Lecture 9 & 10 - Hemoglobin I & II

Question 1

Two components necessary for Hb production

Answer 1

Vit. B6 and Iron

Question 2

Two things necessary for DNA synthesis

Answer 2

Vit. B12 and Folic acid

Question 3

Lack organelles, biconcave (utilizing spectrin), anucleated.

Answer 3

Mature red blood cells

Question 4

Explain why the biconcave shape is important for RBCs

Answer 4

Through spectrin, the plasma membrane of RBCs have a high ability to deform. This is important because the diameter of capillaries are often smaller that the diameter of RBCs.

Question 5

Transferrin f(x)

Answer 5

“Salvage” iron from damaged/lysed blood cells

Question 6

F(x) of haptiglobin

Answer 6

Salvage Hb and excrete in bilirubin (prevents free heme from causing oxidative stress to the body)

Question 7

Each hemoglobin chain is comprised of ____ alpha-domains.

Answer 7

8

Question 8

Acts to bind oxygen in the Hb molecule

Answer 8

Proximal (or “E7”) Histidine

Question 9

Binds to Iron in Hb molecule

Answer 9

Distal (or “F8”) Histidine

Question 10

Vast majority of adult hemoglobin

Answer 10

Hemoglobin-Alpha

Question 11

Small % of adult hemoglobin

Answer 11

Hb-A2

Question 12

Structure of Hb-A

Answer 12

2 alpha subunits; 2 beta subunits

Question 13

Structure of Hb-A2

Answer 13

2 alpha subunits; 2 delta subunits

Question 14

Structure of fetal hemoglobin (Hb-F)

Answer 14

2 alpha subunits; 2 gamma subunits

Question 15

Number of Fe2+ per Hb subunit.

Answer 15

1 (total of 4 in the complete Hb molecule)

Question 16

Domains of Hb that form the “pocket” for Fe

Answer 16

EFG

Question 17

What oxidative state does iron take in Hb?

Answer 17

Fe2+

Question 18

Binds to oxygen and results in a “barrier” to formation of carboxy-Hb

Answer 18

Distal histidine (E7)

Question 19

The Bohr Effect promotes oxygen release in tissues by what mechanism?

Answer 19

Allosteric effect of incr. [H+] and incr. [CO2]

Question 20

Binding of oxygen to Hb is under _____ control.

Answer 20

allosteric

Question 21

This type of control deals with a molecule binding other than at an enzyme/protein active site to change a conformation.

Answer 21

What is “allosteric?”

Question 22

Iron exists in the ____ state to prevent generation of free radicals.

Answer 22

2+

Question 23

What is meant by “Hemoglobin is cooperative?”

Answer 23

The binding of one molecule to a Hb subunit causes a conformational in the other subunits.

Question 24

Compare/contrast Hb and Mb

Answer 24

Question 25

What molecules inhibit oxygen binding to Fe2+?

Answer 25

Hydrogen ions 2,3-BPG CO2

Question 26

What is the mechanism behind the offloading of oxygen as a result of increased hydrogen ion []? (In regard to O2-Hb dissociation curve)

Answer 26

Increased [H+] results in a right shift of the oxygen-Hb dissociation curve; this is due to oxygen having less affinity for Hb in acidic environments (actively metabolizing tissue)

Question 27

What is the mechanism behind the right shift of the oxygen-Hb dissociation curve in increased [CO2] levels?

Answer 27

Increased CO2 levels are found in actively metabolizing tissues. As a result, increased CO2 produces a rightward shift of Oxygen-Hb curve, which means that the oxygen dissociates ("offloads") freely from Hb in high [CO2]

Question 28

This molecule maintains the Hb in the T-state, preventing any binding of Oxygen to Hb

Answer 28

2,3-BPG (allows more oxygen offloading)

Question 29

3 molecules producing a right shift of the oxygen-Hb dissociation curve

Answer 29

Increased: H+ CO2 2,3-BPG