Question

Explain how a mutation in DNA can affect an organism’s traits.
Include how DNA, mRNA, amino acids, and proteins are connected, and describe an example such as sickle cell anemia or camouflage.

​​​​(4 points)
0 / 10000 Word Limit

Answer 1

1) Mutation in DNA: a change to the nucleotide sequence (substitution, insertion, deletion) alters the gene’s instructions.

2) DNA → mRNA (transcription): the mutated DNA is copied into mRNA. A change in the DNA sequence changes the mRNA codon(s).

3) mRNA → amino acids (translation): ribosomes read mRNA codons; each codon specifies an amino acid. A changed codon can (a) code for a different amino acid (missense), (b) become a stop codon (nonsense), (c) leave the same amino acid (silent), or (d) shift the reading frame (frameshift), which usually changes many downstream amino acids.

4) Amino acids → protein → trait: the sequence of amino acids determines a protein’s shape and function. An altered amino acid sequence can change protein folding, stability, or activity, which changes cell behavior and can alter an organism’s traits.

Example — sickle cell anemia:
- Cause: a single base substitution in the beta-globin gene changes the 6th codon from GAG (glutamic acid) to GUG (valine).
- Effect on protein: one amino acid (hydrophilic Glu → hydrophobic Val) in hemoglobin causes the hemoglobin molecules to stick together and form long fibers under low oxygen.
- Effect on cells/trait: red blood cells become sickle-shaped, break down more easily, and can block small blood vessels → anemia, pain, and organ damage.

Summary: a single DNA change can propagate through transcription and translation to alter a protein and thereby change an organism’s observable traits.