Exploring Point Mutations

9 Questions

What are the two basic types of base-pair substitutions that alter amino acids?

Missense and nonsense mutations

What is the consequence of a nonsense mutation?

Premature termination of the polypeptide chain

Which of the following is true about tandem repeats in a normal person?

They increase in number during meiosis or early fetal development

What happens when tandem repeats increase in number in certain regions of the genome?

They cause genetic diseases

How many genetic diseases are known to be caused by expanded repeats?

Around 20

Which type of mutation can alter the downstream codons and result in a frameshift mutation?

Deletions and insertions

What is the consequence of a frameshift mutation?

Truncated polypeptide

Which gene is associated with Charcot–Marie–Tooth disease when duplicated?

PMP22

Which type of mutation can cause partial deletion or complete deletion of an exon?

Splice-site mutations

Study Notes

Types of Base-Pair Substitutions

Two basic types of base-pair substitutions that alter amino acids: transitions and transversions

Consequences of Mutations

Consequence of a nonsense mutation: premature termination of protein synthesis

Tandem Repeats

In a normal person, tandem repeats are stable and their number remains consistent
When tandem repeats increase in number in certain regions of the genome: it can cause disease
Number of genetic diseases known to be caused by expanded repeats: over 40

Frameshift Mutations

Type of mutation that can alter downstream codons and result in a frameshift mutation: insertion or deletion of nucleotides
Consequence of a frameshift mutation: complete change in the amino acid sequence and often leads to a non-functional protein

Gene Associated with Charcot–Marie–Tooth Disease

Gene associated with Charcot–Marie–Tooth disease when duplicated: peripheral myelin protein 22 (PMP22)

Types of Mutations

Type of mutation that can cause partial deletion or complete deletion of an exon: exon deletion