Hemoglobin

Question 1

How does lead affect iron incorporation into heme?

Answer 1

lead inhibits the incorporation of iron into heme

Question 2

T/F: myoglobin, like hemoglobin, has a sigmoid-shaped O2 binding curve.

Answer 2

false

Question 3

Which enzyme adds iron (II) to protoporphyrin IX to form heme?

Answer 3

ferrochelatase

Question 4

What is the effect of 2,3-BPG on hemoglobin?

Answer 4

it lowers the affinity of oxygen to hemoglobin by binding to the beta subunits of the hemoglobin

Question 5

Hemoglobin is composed of how many polypeptide subunits?

Answer 5

4 (two alpha, two beta)

Question 6

T/F: methemoglobin is an oxidized form of hemoglobin that binds O2 more readily.

Answer 6

F, binds O2 less readily

Question 7

In the liver, heme is conjugated with ___.

Answer 7

glucuronate

Question 8

What is the rate limiting step for the production of heme?

Answer 8

avminolevulinate synthesis

Question 9

Carbon monoxide has a 200x ____ (higher/lower) affinity for hemoglobin than does oxygen.

Answer 9

higher

Question 10

Aminolevulinate synthesis occurs in the ___.

Answer 10

mitochondria

Question 11

Where in the cell does heme synthesis occur?

Answer 11

mitochondria, cytoplasm

Question 12

Name the two organs that are sites for heme synthesis.

Answer 12

liver, bone marrow

Question 13

Is 2,3-BPG essential for life?

Answer 13

Yes

Question 14

Heme synthesis begins with condensation of glycine and succinyl-CoA with decarboxylation to form?

Answer 14

aminolevulinic acid

Question 15

CO2 binding favors which form of hemoglobin? What sort of shift does it cause?

Answer 15

taut form

right shift

Question 16

Increased Cl, H, CO2, DPG, and temperature all cause a shift of the hemoglobin-oxygen dissociation curve to the (left/right).

Answer 16

right

Question 17

Heme catabolism: bilirubin is (toxic/non-toxic) to CNS and transported by ___.

Answer 17

toxic

albumin