SCID is an inherited condition in humans. People with some types of SCID are unable to make a functional enzyme necessary for the production of healthy white blood cells. A scientist studying these types of SCID compared features of the DNA and the structure of the enzyme in people who have this condition and people without SCID.
Which of the following features may have been different?
1 the allele of the gene coding for the enzyme
2 the order of amino acids in the enzyme
3 the order of bases in the gene coding for the enzyme
4 the shape of the active site of the enzyme.

Answer:

5) G

1 – Correct
Change in the alleles of the gene coding could have caused the change in DNA.

2 – Correct
The order of amino acids in the enzyme could have changed the protein structure of the enzyme and hence, caused the condition SCID.

3 – Correct
The order of bases in the gene coding could have changed the DNA structure.

4 – Correct
If the shape of the active site is different, then this would have prevented production of healthy white blood cells.

Since all are correct, G is the answer.