Nutrition- Vitamin B12

Front 1

What is another name for Vitamin B12?

Back 1

Cobalamin

Front 2

What is the last vitamin to be found?

Back 2

Vitamin B12

Front 3

What was Vitamin B12 originally identified as?

Back 3

Anti-pernicious anemia factor in liver.

Front 4

What is Vitamin B12?

Back 4

Generic descriptor for all corrinoids (compounds containing the corrin nucleus) exhibiting qualitatively the biological activity of cannobalamin.

Front 5

What is Vitamin B12 made up of?

Back 5

Macrocytic ring made up of four reduced pyrrole (5-membered aromatic heterocylce rings) linked together.

An atom of Co+ i found in the center of the ring, and attached to it is the nucleotide 5,6-dimethylbenzimadzole.

Front 6

What is Vitamin B12 stable in?

Back 6

Stable and resistant to light, heat, oxidaiton.

Front 7

How is cobalamin found in foods?

Back 7

Linked to proteins/peptides

Front 8

Does cobalamin need to be digested prior to absorption?

Back 8

Yeah. It needs to be released from the proteins attached to it.

Front 9

How is cobalamin digested?

Back 9

Gastric proteolytic enzyme pepsin and hydrochloric acid in the stomach.

Front 10

Where is cobalamin digested?

Back 10

In the stomach

Front 11

What inside the body will want to utilize cobalamin?

Back 11

Bacteria

Front 12

How is Cobalamin protected from bacteria

Back 12

Cobalamin is binded to protein R present in saliva and gastric juice- making a B12:R complex

Front 13

When is cobalamin released from protein R?

Back 13

In the alkaline environment of the small intesintine

Front 14

How is cobalamin released from protein R?

Back 14

By pancreatic proteases

Front 15

What are all forms of cobalamin bound to?

Back 15

Intrinsic factor (IF),

Front 16

What is IF?

Back 16

A glycoprotein that is made up of parietal cells in the stomach but escapes enzymatic catabolism from the stomach and binds to cobalamin in the small intestine after it is released from R proteins.

Front 17

What happens to humans lacking IF?

Back 17

They have very low ability to absorb Vitamin B12 and excrete 100% of the Vitamin B12 in the feces, as apposed to 30-60% of fecal excretion in persons with adequate IF.

Front 18

What does Vitamin B12 and IF make?

Back 18

Vitamin B12:IF complex

Front 19

Where does the B12-IF complex go to once bound together?

Back 19

Travels to the ileum where it interacts with IF receptor (Cubulin)

Front 20

What is IF receptor called?

Back 20

Cubulin

Front 21

What happens when Vitamin B12-IF complex interacts with cubulin

Where does this occur?

Back 21

Triggers active endocytic internalization of the complex into the enterocyte

Distal third of the ileum.

Front 22

What happens once the B12:IF complex is inside the enterocyte

Back 22

Vitamin B12 and IF dissociate and then Vitamin B12 binds to transcobalamin 2 (TC2) for transport in the blood.

Front 23

How does Cobalamin enter from blood into cell?

Back 23

The cellular uptake of vitamin b12 is mediated by the TC2 receptor that is ubiquitously expressed.

The TC2-B12 complex enters the cell by endocytosis.

Front 24

What happens to the TC2-B12 complex once inside the cell?

Back 24

Proteolytic degradation of TC2 and release of Vitamin B12 within the cytosol.

Front 25

How long can Vitamin B12 be stored?

How does this differ from other water-soluble vitamins?

Back 25

It can be stored and retained in the body for years

Front 26

How long does it take for signs of cobalamin deficiency to manifest?

Back 26

3-5 years, because it can stay in the cell for years.

Front 27

Where is most of the cobalamin found?

Back 27

Liver- 50% of the total cobalamin in the body.

Front 28

What other tissues contain cobalamin but in smaller amounts?

Back 28

Muscle, bone, heart, kidneys, brain, spleen

Front 29

What does Vitamin B12 help with?

Back 29

It is part of enzymes that help in the metabolism of propionate, amino acids, and single carbon.

Front 30

What are the two forms of Vitamin B12 required in two enzymatic reactions?

Back 30

Methylcobalamine and Adenosylcobalamin

Front 31

What is methylcobalamine used in?

Back 31

Used as a coenzyme in the conversion of homocystiene into methionine

Front 32

What is adnosylcobalamin used in?

Back 32

Conversion of methylmanlonyl-CoA to succinyl-CoA in the mitochondria of cells- important in the process of synthesis and degradation of amino acids (e.g leucine) and proprionate.

Front 33

What happens if you do not have vitamin b12?

Back 33

Active folate coenzymes cannot be formed and this impairs DNA synthesis as well as cell differentiation and maturation.

There is a delay in cell division and arrested DNA synthesis leading to teh formation of enlarged cells (megaloblastic anemia)

Front 34

Why was megaloblastic anemia originally named pernicious anemia?

Back 34

Due to its fatal prognostic prior to the discovery that vitamin b12 cold cure the condition`

Front 35

What else happens in vitamin b12 defficient people?

Back 35

Neurological abnormalities, progressive nerve demyleination

Front 36

Do vegetables and fruit have vitamin b12

Back 36

No

Front 37

can vegetarians get vitamin b12 easily?

Back 37

No- because no vitamin b12 in fruits/veg

Front 38

What do vegetarians have to do for vitamin b12

Back 38

they need supplementation to meet the RDA

Front 39

do you need to have an RDA of cobalt since it is part of this vitamin b12? Why not?

Back 39

no you do not.

This is b/c vitamin B12 cannot be synthesized from dietary cobalt. In fact, it is the vitamin B12 content of foods and the diet, rather than cobalt itselt that is important in human nutrition.

Front 40

Primary Functions of vitamin B12?

Back 40

Assists with the formation of blood, it is required for healthy nervous system function, and it is invovled in the metabolism of homocysteine.

Front 41

Symptoms of Vitamin B12 deficiency?

Back 41

Pernicious anemia, tingling and numbness of extremities, nerve damage, memory loss, disorientation, and dementia.

Front 42

Symptoms of Vitamin b12 tocicity?

Back 42

None known.