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BIBC120 > Final - Lecture 11/12 > Flashcards

Final - Lecture 11/12 Flashcards

1
Q

True or False: B vitamins are often converted to the active forms within the body.

A

True.

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2
Q

Water-soluble vitamins are typically readily excreted in the urine and have small storage pools. What is one exception? Explain.

A

Vitamin B12. It is stored in large quantities in the liver.

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3
Q

About how long does it take to experience clinical symptoms of water-soluble vitamin deficiency?

A

1-8 weeks

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4
Q

What is the structural difference between active and nonactive forms of Vitamin B1?

A

The active form, TPP, contains two phosphates.

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5
Q

What kinds of reactions does Vitamin B1 participate in?

A

Decarboxylation reactions

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6
Q

What is the reactive group in TPP?

A

The thiazole ring.

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7
Q

Decribe the ‘beriberi’ condition.

A

Weak, poorly coordinated, thin, apathetic, loss of short-term memory; results from CNS and GI tract dysfunction along with muscle fatigue (all organs with high energy consumption). May appear in 1-2weeks.

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8
Q

Beriberi is prevalent in individuals whose cultures rely on _____ _____ for ~80% of their calories.

A

Refined grains

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9
Q

How is alcohol associated with Vitamin B1?

A

Alcohol inhibits B1 absorption and promotes B1 excretion.

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10
Q

What behaviors do alcoholics experience when deficient in Vitamin B1/Thiamin?

A

Staggering gait, derangement, eye trouble

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11
Q

What is the structural difference between Vitamin B2 (Riboflavin) and FAD?

A

FAD (active) has an adenine attached to riboflavin (inactive)

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12
Q

How long does it take to develop Vitamin B2 deficiency after initial Vitamin B2 deprivation?

A

2 months.

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13
Q

What are the three clinical symptoms of Vitamin B2 deficiency?

A

(1) Inflammation of the throat, mouth and tongue (glossitis)
(2) Anemia
(3) Fatigue

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14
Q

What is another name for Vitamin B3?

A

Niacin.

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15
Q

What is the structural difference between B3 and NADH?

A

NADH has an ADP attached to the B3.

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16
Q

Coenzyme forms using nicotinamide are oxidized (NAD+) and reduced (NADH). What is the difference in their structures?

A

NAD+ has 3 double bonds in the ring structure with positive charge on the nitrogen. NADH has 2 double bonds in the ring structure and no charge.

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17
Q

How long does it take to develop Vitamin B3 deficiency after initial Vitamin B3 deprivation?

A

2 months.

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18
Q

Some individuals deficient in niacin develop Pellagra. Describe this condition.

A

Broken skin.

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19
Q

What are four clinical symptoms of niacin deficiency?

A

Dementia, delirium, diarrhea, dermatitis, and death.

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20
Q

Corn is rich in niacin, but alone cannot allow for niacin utilization in the human body. Explain why.

A

The niacin in corn is bound by protein, which makes it inaccessible.

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21
Q

Corn is rich in niacin, and with lime water, can allow for niacin to be incorporated to the human diet. Explain why.

A

The CaOH in lime water is alkaline and promotes release of the niacin.

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22
Q

What is the association between niacin and atherosclerosis?

A

Niacin is used as a treatment for artherosclerosis.

Megadoses (1.5-2gm/day) decrease LDL levels and increase HDL levels.

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23
Q

Megadoses (1.5-2gm/day) of niacin can lead to toxicity. What are three of the clinical symptoms of niacin toxicity?

A

(1) flushing, (2) swollen tongue, (3) GI problems, (4) liver damage

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24
Q

Both Vitamin B3 and Vitamin B6 are ______ derivatives.

A

Pyridine.

25
Q

What is another name for Vitamin B6?

A

Pyridoxal.

26
Q

What is the name of the active form of Vitamin B6 and what is the structural difference between the active form and Vitamin B6?

A

Pyridoxal Phosphate (PLP) is the active form. The active form has an additional phosphate group.

27
Q

What is the reactive group of PLP?

A

C=O?

28
Q

What is the name of the reactive intermediate Schiff’s base derived from PLP?

A

The amino acid-PLP Schiff’s base is Aldimine.

29
Q

What are the three components of folic acid?

A

Pteridine, para-aminobenzoic acid, glutamate

30
Q

Red blood cell precursor stem cells require adequate levels of what two vitamins to divide normally?

A

Vitamin B12 and Folate.

31
Q

What is one condition in infants that may result from folate deficiency in the mother?

A

Spina bifida.

32
Q

Describe the Spina bifida condition.

