Erythrocyte Biochemistry

Question 1

What is the first cell in erythropoiesis?

Answer 1

Hemocytoblast (stem cell)

Question 2

After the hemocytoblast, what is the RBC turned into next

Answer 2

A committed cell which contains packed hemoglobin

Question 3

At what phase is the nucleus ejected from the normoblast?

Answer 3

The beginning of phase 3

Question 4

The majority of Hb synthesis is done when

Answer 4

Before the extrusion of the nucleus

Question 5

What is the structure of hemoglobin

Answer 5

A multi-subunit protein (tetramer) made up of:

2 a-globin chains
2 b-globin chains

Each with a molecule of heme in the center

Question 6

What is the carrier of O2 in the heme molecule

Answer 6

Fe

Question 7

Is Heme hydrophobic or hydrophilic

Answer 7

Hydrophobic

Question 8

What three Hb’s are prevalent in the embryonic phase?

Answer 8

Growler 1
Growler 2
Portland

Question 9

What Hb is present in the fetal stage of development

Answer 9

Hb F

This starts at wk. 10

Question 10

What Hb is present in adults

Answer 10

A and A(2)

Question 11

What two genes encode for Hb

Answer 11

16 and 11

Question 12

The F8 histidine is also called what and bound to what?

Answer 12

Also called the proximal histidine and bound to heme

Question 13

The E7 histidine is also called what and what is its function

Answer 13

Also called the distal histidine

It help stabilized the oxygen bound to the heme

Question 14

What type of curve is noted for myoglobin

Answer 14

Hyperbolic curve

Question 15

What type of curve is noted for hemoglobin

Answer 15

Sigmoidal

Question 16

How does oxygen bind to Hb?

Answer 16

In a cooperative manner

This means that the binding of one molecule of oxygen facilitates the binding of the other three

Question 17

Drop of pH allows for what in the Bohr effect

Answer 17

A decrease in the affinity of bound oxygen which allows for a greater release of oxygen into the cells

Question 18

What is the general pathway that iron is absorbed into the liver

Answer 18

Gut lumen - intestinal absorption - plasma transferrin ion - liver

Question 19

Define hereditary hemochromatosis. What is the clinical manifestation

Answer 19

Increased amount of iron in the blood (15g, norm is 3-5)

Presents as organ dysfunction due to iron overload: cirrhosis, arthritis, cardiomyopathy

Question 20

What protein is involved in iron homeostasis

Answer 20

Hepcidin

Question 21

What is the function of hepcidin

Answer 21

Binds to Ferroportin which causes the internalization of Ferroportin

Question 22

When iron is high, what happens

When iron is low what happens

Answer 22

Hepcidin is over expressed, ferroportin levels drop, iron absorption is low

Hepcidin expression is down, ferroportin levels up, iron absorption is high

Question 23

What cofactors influence RBC production

Answer 23

Cobalamin and folic acid

Question 24

Deficiency of B12 and folate can cause what

Answer 24

Megalobastic anemia

This us due to diminishing synthesis of DNA

Question 25

What are the three parts of folate

Answer 25

Pteridine (nitrogen containing ring)
P-amino-benzoic-acid ring (PABA
Glutamate residue chain

Question 26

What is the active form of folate

Answer 26

Tetrahydrofolate (THF)

Question 27

Where is folate absorbed

Answer 27

In the jejunum

Question 28

What happens with a Cobalamin deficiency

Answer 28

Pernicious anemia

This is a megaloblastic macrocytic anemia