Question

2. A substitution mutation is one in which one nucleotide base is changed to another Suggest ONE substitution A G mutation in the DNA that would cause the first amino acid in the "# of Eyes" gene to change from alanine (Ala) to valine (Val). In the table below, write the original.

3. There is a substitution mutation in the gene for Fangs in which the first DNA base changes from guanine to thymine. The mutation results in a genetic disorder in which the monster's teeth and gums undergo decay and are highly susceptible to bacterial infection. 

a. Describe how this DNA mutation affects/changes the amino acid sequence in the polypeptide. Be specific! 

b. Explain how/why a change in the amino acid sequence of a polypeptide due to a gene mutation can lead to a genetic disorder in an organism.

Answer 1

2:

	Original	Mutation
DNA	CGT	CAT
mRNA	GCA	GUA
Amino acid	Alanine	Valine

3 (a) : Mutation that alters a single nucleotide is termed as point mutation. Since only one nucleotide that is Guanine is changed to Thymine, it is an example of point mutation.

Mutation in DNA will alter the sequence of mRNA. Since mRNA takes part in protein formation (translation) its sequence will also get affected. This will lead to the synthesis of altered / incomplete proteins, and that can lead to disease.

Mutation in DNA --------> Change in the sequence of nucleotide in mRNA -----------> Effect on amino acid sequence ----------> Altered Protein

Proteins are built from 20 buliding blocks, called amino acids.

b: If progeny are to have a good chances at survival, DNA sequence from parents must be passed on largely unchanged. So if there is any mutation in gene of parent it will pass onto the next generation causing genetic disorder.