There are almost 500 naturally occurring variants of hemoglobin. Most are the result of a single amino acid substitution in a globin polypeptide chain. Some variants produce clinical illness, though not all variants have deleterious effects. Identify the variant or variants that can be described by each of the three statements by placing the letter corresponding to the statement next to the variant. Statement B may describe more than one variant, and a variant may be described by more than one statement. At least one variant will not match any description. A. The Hb variant least likely to cause pathological symptoms. B. The variants most likely to show pI values different from that of HbA on an isoelectric focusing gel. C. The variant most likely to show a decrease in BPG binding and an increase in overall affinity for oxygen.

Hello. You forgot to enter the answer options. The options are:

1. HBd (sickle- Cell HH) substitutes a Val for Glu on the surface.

2. Hg Memphis: Substitutrd one unchanged polar residue for another of similar  size on the surface.

3. Hb Milwaukee: subistitutes a Glu for a Val

4. HB Philly Substitutes a Phe for a Tyr, disrupting hydrogen bonding.

5. Hb Providence: substitutes an Asn for a Lys that normally decrease in BPG binding and an increase in overall affinity for oxygen B C projects into the central cavity of the tetramer

1. HBd (sickle- Cell HH) substitutes a Val for Glu on the surface. (B)

2. Hg Memphis: Substitutrd one unchanged polar residue for another of similar  size on the surface. (A)

3. Hb Milwaukee: subistitutes a Glu for a Val (B)

4. HB Philly Substitutes a Phe for a Tyr, disrupting hydrogen bonding. (B)

5. Hb Providence: substitutes an Asn for a Lys that normally decrease in BPG binding and an increase in overall affinity for oxygen B C projects into the central cavity of the tetramer  (BC)

Explanation:

As you could see in the question above, there are more than 500 variants of Hemoglobin that occur naturally in the body. These variants can trigger the existence of syndromes and biological problems in the body, or not. However, it is important to note that all these variations are caused by simple changes and substitutions in the amino acid chain of hemoglobin that causes changes in the sequences of the nucleotides, interfering in the physicochemical activities of this protein. The severity of these changes depends on the extent of the mutation they caused and where the change took place.

you are certainly talking about this picture:

a: is the label of the white square, it is showing the  replication fork, formed by helicase (d) ==> so it is the site of dna separation and replication 

b: is a new dna brand that is following directly the replication fork, so it is continuous ==> built continuously from 5' to 3

c: dna polymerase cannot replicate dna on its own, it needs the of their proteins, and one of them plays the role of a clamp which fixes  the dna with the dna template and increases  the processivity of the enzyme. ==>   stops polymerase from falling off the  template.

d: is the enzyme responsible for forming the replication fork (helicase) ==> unwinds and separates dna into two strands

e: is the delayed strand, it is built  in the opposite sense of the helicase, so dna will be built in fragments ==> built  fragments from 5' to 3 joins

and finally f: is the enzyme that builds  the new dna strand (dna polymerase) ==>   adds nucleotides to make a new dna helix.

credit: gradman555p98x9p

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