A

Defective growth of the spine, allowing for escape of spinal fluid from the vertebra and pushing outward against the back skin.

33
Q

Vitamin B12 and Folate are both important in promoting the metabolic conversion of homocysteine into what compound? Why is this reaction important for long-term health?

A

Methionine. High homocysteine levels is a risk factor for CVD.

34
Q

What other vitamin also helps to reduce levels of homocysteine in the body? What reaction does it facilitate?

A

Vitamin B6. Homocysteine into Cysteine.

35
Q

What are some clinical effects of high homocysteine levels?

A

Endothelial damage, cholesterol oxidation, platelet aggregation (all ultimately contribute to CVD)

36
Q

Cobalamin-B12 consists of a unique ring structure bound to a metal ion. What are the names of the unique ring structure and the metal ion?

A

Corrin Ring; Cobalt

37
Q

How is pernicious anemia characterized in the elderly?

A

Low red blood cell count and hemoglobin levels, and nerve degeneration (fatal if not treated)

38
Q

What is the cause of pernicious anemia?

A

Autoimmune disorder that destroys gastric parietal cells (which secrete intrinsic factors needed for B12 absorption in the ileum of the small intestine).

39
Q

What is the suggested treatment for B12 deficiency? Why is this also hazardous?

A

Consumption of large quantities of liver or B12 injections. The liver is rich in Vitamin A, and so this practice can result in approaching Vitamin A toxicity levels.

40
Q

What are the major sources of B12?

A

Bacteria are critical in synthesizing B12. Animals get it from intestinal bacteria. Carnivores get it from meat (e.g. humans). Plants do NOT make B12.

41
Q

Large quantities of bacteria capable of synthesizing B12 are known to exist in the colons of humans. Why do humans still require animal sources for B12?

A

The absorption does not occur in the colon, and thus are unable to provide the human host with B12.

42
Q

What percentage of B12 in the body is stored in the liver?

A

50-90%.

43
Q

B12 deficiency is slow to appear in meat-eating humans. Explain.

A

The average meat-eating person has a 2-3 year supply of B12.

44
Q

Ascorbic acid is also known as Vitamin __.

A

Vitamin C.

45
Q

Is Vitamin C the reduced or oxidized form?

A

Vitamin C is the reduced. Dehydroascorbic acid is the oxidized form.

46
Q

Vitamin C is needed for synthesis of what protein? Where is this protein found in the body?

A

Collagen, in connective tissue (for bone, skin, blood vessel and wound healing)

47
Q

What reaction does Vitamin C play a role in?

A

Proline -> hydroxy-proline

48
Q

Hydroxy-proline promotes the formation of what collagen stucture?

A

Collagen triple helix.

49
Q

VItamin C is important as an aqueous free radical trap. Name two cases in the body where Vitamin C fulfills this role.

A

(1) eye (photolysis = free radicals)

2) immune system (ROS and RNS for phagocytosis

50
Q

What are two other functions of Vitamin C?

A

(1) Aids in iron absorption
(2) Synthesis of hormones and neurotransmitters
(3) Regenerates Vitamin E

51
Q

Vitamin C is found in high levels at what locations of the body? Name three.

A

Eye, leucocytes, pituitary gland, adrenal gland, brain

52
Q

What are the relative levels (RDA for M and F, and UL, scurvy, RDA for smokers) for Vitamin C?

A

UL (2g/day)&raquo_space;»» RDA smokers > RDA Male (90mg/day) > RDA Female (70mg/day) > Prevent Scurvy (10+ mg/day)

53
Q

When do Vitamin C deficiency symptoms first appear after initial Vitamin C deprivation?

A

20-40 days.

54
Q

What are the symptoms of Vitamin C deficiency?

A

(1) fatigue
(2) pinpoint hemorrhages in hair folicles
(3) scurvy

55
Q

Describe the ‘scurvy’ condition.

A

loss of collagen synthesis, leads to bleeding gums and joints, slow wound healing

56
Q

What is the take home point against taking multivitamins?

A

If no deficiency, taking more may be harmful.

57
Q

What is the take home point in favor of taking multivitamins?

A

Most individuals in the US are not considered well-nourished: dietary intake recommendations for all vitamins and essential minerals are not met. Multivitamins can fill some of these nutritional gaps effectively.

58
Q

What are two overconsumed nutrients, according to the USDA 2015 Dietary Guidelines Advisory Committee?

A

Sodium, Saturated fat

59
Q

What are three (of five) underconsumed nutrients, according to the USDA 2015 Dietary Guidelines Advisory Committee?

A

Vitamin D, Calcium, Fiber, Potassium, Iron (for women)

BIBC120 (21 decks)

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