin

Answer 19

required by carboxylases