Flashcards in Final - Lecture 11/12 Deck (59):
True or False: B vitamins are often converted to the active forms within the body.
Water-soluble vitamins are typically readily excreted in the urine and have small storage pools. What is one exception? Explain.
Vitamin B12. It is stored in large quantities in the liver.
About how long does it take to experience clinical symptoms of water-soluble vitamin deficiency?
What is the structural difference between active and nonactive forms of Vitamin B1?
The active form, TPP, contains two phosphates.
What kinds of reactions does Vitamin B1 participate in?
What is the reactive group in TPP?
The thiazole ring.
Decribe the 'beriberi' condition.
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.
Beriberi is prevalent in individuals whose cultures rely on _____ _____ for ~80% of their calories.
How is alcohol associated with Vitamin B1?
Alcohol inhibits B1 absorption and promotes B1 excretion.
What behaviors do alcoholics experience when deficient in Vitamin B1/Thiamin?
Staggering gait, derangement, eye trouble
What is the structural difference between Vitamin B2 (Riboflavin) and FAD?
FAD (active) has an adenine attached to riboflavin (inactive)
How long does it take to develop Vitamin B2 deficiency after initial Vitamin B2 deprivation?
What are the three clinical symptoms of Vitamin B2 deficiency?
(1) Inflammation of the throat, mouth and tongue (glossitis)
What is another name for Vitamin B3?
What is the structural difference between B3 and NADH?
NADH has an ADP attached to the B3.
Coenzyme forms using nicotinamide are oxidized (NAD+) and reduced (NADH). What is the difference in their structures?
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.
How long does it take to develop Vitamin B3 deficiency after initial Vitamin B3 deprivation?
Some individuals deficient in niacin develop Pellagra. Describe this condition.
What are four clinical symptoms of niacin deficiency?
Dementia, delirium, diarrhea, dermatitis, and death.
Corn is rich in niacin, but alone cannot allow for niacin utilization in the human body. Explain why.
The niacin in corn is bound by protein, which makes it inaccessible.
Corn is rich in niacin, and with lime water, can allow for niacin to be incorporated to the human diet. Explain why.
The CaOH in lime water is alkaline and promotes release of the niacin.
What is the association between niacin and atherosclerosis?
Niacin is used as a treatment for artherosclerosis.
Megadoses (1.5-2gm/day) decrease LDL levels and increase HDL levels.
Megadoses (1.5-2gm/day) of niacin can lead to toxicity. What are three of the clinical symptoms of niacin toxicity?
(1) flushing, (2) swollen tongue, (3) GI problems, (4) liver damage
Both Vitamin B3 and Vitamin B6 are ______ derivatives.
What is another name for Vitamin B6?
What is the name of the active form of Vitamin B6 and what is the structural difference between the active form and Vitamin B6?
Pyridoxal Phosphate (PLP) is the active form. The active form has an additional phosphate group.
What is the reactive group of PLP?
What is the name of the reactive intermediate Schiff's base derived from PLP?
The amino acid-PLP Schiff's base is Aldimine.
What are the three components of folic acid?
Pteridine, para-aminobenzoic acid, glutamate
Red blood cell precursor stem cells require adequate levels of what two vitamins to divide normally?
Vitamin B12 and Folate.
What is one condition in infants that may result from folate deficiency in the mother?
Describe the Spina bifida condition.
Defective growth of the spine, allowing for escape of spinal fluid from the vertebra and pushing outward against the back skin.
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?
Methionine. High homocysteine levels is a risk factor for CVD.
What other vitamin also helps to reduce levels of homocysteine in the body? What reaction does it facilitate?
Vitamin B6. Homocysteine into Cysteine.
What are some clinical effects of high homocysteine levels?
Endothelial damage, cholesterol oxidation, platelet aggregation (all ultimately contribute to CVD)
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?
Corrin Ring; Cobalt
How is pernicious anemia characterized in the elderly?
Low red blood cell count and hemoglobin levels, and nerve degeneration (fatal if not treated)
What is the cause of pernicious anemia?
Autoimmune disorder that destroys gastric parietal cells (which secrete intrinsic factors needed for B12 absorption in the ileum of the small intestine).
What is the suggested treatment for B12 deficiency? Why is this also hazardous?
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.
What are the major sources of B12?
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.
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?
The absorption does not occur in the colon, and thus are unable to provide the human host with B12.
What percentage of B12 in the body is stored in the liver?
B12 deficiency is slow to appear in meat-eating humans. Explain.
The average meat-eating person has a 2-3 year supply of B12.
Ascorbic acid is also known as Vitamin __.
Is Vitamin C the reduced or oxidized form?
Vitamin C is the reduced. Dehydroascorbic acid is the oxidized form.
Vitamin C is needed for synthesis of what protein? Where is this protein found in the body?
Collagen, in connective tissue (for bone, skin, blood vessel and wound healing)
What reaction does Vitamin C play a role in?
Proline -> hydroxy-proline
Hydroxy-proline promotes the formation of what collagen stucture?
Collagen triple helix.
VItamin C is important as an aqueous free radical trap. Name two cases in the body where Vitamin C fulfills this role.
(1) eye (photolysis = free radicals)
(2) immune system (ROS and RNS for phagocytosis)
What are two other functions of Vitamin C?
(1) Aids in iron absorption
(2) Synthesis of hormones and neurotransmitters
(3) Regenerates Vitamin E
Vitamin C is found in high levels at what locations of the body? Name three.
Eye, leucocytes, pituitary gland, adrenal gland, brain
What are the relative levels (RDA for M and F, and UL, scurvy, RDA for smokers) for Vitamin C?
UL (2g/day) >>>>>> RDA smokers > RDA Male (90mg/day) > RDA Female (70mg/day) > Prevent Scurvy (10+ mg/day)
When do Vitamin C deficiency symptoms first appear after initial Vitamin C deprivation?
What are the symptoms of Vitamin C deficiency?
(2) pinpoint hemorrhages in hair folicles
Describe the 'scurvy' condition.
loss of collagen synthesis, leads to bleeding gums and joints, slow wound healing
What is the take home point against taking multivitamins?
If no deficiency, taking more may be harmful.
What is the take home point in favor of taking multivitamins?
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.
What are two overconsumed nutrients, according to the USDA 2015 Dietary Guidelines Advisory Committee?
Sodium, Saturated fat