Lecture 17 - Genetic Mutations I

These flashcards cover key concepts from Lecture 17 on Genetic Mutations, including definitions, types of mutations, and their implications.

What is the definition of a wild type in genetics?

The normal or default DNA sequence that is most common for a particular chunk of DNA.

What does a mutation refer to?

Any change in DNA sequence from the wild-type, regardless of effects.

What is a conditional mutation?

Mutations where the impact is only observed under specific conditions.

What is a silent mutation?

A mutation that is not detectable in phenotype and can be found only through DNA sequencing.

What are point mutations?

Mutations that occur at a specific point in DNA and only involve 1-5 nucleotides.

What are the three main types of point mutations?

1) Base substitution (swap), 2) Base deletion (remove), 3) Base insertion (add).

What happens during deamination of cytosine?

Cytosine interacts with water, producing uracil and ammonia, which can lead to permanent genetic changes if not repaired.

What is depurination?

The spontaneous hydrolysis of the glycosidic bond between a nitrogenous base and a pentose sugar.

What is an apurinic nucleotide?

A nucleotide without an attached base.

What is the effect of a thymine dimer on DNA?

It causes the DNA backbone to distort, potentially leading to replication errors.

What are chemical mutagens?

Chemicals that alter the structure of a base so it will base-pair with an inappropriate complement.

What is a repair mechanism in genetics?

It removes and replaces damaged DNA to restore the original sequence.

What is the difference between reversion and reversal?

Reversion restores the original function without restoring the original sequence; reversal restores the original sequence.

What is an example of intragenic reversion?

A second mutation occurs in the same gene as the first, reversing the impact of the original mutation.

What is a suppressor tRNA?

A mutant tRNA that binds to STOP codons and allows translation to continue.

What is the significance of having multiple STOP codons in a sequence?

It provides a backup to protect against reverse nonsense mutations.