*Please answer the following questions. For clarification please provide a short
ID: 11415 • Letter: #
Question
*Please answer the following questions. For clarification please provide a short explanation for the answer you chose
Please note, hemoglobin will be abbreviated as xyz
The difference between fetal and adult xyz with regards to O2 binding:
a.) is due to a change in the primary structure when comparing the 2
b.) manifest because fetus xyz has 1 less + charge than adult xyz
c.) is due to fetus xyz having a S rather than an H at a defined point in the protein
d.) results because the fetal xyz binds less tightly to BPG than adult xyz
e.) all of the above
Explanation / Answer
Please note, hemoglobin will be abbreviated as xyz
The difference between fetal and adult xyz with regards to O2 binding:
a.) is due to a change in the primary structure when comparing the 2
b.) manifest because fetus xyz has 1 less + charge than adult xyz
c.) is due to fetus xyz having a S rather than an H at a defined point in the protein
d.) results because the fetal xyz binds less tightly to BPG than adult xyz
e.) all of the above The answer is all of them - the binding is tighter because of a combination of structural (protein) and electrical (i.e. the charge referenced in b) conditions:
In the tetrameric form of normal adult haemoglobin, the binding of oxygen is, thus, cooperative.
In the fetal hemoglobin, the binding of oxygen binds with greater affinity than adult haemoglobin. This means that the oxygen binding curve for fetal haemoglobin is left-shifted (i.e., a higher percentage of haemoglobin has oxygen bound to it at lower oxygen tension), in comparison to that of adult haemoglobin.
Besides the oxygen ligand, which binds to haemoglobin in a cooperative manner, haemoglobin ligands also include competitive inhibitors such as carbon monoxide (CO) and allosteric ligands such as carbon dioxide (CO2) and nitric oxide (NO). The carbon dioxide is bound to amino groups of the globin proteins as carbaminohaemoglobin, and is thought to account for about 10% of carbon dioxide transport in mammals. Nitric oxide is bound to specific thiol groups in the globin protein to form an S-nitrosothiol which dissociates into free nitric oxide and thiol again, as the haemoglobin releases oxygen from its haem site. This nitric oxide transport to peripheral tissues is hypothesised to assist oxygen transport in tissues, by releasing vasodilatory nitric oxide to tissues in which oxygen levels are low
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