Point mutations can impair a protein if they result in a: (Select all that apply.) nonsense codon. synonymous codon. shift in reading frame. nonsynonymous codon.

The mutation that affects the single nucleotide of nucleic acid are called as point mutation. It includes substitution, insertion or deletion of single base pair.

When a premature nonsense or stop codon is inserted in the DNA sequence nonsense mutation occurs such as UAU is replaced by UAA (stop codon).
A single nucleotide is added or deleted (shift in reading frame) in frame shift mutation.
The amino acid are changed because of change in codon (nonsynonymous codon) by missense mutation.
The mutation does not change the codon thus does not change the amino acid (synonymous codon) and does not express it are called as silent mutation.

eyitbay eyitbay · Answer 2 · 2020-03-03T12:09:59+01:00

Answer:

nonsense codon.. shift in reading frame. nonsynonymous codon.

Explanation:

Point mutation is the type of mutation which cause a change in a single nucleotide of a nucleic acid. It occurs by replacing or substituting a single purine or pyrimidine on one DNA strands with a change in the corresponding purines and pyrimidine on the other complementary DNA strands, and therefore synthesis of a different polypeptides protein chain.

E.g. Substitution of amino acid Glu. with Valine produces abnormal protein sequence which leads to sicked shaped haemoglobin in sickle cell anemia.

When point mutations results from replacement of single nucleotides bases in DNA with new uncomplimentary base not matching the triplet code;it is refers to as frame shift .It results in coding for an entirely new amino protein sequence. It also occurs by changing the first stop codon,(stop-gain or stop-loss) shifting the triplet code,producing short length of DNA sequence different from the original transcribed DNA sequence. or extending the process of translation due to loss of stop codon therefore entirely new longer length of proteins formed.

It can be due to genetic effects or exposure to certain environmental factors.

Generally when a point mutation results in a change in corresponding amino acid sequence in the protein from the original transcribed DNA sequence, non synonymous codon is formed. This is non synchronous mutation.(Ka)(but if no complementary change occurs it is refers to as( synonymous mutation( Ks).

A type of non-synonymous mutation is nonsense mutation from nonsense codon. It occurs when point mutation results in substitution of the original single base with a stop codon; (stop-gain).Therefore the base termination occurs abruptly , shortened the length of the amino acid sequence and thus affecting the functions of the intended protein.