Brainscape's Knowledge GenomeTM

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


See full index

Biochem Quiz 4 Winter > Vitamins > Flashcards

Vitamins Flashcards

1
Q

WATER-SOLUBLE VITAMINS

General features

  • Most water-soluble vitamins are precursors of coenzymes involved in intermediary metabolism.
  • All water-soluble vitamins except for vitamin B12 are present in vegetables.
  • Deficiency of all water-soluble vitamins except for vitamin B12 produces clinical symptoms within weeks due to low body stores.
A

WATER-SOLUBLE VITAMINS

General features

  • Most water-soluble vitamins are precursors of coenzymes involved in intermediary metabolism.
  • All water-soluble vitamins except for vitamin B12 are present in vegetables.
  • Deficiency of all water-soluble vitamins except for vitamin B12 produces clinical symptoms within weeks due to low body stores.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What enzymes is Thiamine (B1) pyrophosphate a coenzyme to?

A
  • pyruvate dehydrogenase
  • α-ketoglutarate dehydrogenase
  • transketolase
  • (All carb metabolism)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What does a deficiency in Thiamine cause?

A
  • Korsakoff’s syndrome in alcohol abusers.

* Beriberi- peripheral neuropathy and dilated cardiomyopathy.

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

What are the requirements of administering Thiamine to alcoholic patients?

A

• always administer Thiamine with glucose to alcohol abusers.

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

What is B2 Riboflavin are precursor to?

A
  • flavin mononucleotide (FMN)

* flavin adenine dinucleotide (FAD).

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

What deficiency of B2 Riboflavin causes what?

A
  • fissuring at the angles of the mouth
  • dermatitis
  • purple tongue.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is B3 Niacin? What is it a precursor for? Why is it not an vitamin, strictly speakin?

A
  • Both nicotinamide or nicotinic acid.
  • Precursors of nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) coenzymes.
  • We can synthesize niacin from tryptophan.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does a Niacin deficiency cause?

A

• pellagra (Italian for “sour skin”)- dermatitis, diarrhea, dementia, and death.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is Hartnup Disease? What is Carcinoid Syndrome?

A
  • Hartnup is diminished tryptophan uptake
  • Carcinoid syndrome is altered tryptophan metabolism
  • Both can result in Niacin B3 deficiencies.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is Niacin B3 used therapeutically?

A

• Lower LDL and VLDL cholesterol in type IIb hyperlipoproteinemia.

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

What is Pantothenic Acid B5? Are there deficiencies?

A
  • Component of coenzyme A

* Widely distributed in food; deficiency syndrome has not been characterized.

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

What is B6? What is B6 a precursor for?

A
  • Collective term for pyridoxine, pyridoxal, and pyridoxamine.
  • Precursors of pyridoxal phosphate, a coenzyme catalyzing reactions involving amino acids.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why is B6 prescribed together with isoniazid (a tuberculosis drug). What are the symptoms of B6 deficiency?

A
  • B6 binds to isoniazid
  • prevent functional deficiency
  • seizures.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does Biotin B7 function in the body?

A
  • A coenzyme in carboxylation reactions

* covalently bound to lysine residues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the symptoms of Biotin deficiency?

A
  • Dermatitis
  • Glossitis
  • nausea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What dietary practice causes biotin Deficiency?

A
  • eating >20 raw eggs per day

* biotin-binding protein avidin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How is Folate B9 used in the body?

A

• For one-carbon metabolism, including purine and thymidine (DNA) synthesis.

18
Q

What does a deficiency in Folate B9 cause? What efforts have been made to prevent deficiency?

A
  • megaloblastic anemia in adults
  • neural tube defects in fetuses.
  • Given during 1st trimester of pregnancy
  • Supplemented in “enriched” foods since 1998.
19
Q

What is Cobalamin B12 a precursor to?

A
  • methylcobalamin, needed to synthesize methionine from homocysteine in blood cells
  • deoxyadenosylcobalamin, needed for fatty acid metabolism in brain cells.
20
Q

What factor is needed to absorb B12?

A
  • Not produced by plants.

* Requires intrinsic factor for intestinal absorption.

21
Q

When is B12 deficiency common?

A
  • Vegans

* patients with pernicious anemia (lacking intrinsic factor).

22
Q

What does Cobalamin B12 deficiency cause?

A
  • megaloblastic anemia by functionally trapping folate
  • subacute combined degeneration of the spinal cord
  • dementia.
23
Q

What is the Etiology of megaloblastic anemia in vitamin B12 deficiency?

A
  • the folate trap hypothesis
  • During methionine synthesis, N5-methyl-tetrahydrofolate transfers a methyl group to vitamin B12 to form methylcobalamin.
  • This reaction is also required to metabolize N5-methyl-tetrahydrofolate.
  • Lack of vitamin B12 blocks the metabolism of N5-methyl-tetrahydrofolate, which now cannot be used for DNA synthesis.Clinical symptoms become manifest only after years of deficiency due to large body stores.
24
Q

What is the treatment for pernicious anemia?

