Researchers compared the amino acid sequences of the transport protein in zebrafish, puffer fish, mice, and humans. They found many stretches with identical sequences in all four species. Does this mean that the corresponding mRNA base sequences are also the same in these four species? Explain why or why not.

A) No because the redundancy of the genetic code means that it is possible for deferent codons to specify the same amino acids

B) Yes, because the amino acid sequences synthesized on base of mRNA sequence base is a result of translation, so if amino acid sequences are identical, the mRNA base sequences will be identical too.

C) Yes, because ail codons specify the same amino acids in all organisms.

D) No, because stretches with identical sequences in this species mean that the corresponding rRNA base sequences are also the same.

A) No because the redundancy of the genetic code means that it is possible for different codons to specify the same amino acids

Explanation:

There are 20 amino acids in nature whereas, there are 64 possible codons from 4 bases (adenine, guanine, uracil, and cytosine). Consequently, an amino acid can be coded for by more than one genetic codes. This is why the genetic codes are said to be redundant/degenerate.

Hence, having similar stretches of amino acid by the same organism does not corresponds to similar mRNA base sequence. For example, the codons UCC, UCU, UCA, and UCG all codes for the same amino acid serine.

The correct option is A.

A) No because the redundancy of the genetic code means that it is possible for deferent codons to specify the same amino acids

Explanation:

Redundancy in the genetic code makes that differences in the messenger RNA (mRNA) to be translated into the same amino acids, thereby differences in the mRNA might encode for the same protein sequence  

an individual’s sex (i.e., whether they are a male or female) is determined by the sex chromosomes. most people have two sex chromosomes, one that is inherited from their mother and one that is inherited from their father. typically, females have two x chromosomes (xx) and males have one x chromosome and one y chromosome (xy). conditions caused by changes (“mutations”) in genes located on the x chromosome are considered x-linked.

x-linked recessive inheritance

most x-linked conditions are recessive. this means that in a person with two x chromosomes (most females), both copies of a gene (i.e., one on each x chromosome) must have a change or mutation whereas in a person with one x chromosome (most males), only one copy of a gene must have a mutation. a female with a mutation in one copy of a gene on the x chromosome is said to be a “carrier” for an x-linked condition. a male with a mutation in a gene on the x chromosome is typically affected with the condition. because females have two copies of the x chromosome and males have only one x chromosome, x-linked recessive diseases are more common among males than females. however, x-linked recessive diseases can occur in both males and females.

for x-linked recessive disorders, an unaffected carrier mother who has a mutation in a gene on the x chromosome can transmit either the x chromosome with this mutation or a “normal” x chromosome to her children. if the father is unaffected, none of her daughters will be affected and all of her daughters will be unaffected—since they will inherit at least one normal x chromosome from their father. however, each daughter will have a 50% chance of being an unaffected carrier like her mother and a 50% chance of both x chromosomes being normal.