Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

nutr 3330 midterm > Vitamin C > Flashcards

Vitamin C Flashcards

1
Q

what is another term for Vit C

A

ascorbic acid or ascorbate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

is Vit C essential

A

not in all species

humans are one of few species that CANNOT synthesize Vit C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the two forms that Vit C can exist in? can this reaction go both ways?

A

ascorbic acid (reduced) and dehydroascorbate (oxidized)

yes, it is reversible and can exist in either state and can go back and fourth between states

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

**what is Vit C synthesized from?

A

glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

**what is the one enzyme humans are missing for Vit C synthesis

A

gulonolactone oxidase

*KNOW THIS ENZYME

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

why do we not have the enzyme for Vit C synthesis

A

we have the gene for it, but the gene is mutated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

gulonolactone oxidase is needed to convert ______ to _______ and ultimately, glucose to Vit C

A

gulonolactone
to
ketogulonolactone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Vit C metabolic role

A
  • HYDROXYLASE REACTIONS are the calling card for Vit C
  • ascorbic acid DONATES HYDROGENS and becomes dehydroascorbic acid
  • ascorbic acid is a REDUCING AGENT
  • keeps compounds in their reduced state
  • vit C itself is not helping the metabolic role, it more the behind the scenes stuff
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

summarize the metabolic role of Vit c

A

1) collagen formation
2) carnitine synthesis
3) tyrosine metabolism (catabolism, synthesis of neurotransmitters)
4) antioxidant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the best characterized role of Vit C

A

collagen synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

collagen synthesis and Vit c

A
  • collagen is largest protein in body
  • needs to be hydroxylated;cross linking
  • proline and lysine residues hydroxylated
    • prolyl/lysyl hydroxylase
    • also needs IRON as a cofactor
    • iron must be in its reduced state

-ascorbate keeps iron in reduced state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

vit C and carnitine synthesis

A
  • carnitine needed to transport FA into mitochondria (FA is stored energy so needs to go to mitochondria)
  • synthesized from lysine and methionine
  • two inron-dependent hydroxylase enzymes
  • ascorbate keeps iron in reduced state
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Vit C and tyrosine metabolism

A

-tyrosine–>dopamine–>norepinephrine

  • needs beta hydroxylase, as well as copper
  • ascorbate keeps copper in reduced state

in order for tyrosine to be a precursor for neurotransmitters, it needs a reduced mineral to act as cofactor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Vit C as an antioxidant

A

direct antioxidant production

  • powerful reducing agent
  • neutralizes free radicals and other oxidant species

indirect antioxidant protection

  • helping to regenerate Vit E
  • supply electrons to regenerate active reduced form of other biological antioxidants
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Vit C, nutrient interactions

A

IRON
-enhances absorption of non-heme iron

COPPER
-inhibits copper absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

**how does Vit C enhance absorption of non heme iron

A

non heme source of iron is not very bioavailable

Vit C helps by:

1) reduced iron to ferrous from ferric
2) forms soluble complex with iron
3) facilitates incorporation into ferritin

17
Q

Vit C food sources

A
  • fruits and veggies!
  • organ meats
  • dramatically reduces during storage
  • highly susceptible to oxidation

-loss of Vit C from food is quite high

18
Q

Vit C deficiency

A

-scurvy (long term deficiency)…could be prevented by addition of limes lemons and oranges

19
Q

scurvy symptoms

A
  • extreme fatigue
  • impaired wound healing
  • hemorrhage in skin, mucous membranes and muscles
  • weakness of collagenous structures
  • depression
  • edema
20
Q

Common cold and Vit C

A
  • minimizes inflammatory effects of oxidized products in healthy individuals
  • decreases severity of cold
21
Q

cataracts and vit C

A

-vit C concentrated in eye

22
Q

Vit C and cancer

A
  • oral cavity, pharynx, edophagus, stomach
  • fruits veggie intake protective
  • role in immunocompetence
  • free radical scavenger
23
Q

CVD and Vit C

A

neutralize oxidized LDL’s

24
Q

is Vit C toxic

A

no, its very non toxic, UL is 22x the RDA

25
Q

what are susceptible Vit C toxicity populations

A

oxalate kidney stones

  • oxalate is a metabolite of Vit C
  • excreted by kidney
  • can combine with Ca

Iron metabolism problems

  • vit C enhances iron absorption
  • hemochromatosis

nutr 3330 midterm (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions