Gene Mutations and Their Effects

Practice flashcards covering the causes of DNA mutations, mutation rates, alleles, point mutations, and frameshift mutations based on lecture notes.

What factors can cause DNA mutations according to the lecture?

Mutations can be caused by spontaneous errors in replication, chemical changes in the DNA, chemically induced mutations, or radiation.

On average, how frequently do unrepaired mistakes in DNA replication occur in humans?

Unrepaired mistakes in DNA replication occur on average one in $100\text{ million}$ bases.

How is an allele defined in the lecture?

An allele is defined as any variation in DNA sequence.

What is a point mutation?

A point mutation is a single base substitution where one base in the DNA is changed to another.

What are the three types of point mutations discussed in the lecture?

The three types of point mutations are missense mutations, silent mutations, and nonsense mutations.

What occurs during a silent mutation?

A silent mutation is a single base substitution that results in no change to the amino acid sequence.

What occurs during a missense mutation?

A missense mutation is a single base substitution that results in one amino acid being changed to another.

What occurs during a nonsense mutation, and what is its effect on the resulting protein?

A nonsense mutation is a single base change that converts an amino acid codon into a stop codon, signaling translation to stop and resulting in a shorter protein.

What is a reading frame?

The reading frame is the sequence of codons starting with the start codon.

What causes a frameshift mutation, and how does it affect the reading frame?

A frameshift mutation is caused by an insertion or deletion of bases that is not a multiple of $3$, which alters the entire reading frame and codon sequence from the mutation onward.

How does an insertion or deletion of a multiple of $3$ bases affect the protein differently than a frameshift mutation?

Insertions or deletions that are a multiple of $3$ do not cause a frameshift; instead, they simply add or delete one or more amino acids without altering the subsequent reading frame.

How do silent, missense, nonsense, and frameshift mutations compare regarding their potential effects on protein function?

Frameshift, nonsense, and missense mutations can have potentially large or drastic effects on protein structure and function, whereas silent mutations likely will not.