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IHN: Biochemistry 2 > TBL: choline > Flashcards

TBL: choline Flashcards

1
Q

the gene for the enzyme that catalyzes choline biosynthesis is induced by

A

estrogen

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2
Q

choline 3 functions

A
  1. source of methyl groups for SAM
  2. acetylcholine
  3. part of main phospholipid in membranes
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3
Q

dietary sources of choline

A

eggs
liver
wheat germ (membrane rich components)

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4
Q

betaine is a

A

choline metabolite

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5
Q

betaine can’t be converted to __ but can be used as a __, sparing some __

A

betaine can’t be converted to choline but can be used as a methyl donor, sparing some choline requirements

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6
Q

good source of betaine

A

beets

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7
Q

is human breast milk rich in choline?

A

YES

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8
Q

__ degrade choline to make __ and __ before it can be absorbed

A

gut bacteria degrade choline to make betaine and methylamines before it can be absorbed

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9
Q

free choline that survives the gut bacteria is absorbed by the __ by __ transport

A

free choline that survives the gut bacteria is absorbed by the intestine by carrier-mediated transport

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10
Q

what 2 items contain enzymes that hydrolyze phosphoatidylcholine in the diet

A

pancreatic secretions
intestinal mucosal cells

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11
Q

what enzyme hydrolyzes phosphatidylcholine

A

phospholipases (A1, A2, and B)

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12
Q

after hydrolyzing phsophatidylcholine, the free choline formed enters __

A

after hydrolyzing phsophatidylcholine, the free choline formed enters portal circulation of the liver

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13
Q

how is choline transported to the placenta?

A

in large amounts, choline is pumped against a concentration gradient

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14
Q

all tissues accumulate choline by __ and __

A

all tissues accumulate choline by diffusion and mediated transport

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15
Q

choline uptake is especially important in (5 tissues)

A
  1. liver
  2. kidney
  3. mammary gland
  4. placenta
  5. brain
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16
Q

only a small fraction of dietary choline is __ by __

A

only a small fraction of dietary choline is acetylated by choline acetyltransferase

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17
Q

availability of __ and __ influence choline acetyltransferase activity

A

availability of choline and CoA influence choline acetyltransferase activity

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18
Q

in the brain, what determines the rate of acetylcholine synthesis and why

A

choline availiability bc it is unlikely for choline acetyltranferase to be saturated

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19
Q

choline taken up by the brain may firest enter a __ before it is converted to __

A

choline taken up by the brain may firest enter a storage pool before it is converted to acetylcholine

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20
Q

methyl groups of choline can be used for (2)

A
  1. one-carbon metabolism
  2. conversion to betaine
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21
Q

main sites of choline oxidation

A

liver and kidney

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22
Q

purpose of choline oxidation

A
  1. decrease choline availability to tissues
  2. scavenges methyl groups
  3. ATP generation
23
Q

in utero, fetus is exposed to __ concentrations of choline

A

in utero, fetus is exposed to high concentrations of choline

24
Q

__ is one of the few non-nervous tissues to store large amounts of choline as __

A

placenta is one of the few non-nervous tissues to store large amounts of choline as acetylcholine

25
choline acetyltransferase acetyaltes a __ fraction of dietary choline
choline acetyltransferase acetyaltes a **small** fraction of dietary choline
26
choline acetyltransferase is concentrated in __ and __
choline acetyltransferase is concentrated in **cholinergic neurons** and **placenta**
27
choline acetyltransferase depends on availabilityof (2)
1. choline 2. CoA
28
large precursor pool of choline used for acetylcholine synthesis is found in __ in cholinergic neurons
large precursor pool of choline used for acetylcholine synthesis is found in **choline phospholipids** in cholinergic neurons
29
main sites of choline oxidation
liver and kidney
30
choline oxidation forms __
choline oxidation forms **betaine**
31
oxidation of choline steps
1. Choline is oxidized to Betaine aldehyde in the inner mitochondrial membrane 2. Betaine aldehyde dehydrogenase oxidizes betaine aldehyde to form betaine. 3. Betaine cannot be reduced back to choline; oxidation pathway diminishes availability of choline
32
mice without choline dehydrogenase couldn't produce
ATP
33
making phosphatidylcholine: enzyme 1
choline kinase
34
making phosphatidylcholine: enzyme 2
CTP PC
35
rate limiting step in phosphatidylcholine biosynthesis
CTP PC
36
deficiency of CTP PC in lungs of premature infants causes
respiratory distress syndrome
37
cholesterol __ CTP PC
cholesterol **inhibits transcription of** CTP PC
38
cholesterol stimulates __, which __ transcription of CTP PC gene
cholesterol stimulates **SRE**, which **inhibits** transcription of CTP PC gene
39
alternative pathways of phosphatidylcholine production can occur in (3)
liver brain mammary glands
40
choline defieicny compromises __ and __ function
choline defieicny compromises **liver** and **kidney** function
41
choline is necessary for __ transport
choline is necessary for **carnitine** transport
42
when is demand for choline extra high?
pregnancy and lactation
43
premenopausal women have __ capacity for synthesis of choline choline prevents __ dysfunction in them | estrogen
premenopausal women have **enhanced** capacity for synthesis of choline choline prevents **developing organ** dysfunction in them
44
ppl with enough folate and B12, but not enough choline had
liver damage and muscle damage
45
choline and brain development
essential! brain extracts choline best during neonatal period (first 4 weeks of life)
46
epigenetics: choline deficiency decreases __ concentrations, resulting in DNA __
epigenetics: choline deficiency decreases **SAM** concentrations, resulting in DNA **hypomethylation**
47
DNA methylation is necessary during __ development for __
DNA methylation is necessary during **fetal** development for **neurogenesis**
48
in adults, choline accelerates the synthesis and release of __ in nerve cells
in adults, choline accelerates the synthesis and release of **acetylcholine** in nerve cells
49
phosphatidylcholine is carried into neurons as part of
apolipoprotein E
50
reduced phosphatidylcholine and choline is associated with __
reduced phosphatidylcholine and choline is associated with **Alzheimer's disease**
51
in mice, choline-rich diet diminished __ loss
in mice, choline-rich diet diminished **memory** loss
52
in rodents, choline (and methyl) deficiency led to __ in the liver which leads to liver __
in rodents, choline (and methyl) deficiency led to **lipid accumulation** in the liver which leads to liver **fibrosis**
53
choline deficiency sensitizes hepatocytes to __ and __ carcinogens
choline deficiency sensitizes hepatocytes to **liver** and **breast** carcinogens

IHN: Biochemistry 2 (38 decks)

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