D1.3 New

What is a gene mutation?

A change in the DNA sequence of a gene.

What is a base substitution mutation?

One base is replaced by another base.

What is a base insertion mutation?

One or more bases are added to a DNA sequence.

What is a base deletion mutation?

One or more bases are removed from a DNA sequence.

What are the consequences of a base substitution mutation?

It may change an amino acid and alter protein structure; it may also have no effect.

Give an example of a base substitution affecting protein structure.

Sickle-cell disease: a substitution changes an amino acid in haemoglobin, altering its structure.

What are the consequences of base insertion and deletion mutations?

They can change the reading frame, altering the amino acid sequence and protein structure.

Give an example of the consequences of a base insertion.

An inserted base can shift the reading frame, changing downstream amino acids and potentially protein function.

Give an example of the consequences of a base deletion.

A deleted base can shift the reading frame, changing downstream amino acids and potentially protein function.

What are the different causes of mutation?

Mutations can arise spontaneously or be caused by mutagens.

What are examples of mutagens?

Radiation and certain chemicals.

What does randomness in mutation mean?

Mutations occur randomly rather than because an organism needs a particular change.

What are the consequences of mutations in germ cells?

They can be inherited by offspring if the mutation is passed on through a gamete.

What are the consequences of mutations in somatic cells?

They can affect the individual but are generally not inherited by offspring.

How can mutations be a source of genetic variation?

They create changes in DNA that can produce different alleles and genetic differences between individuals.