Hemoglobin Flashcards
How does lead affect iron incorporation into heme?
lead inhibits the incorporation of iron into heme
T/F: myoglobin, like hemoglobin, has a sigmoid-shaped O2 binding curve.
false
Which enzyme adds iron (II) to protoporphyrin IX to form heme?
ferrochelatase
What is the effect of 2,3-BPG on hemoglobin?
it lowers the affinity of oxygen to hemoglobin by binding to the beta subunits of the hemoglobin
Hemoglobin is composed of how many polypeptide subunits?
4 (two alpha, two beta)
T/F: methemoglobin is an oxidized form of hemoglobin that binds O2 more readily.
F, binds O2 less readily
In the liver, heme is conjugated with ___.
glucuronate
What is the rate limiting step for the production of heme?
avminolevulinate synthesis
Carbon monoxide has a 200x ____ (higher/lower) affinity for hemoglobin than does oxygen.
higher
Aminolevulinate synthesis occurs in the ___.
mitochondria
Where in the cell does heme synthesis occur?
mitochondria, cytoplasm
Name the two organs that are sites for heme synthesis.
liver, bone marrow
Is 2,3-BPG essential for life?
Yes
Heme synthesis begins with condensation of glycine and succinyl-CoA with decarboxylation to form?
aminolevulinic acid
CO2 binding favors which form of hemoglobin? What sort of shift does it cause?
taut form
right shift
Increased Cl, H, CO2, DPG, and temperature all cause a shift of the hemoglobin-oxygen dissociation curve to the (left/right).
right
Heme catabolism: bilirubin is (toxic/non-toxic) to CNS and transported by ___.
toxic
albumin
