hemoglobin structure and function

Question 1

A heme prosthetic group consists of iron bound to a ________ ring.

Answer 1

protoporphyrin.

Question 2

Each red blood cell in the body contains approximately _______ molecules of hgb.

Answer 2

280 million

Question 3

When 0 zero O2 molecules are bound to hemoglobin, it is said to be in what configuration

Answer 3

T or taut

Question 4

The T configuration is caused by lack of O2 binding which alters ______ within hemoglobin

Answer 4

inter- and intra- salt bonds within the molecule.

Question 5

Define P50

Answer 5

the partial pressure of oxygen at which the O2 carrying protein in 50% saturated.

Question 6

Hemoglobin in a tetramer whereas myglobin is a ______

Answer 6

monomer.

Question 7

the basic shape of the hemoglobin O2 dissociation curve follows what values for % saturation at the following partial pressures?:

10-
30-
40-
60-

Answer 7

10-10
30-60
60-90
40-75

Question 8

What can shift the O2 dissociation curve to the left?

Answer 8

decreased BPG/DPG
decreased acidity (increased pH)
decreased temp.

Question 9

What can shift the O2 dissociation curve to the right?

Answer 9

increased BPG/DPG
increased acidity (decreased pH)
increased temp.

Question 10

How will a rightward shift affect O2 affinity?

Answer 10

decrease affinity

Question 11

How will a leftward shift affect O2 affinity?

Answer 11

increase affinity

Question 12

Describe the Bohr effect

Answer 12

CO2 produced by tissues in metabolism is converted to bicarb and H+ by carbonic anhydrase. This leads to a drop in pH (increase in acidity) which shifts the O2 curve to the right, decreasing O2 affinity and allowing the tissues to more readily receive O2. technically any shift due to pH is known as the Bohr effect.

Question 13

How can we rationalize the O2 curve shift as a result of change in temperature?

Answer 13

With exercise or fever (increase in temp) metabolism is higher and the need for O2 greater. Thus, an increase in temp. will shift the curve to the right and decrease O2 affinity for hgb, allowing O2 to be unloaded into the tissues more readily.

Question 14

How is BPG created in the body?

Answer 14

It is a byproduct of anaerobic metabolism. Thus, increasing amounts of BPG suggest the need for more O2. BPG decreases O2 affinity for hgb and allows O2 to be more readily picked up by the tissues.

Question 15

Alpha-like genes (for hgb) are on what chromosome? what about Beta-like genes?

Answer 15

alpha- chromosome 11

Beta- chromosome 16

Question 16

What are the 3 distinct hemoglobins present in embryos (week 4-14 only)?

Answer 16

Hemoglobin Gower I- (zeta2 epsilon2)
Hemoglobin Gower II- (alpha2 epsilon2)
Hemoglobin Portland- (zeta2 gamma2)

Just remember:
zeta alpha zeta

Question 17

Compared to adult hgb, Fetal hgb has a _____ oxygen affinity.

Answer 17

higher. This make sense because oxygen needs to be able to transfer from maternal circulation to fetal circulation through the placenta.

Question 18

What cause Fetal hgb to have a higher affinity for O2 than adult hgb?

Answer 18

Fetal hgb binds BPG poorly. This stabilizes hemoglobin in the R state and causes the curve to shift to the left. The Bohr effect is also increase by 20% in fetal hgb. This causes H+ ions to go into maternal circulation as they pass through the placenta. Thus, pH rises in Baby circulation and affinity increases.

Question 19

In normal adults Hgb F makes up what % of blood?

Question 20

What is a Heinz body?

Answer 20

precipitated, denatured hemoglobin

Question 21

High affinity hemoglobins can lead to:

Answer 21

erythrocytosis (too many RBCs).

Question 22

Low affinity Hemoglobins can lead to:

Answer 22

cyanosis

Question 23

erythropoietin is released from the_____

Answer 23

kidney

Question 24

Hemoglobin Zurich is a mutation which causes what to happen?

Answer 24

increased binding to Carbon Monoxide

Question 25

Hemoglobin Koln is a mutation which causes what to happen?

Answer 25

unstable Hemoglobin

Question 26

Heme needs what kind of iron to form itself?

Answer 26

ferrous (2+)

Question 27

The ferric (3+) form of iron leads to what kind of hemoglobin?

Answer 27

methemoglobin. If cannot reduce ferric to ferrous form, leades to methemoglobinemia

Question 28

How is iron maintained in the ferrous form within an RBC?

Answer 28

NADPH methemoglobin reductase pathway

Question 29

What is the most common hereditary cause of methemoglobin?

Answer 29

deficiency of cytochrome b5 reductase

Question 30

with high amounts of methemoglobin, hemoglobin has a _____ ability to carry O2. Also the curve shifts____.

Answer 30

decreased.

left. This further decreases O2 ability to reach the tissues

Question 31

With 8-12% methemoglobin a person becomes

Answer 31

cyanotic but asymptomatic otherwise.

Question 32

Carbon Monoxide poisoning is detected by____?

Answer 32

co-oximetry (not pulse oximetry which cannot differentiate between carboxyhemoglobin and oxyhemoglobin).

Question 33

What is the difference between co-oximetry and pulse oximetry?

Answer 33

Co- measures at 4 wavelengths and can discern between carboxyhemoglobin, oxyhemoglobin and methemoglobin while pulse oximetry absorbs at only 2 wavelengths and cannot differentiate between these two. The both work using light emitting diodes and receptors that measure whats in your blood essentially.