Final Review Part 1 Flashcards
Name the functions of Vitamin A (Retinal). (Hint: We discussed 5)
● normal vision
● acts as hormone—affects gene transcription
● proper immune functioning
● structural integrity of epithelial tissue (e.g. skin)
● antioxidant
● other things not covered
Name the enzymes that act on the following: 1) Retinol, 2) Retinal. What products do each of these enzymes make?
1) Retinol dehydrogenase, product is retinal;
2) Retinal dehydrogenase, product is retinoic acid
B-carotene makes 2 of what molecule?
Retinal
Is the starting retinal molecule cis- or trans- before introducing light?
Cis-retinal
Describe how Vitamin A acts as a hormone.
● binds to nuclear receptors
● 9-cis RA binds to retinoid X receptors (RXR)
● 9-cis RA & all-trans RA bind to retinoic acid
receptors (RAR)
Describe Vitamin A’s role in immune responses (there are 2).
● needed for proper immunity in the GI tract
● deficiency can cause impaired gut immunity
and lead to diarrhea
Describe how the structural integrity of epithelial tissue (skin) is affected by lack of Vitamin A.
● deficiency leads to hyperkeratosis
(keratinization of epithelial tissue)
● cornea of eye composed of an outer layer of
epithelial tissue
○ deficiency: cornea gets keratinized → dry and
opaque → blindness
Vitamin A deficiency is the leading cause of blindness in children worldwide. What are some other symptoms of Vitamin A deficiency (there are 2)?
● night blindness
● xerophthalmia (due to insufficient tear
production)
What is the UL for Vitamin A?
3000micrograms/day from animal sources
What are the acute symptoms of Vitamin A toxicity from animal sources (there are 3)?
acute: nausea, headache, dizziness
What are the chronic symptoms of Vitamin A toxicity from animal sources (there are 2)?
chronic: liver damage, hair/bone loss
What are the teratogenic effects of Vitamin A toxicity from animal sources (there are 2)?
birth defects, spontaneous
abortion
True or False: Unlike Vitamin A from animal sources, carotenoids (provitamin A) do not cause
toxicity and have no UL
True.
Where is vitamin A stored?
Fat tissue (beneath skin)
What are the major functions of Vitamin D (there are 4)?
● calcium homeostasis: increases Ca2+
absorption in SI
○ if [Ca2+]blood is low, Ca2+ gets released from bones
● secosteroid hormone
○ cell differentiation in skin, bone, and SI
● supports resistance to infection
● reduces risk of certain cancers (breast,
prostate, colon)
What is the name of the medical condition caused by Vitamin D deficiency?
● Rickets (bones get soft and deformed)
○ also from deficiency of calcium and/or phosphorous
What are the symptoms of Vitamin D toxicity (there are 3)?
● Ca2+ depleted from bones → malformations
● Ca2+ deposited in soft tissues (calcification)
● kidney stones
What are the 2 major functions associated with Vitamin E?
● antioxidant (only vitamin with this sole
function)
● prevents oxidative damage to cell
membranes (resides within lipid membranes)
○ quenches free radicals (ROS)
The active form of Vitamin E is regenerated by which other vitamin?
Vitamin C
Describe the two main risks of Vitamin E deficiency.
● hemolysis, RBC sensitivity due to oxidative
damage → hemolytic anemia
● high risk for smokers, premature infants
exposed to high O2
Name the major symptom of Vitamin E toxicity.
● hemorrhaging
In general, B vitamins are co-factors/co-substrates in energy metabolism. What other general details did they ask us to memorize?
- Fast turnover and small storage pool(except B12)
- Low toxicity
What is the active form of Vitamin B1 (Thiamin)?
Thiamin Pyrophosphate (TPP)
What is the name of the reactive group in Vitamin B1?
Thiazole ring
What kind of reaction would Vitamin B1 typically participate in?
Decarboxylation
The medical condition Beriberi results from Vitamin B1 deficiency. Describe this condition.
weak, poor coordination, thin, apathetic, short term
memory loss
How does alcohol consumption affect Vitamin B1 levels?
alcohol inhibits B1 absorption and stimulates
secretion -> thiamin deficiency -> staggering gait, eye trouble, derangement
Describe the structure of Vitamin B2 (riboflavin).
Ribose, FAD?
What is the active molecule of Vitamin B2 (riboflavin)?
FAD
Deficiency symptoms for Vitamin B2 (riboflavin) appear after 2 months. Describe these symptoms.
inflammation of throat, mouth, tongue(glossitis), anemia, fatigue
What is the active molecule in Vitamin B3 (Niacin)? What type of reactions does it play a role in?
Nicotinamide/NAD+/NADH; Redox reactions
Describe the symptoms of Vitamin B3 (Niacin) deficiency (There are 7).
Pellagra (broken skin), damage to body,
dementia, delirium, diarrhea, dermatitis, death
Vitamin B3 (Niacin) is used as a treatment for what disease? How does it work?
Atherosclerosis; Decreases LDL, increases HDL
Describe the symptoms of Vitamin B3 (Niacin) toxicity.
flushing, swollen tongue, GI, liver damage
In insane asylums, individuals were fed corn, but were also deficient in niacin. Describe an easy solution to this deficiency.
Treat the corn with alkali from lime juice to promote release of niacin from protein binding.
What is the active form of Vitamin B6 (Pyridoxal)?
Pyridoxal phosphate (PLP)
The intermediate form of Vitamin B6 is a Schiff’s base. What is the reactive group in Vitamin B6 (Pyridoxal)?
CHO (Aldehyde)
Describe the symptoms of a Vitamin B6 (pyridoxal) deficiency.
convulsions, and anemia, dermatitis and neural issues
in adults
What kind of enzyme does Vitamin B6 play a role in?
Transaminase
What are the three parts of Vitamin B9 (Folate)?
pteridine + para-aminobenzoic acid + glutamate
What is the active molecule in Vitamin B9 (Folate)?
Tetrahydrofolic acid (THFA)
Describe the symptoms for Vitamin B9 (Folate) deficiency (there are 3).
megaloblastic anemia, spina bifida,
increased homocysteine levels
What is the health issue associated with increased homocysteine levels?
endothelial damage, cholesterol oxidation, platelet aggregation, CVD
Vitamin B12 (Cobalamin) deficiency symptoms include (there are 4):
megaloblastic anemia, nerve degeneration, fatigue, high homocysteine levels (CVD)
Vitamin B12 can be found in animal liver. This is because Vitamin B12 is stored in the liver. How long does this supply typically last after stopping Vitamin B12 intake?
2-3 years.
Vitamin B12 functions in metabolism. Deficiency in Vitamin B12 leads to the medical condition known as:
Pernicious anemia