Cobalamin or Vitamin B12

Question 1

The most biologically active form of cobalamin

Answer 1

cyanocobalamin

hydroxycobalamin

Question 2

Cobalamin helps in the synthesis of heme.

true or false?

Answer 2

True

Question 3

tissues in the body that contain the highest concentration of B12

Answer 3

kidneys
testes
brain
spleen
pancreas
bone marrow
muscles

Question 4

Cobalamin is absobed with the aid of ___ before it can be absorbed in the ileum

Answer 4

Intrinsic factor IF

Question 5

2 major components of pernicious anemia:

Answer 5

megaloblastic anemia

neurological degeneration

Question 6

Vitamin B12 is a coenzyme for only two mamalian enzymes:

Answer 6

methionine synthase

L-methylmalonyl-coenzyme A mutase

Question 7

Generic descriptor for all cobalamins that exhibit anti-pernicious anemia activity

Answer 7

Cobalamin

Question 8

Deficiency defect from lack of cobalamin

Answer 8

Pernicious anemia

Question 9

Manifestation of pernicious anemia

Answer 9

anorexia
vomiting
diarrhea
achlorhydria
abdominal pain
weight loss
retarded growth

Question 10

Advance cases of pernicious anemia

Answer 10

liver and spleen enlargement
yellowish skin
nerve generation (spinal cord)
paresthesias limbs
difficulty walking

Question 11

characteristics of rbc defect in pernicious anemia

Answer 11

hyperchromic, macrocytic anemia

abnormal size and shape of rbc

Question 12

in pernicious anemia the cells fails to ____ and the total number of cells is ____.

Answer 12

mature

reduced

Question 13

The most biologically active form of cobalamin in the blood

Answer 13

adenylcobamide

Question 14

Cobalamin contains _____-like cobalt-centered ring molecules

Answer 14

porphyrin-like

Question 15

Food Sources

Answer 15

Found in food bound to protein: kidney, milk, eggs, fish, cheese and muscle meats

Question 16

Cobalamin is a Coenzyme of __________

Answer 16

methionine synthase (methylcobalamin)

Question 17

Cobalamin Catalyses the conversion of _______to ________ and regenerates _________

Answer 17

homocysteine
methionine
THF Tetrahydrofuran

Question 18

◦A deficiency of vitamin B12 lowers intracellular levels of ____________, which is required for DNA synthesis.

Answer 18

5,10-methylene-THF

Question 19

cobalamin is important in conversion of _______ to succinyl-CoA

Answer 19

L-methylmalonyl-CoA

Question 20

Cobalamin is An important intermediary in the ______ cycle

Answer 20

tricarboxylic acid

Question 21

Cobalamin requirement _____during pregnancy and lactation

Answer 21

Increased

Question 22

Effects of Deficient Intakes

Answer 22

• Impaired cell division of bone marrow and intestinal mucosa, and RBC
• neurologic abnormalities, ◦numbness, tingling, burning of the feet, stiffness and generalized weakness of the legs

Question 23

megaloblastic anemia is secondary ______ deficiency

Answer 23

folate

Question 24

malabsorption of vit B12 (gastritis to no intrinsic factor (IF); tapeworm)

Answer 24

Pernicious anemia

Question 25

Effects of Excessive Intakes

Answer 25

• Has no appreciable toxicity
• Excess amounts that exceed the limited binding capacity of plasma R are excreted unchanged in the urine and in the feces