Chapter 28 Micronutrients: Vit B9 and B12

Question 1

Overview:

1. Chemically unrelated organic compounds that cannot be synthesized in humans and must be supplied in the diet.
2. Two classifications of vitamins ?
3. which type of class of vitamins can be readily excreted in urine with rare toxicity ?
4. which class of vitamins are released, absorbed and transported by chylomicrons ?
5. class of vitamins stored in the liver and adipose tissue ?
6. which class of vitamins are usually precursors of coenzymes for the enzymes of intermediates of metabolism
7. The only fat soluble vitamin has a coenzyme function ?

Answer 1

1. vitamins
2. water soluble and fat soluble
3. water soluble vitamins
4. fat soluble vitamins ( A , D, E, K )
5. A D E K
6. water solubles ( B’s)
7. vitamin K

Question 2

B complex Energy Releasing Vitamins

Answer 2

1. B1 — THIAMINE
2. B2 —RIBOFLAVIN
3. B3 —NIACIN
4. B5– PANTHANOIC ACIC
5. B7 – BIOTIN

Question 3

HEMATOPOIETIC B COMPLEX VITAMINS

Answer 3

1. B 9 – FOLATE
2. B 12 – COBALAMINE

Question 4

FOLIC ACID VITAMIN B9

1. Traits: what is folic acid feature trait in chemistry ?
2. what types of demographics does the deficiency show up ?
3. where can we obtain folic acid ?

Function

1. what is the reduced (active) form of folic acid ?
2. which amino acids do THF receive one-carbon fragments from ?
3. where do THF transfer the carbon accepted to ?

Answer 4

Folic Acid Vit B9

1. transfer of one-carbon metabolism
2. pregnant women and alcoholics
3. leafy dark greens

Function

1. THF
2. serine, glycine and histidine
3. pyrimidine nucleotide (incorporated into DNA)

Question 5

Continue Folic Acid THF B9 : Nutritional Anemias

1. Define what nutritional anemia is, in the sense of B9 deficiency ?
2. what are the two kinds anemia involved with deficient THF ?
3. what type of anemia is with MCV below normal ?
4. cause of MCV below normal ?
5. type of anemia with MCV higher than normal ?
6. cause of MCV higher than normal ?
7. Macrocytic anemias can also be classified as ?
8. Deficiency of hemopoietic B complex causes the accumulation of ?

Folate and anemia

1. conditions in which there is increased demand of the nutrient ?
2. causes of poor absorption ?
3. primary result of folic acid deficiency ?

Answer 5

Continue Folic Acid THF B9 : Nutritional Anemias

1. caused by inadequate intake of one or more essential nutrients- these anemias can be determined/classified by the size and/volume of RBCs
2. Microcytic anemia and macrocytic
3. microcytic anemia
4. lack of iron
5. Macrocytic anemia
6. lack of B12 or B9
7. Megaloblastic anemia
8. immature RBC precursors

Folate and Anemia

1. pregnancy and lactation
2. alcoholism and damage of the small intestine
3. megaloblastic anemia (macrocytic anemia)

Question 6

Folate and Neural Tube Defects

1. most common neural tube defects ?

Answer 6

1. Spina Bifida and anencephaly (NTD)

Question 7

COBALAMIN Vitamin B12

1. Two enzymatic reactions that require vitamin B12 ?
2. Remethylation and isomerization happens during the degradation of which A.A. ?
3. enzymatic reactions happen as well in the degradation of what type of Fatty acids ?
4. what happens to Odd chain FA when cobalamin is deficient ?
5. example of Systems that can be harmed by Odd chain FA accumulation ?

Distribution of B12

1. where is B12 made (synthesized)
2. Preformed Vitamin is found where ?
3. Cobalamin is present in what types food ?

Folate Trap Hypothesis

1. B12 deficiency is most found in which part of the body (most pronounced in?)
2. tissues in the bone marrow and small intestines require important nutrients that help for the formation of nucleotides in regard to DNA replication (very important for DNA replication) ?
3. Folate trap: what does it mean ?
4. Cobalmin B12 deficiency leads the deficiency of the efficient forms of what nutrient ?
5. very low B12 causes what type of anemia ?

Answer 7

COBALAMIN Vitamin B12

1. remethylation of homocystein to methionine and isomerization methylmalonyl CoA.
2. isoleucine,Valine, threonine and methionine
3. Odd chain FA
4. accumulate (build up) and incorporate into cell membranes
5. CNS

Distribution of B12

1. microorganisms (only by microorganisms) not found in plants
2. Animals ( in their intestinal microbiota)
3. meat, fish, eggs, dairy , and fortified cereals

Folate Trap Hypothesis

1. bone marrow and intestines
2. N⁵N¹⁰ Methylene and N¹⁰- formyl groups of THF (B9)
3. In B12 deficiency; using N⁵-THF in methylation to Hcy is impaired (Folate is pretty much trapped in the N⁵- THF form and therefore cannot be converted ( so this form accumulates in the blood) causing problems
4. THF forms needed in purine and TMP synthesis
5. Megaloblastic anemia

Question 8

Clinical Indications of Cobalamin

1. how much B12 is usually stored in the body ?
2. how can B12 deficiency be checked ?
3. decreased intake of vitamin B12 symptoms show up when ?
4. when B12 absorption is impaired, how long until signs show ?
5. what is pernicious anemia ?

Cobalamin Pathway

10 steps

Pernicious Anemia

1. What happens in pernicious anemia what is severely not absorbed ?
2. Pernicious anemia is a type of autoimmune disease; destruction of which part of the GI is impaired ?
3. Lack of INTRINSIC FACTOR prevents the absorption of what vitamin ?

Answer 8

Clinical Indications of Cobalamin

1. 2 - 5 mg
2. levels of methyl malonic acid
3. several years until symptoms show
4. months (faster rather than just showing up after years)
5. failure to absorb the vitamin cobalamin

Cobalamin Pathway

1. B12 released from food in acidic environment of the stomach
2. Free B12 binds to Glycoprotein ( R-protein/ haptocorrin)
3. Free B12-Haptocorrin complex moves into small intestines
4. B12 is released from the complex ( by pancreatic enzymes)
5. B12 now binds to INSTRINSIC FACTOR (IF) another protein
6. IF-B12 complex travels to intestines and binds to cubulin (surface of mucosal cells)
7. B12 is absorbed into circulation by (transcobalamin)
8. B12 is then stored in the liver
9. Released INTO bile
10. reabsorbed in the ILEUM

Pernicious Anemia

1. cobalamin (severe malabsorption of B12)
2. Gastric parietal cells ( responsible for making IF)
3. B12 Cobalamin