A
  • intramuscular B12 injections

* circumvents intrinsic factor

25
Q

What is treatment of megablastic anemia?

A

• Folate supplementation ameliorates deficiencies of either vitamin B12 or folate.

26
Q

Does folate supplementaiont treat subacute combined degeneration of the spinal cord caused by vitamin B12 deficiency?

A

No

27
Q

What is Ascorbic Acid Vit C necessary for?

A

• post-translational hydroxylation of proline, especially in collagen.

28
Q

What do deficencies of Vit C cause?

A
  • scurvy- bleeding gums
  • Hemorrhages around corkscrew hair follicles
  • bone pain caused by bleeding underneath periosteum
  • poor wound healing
29
Q

What do mega-doses of Vit C cause?

A

• oxalic acid kidney stones.

30
Q

FAT-SOLUBLE VITAMINS

General features

• In the United States, deficiencies of fat-soluble vitamins are often present in patients with fat malabsorption syndromes.

  • Fat-soluble vitamins are stored in the body and metabolized slowly, and therefore deficiency usually develops only after months of inadequate intake.
  • Excess consumption of either vitamin A or D leads to toxicity.
A

FAT-SOLUBLE VITAMINS

General features

• In the United States, deficiencies of fat-soluble vitamins are often present in patients with fat malabsorption syndromes.

  • Fat-soluble vitamins are stored in the body and metabolized slowly, and therefore deficiency usually develops only after months of inadequate intake.
  • Excess consumption of either vitamin A or D leads to toxicity.
31
Q

Vitamin A

  • Collective term for retinol, retinal, the essential visual pigment, and retinoic acid, which is necessary to maintain differentiation of epithelial cells.
  • Vitamin A can be obtained from animal sources or derived from β-carotene present in plants.

• Deficiency causes 1.2 million cases of permanent blindness each year in the developing world. First symptom is night blindness, which can be rapidly improved with emergency vitamin A therapy.

A

Vitamin A

  • Collective term for retinol, retinal, the essential visual pigment, and retinoic acid, which is necessary to maintain differentiation of epithelial cells.
  • Vitamin A can be obtained from animal sources or derived from β-carotene present in plants.

• Deficiency causes 1.2 million cases of permanent blindness each year in the developing world. First symptom is night blindness, which can be rapidly improved with emergency vitamin A therapy.

32
Q

What are important physical signs of vitamin A deficiency?

A
  • corneal epithelial cell dedifferentiation/keratinization

* xeropthalmia and Bitot’s spots.

33
Q

What is vitamin A used to treat?

A

• Used in treatment of acne and psoriasis

34
Q

What can overuse of vitamin A cause?

A
  • skin rash, liver damage, and raised intracranial pressure

* teratogenic: avoid giving to pregnant patients

35
Q

Vitamin D

• Vitamin D can be produced endogenously in the skin by uv irradiation, or obtained from either animal or plant tissues.

A

Vitamin D

• Vitamin D can be produced endogenously in the skin by uv irradiation, or obtained from either animal or plant tissues.

36
Q

What is the active form of Vitamin D? What is its function with regards to Calcium?

A
  • Calcitriol
  • Formed by two successive hydroxylation reactions: first in the liver, and subsequently in kidney, bone, or placenta.
  • Calcitriol is a steroid hormone that increases calcium absorption by the intestine epithelium.
  • In the United states, milk is fortified with vitamin D.
37
Q

What do deficiencies in Vitamin D cause?

A
  • demineralization of formed bone: osteomalacia (bone pain, microfractures and compression fractures)
  • failure to mineralize developing bones in children, leading to rickets (bowed legs).
38
Q

What are risk factors for Vit D deficiency? What is treatment? What are possible side effects of treatment?

A
  • Risk factors for deficiency = lack of milk consumption (often due to lactose intolerance), dark skin color, low sun exposure.
  • Calcitriol is given as therapy, but often causes hypercalcaemia: “bones, stones, and abdominal moans.”
39
Q

What is Tocopherol Vitamin E? What do deficiencies cause?

A
  • Antioxidant that protects lipid membranes.

* Deficiency can cause red blood cell fragility.

40
Q

What is Vitamin K used for? Where is it endogenously produced?

A
  • post-translational carboxylation of glutamate, which is required for calcium binding by several blood clotting factors, including prothrombin.
  • Produced by intestinal bacteria.
41
Q

What do Vitamin K deficiencies cause?

A
  • hemorrhage with a long prothrombin time (PT)

* Decreased clotting

42
Q

Under what clinical circumstances is vitamin K administered to patients? When is Vit K intentionally blocked as a medicine?

A
  • premature infants, who lack the intestinal bacteria that provide vitamin K
  • adults on long-term antibiotic therapy.
  • Vitamin K action is intentionally blocked by the drug coumarin, a vitamin K antagonist, to prevent clotting (e.g. in patients with prosthetic heart valves).

Biochem Quiz 4 Winter (6 decks)

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