Mutations 1.6

Question 1

What are Mutations

Answer 1

Changes in an organism’s DNA, either the quantity or structure is altered - changes to the genome.

Question 2

Mutagenic Agents

Answer 2

Radiation (UV and Xrays)
Chemicals (Mustard Gas and Cigarette Smoke)
Infections (HPV)

Question 3

What are Single Gene Mutations?

Answer 3

The alteration of a DNA nucleotide sequence as a result of substitution, insertion or deletion. Aka point mutations.

Question 4

What are Missense Mutations

Answer 4

A different amino acid is made. Proteins could be non-functional or it could have little effect on the protein. Makes sense but not the original sense.

Question 5

What is a single gene substituation reaction?

Answer 5

One nucleotide is ‘substituted’ for another, one is removed from the sequence and replaced with another. These can result in missense, nonsense and splice-site mutations

Question 6

What are Nonsense Mutations

Answer 6

A stop codon is made so a shorter polypeptide is produced as a result.

Question 7

What are Silent Mutations?

Answer 7

The same amino acid is made

Question 8

What are neutral mutation?

Answer 8

A SIMILAR amino acid is made

Question 9

What are Splice Site Mutations

Answer 9

Mutations in the area that marks the start or end of an intron may lead to one or more introns remaining in the mature transcript also some exons might not be included in the mature transcript. This leads to the creation of a protein that does not function normally.

Question 10

What is a single gene insertion?

Answer 10

One or more nucleotides are ‘inserted’ into a section of DNA. At least one additional nucleotide is added to the sequence.

Question 11

What is a single gene deletion?

Answer 11

One or more nucleotides are removed from a section of DNA and not replaced

Question 12

Define Frameshift Mutations

Answer 12

If an insertion or deletion occurs, all bases downstream are moved from their place, this alters all of the codons from the mutation onwards, thus all amino acids are changed and this has a major effect on the protein produced.

Question 13

What is the evolutionary importance of gene mutations?

Answer 13

Mutation is the only source of variation/new alleles of a gene.

Question 14

What are Chromosome Structure Mutations?

Answer 14

Alteration to whole sections of chromosomes affecting several genes. Can be a result of; duplication, deletion, inversion or translocation.

Question 15

What is Chromosome Structure duplication?

Answer 15

A section of a chromosome becomes attached to it’s matching (homologous) chromosome leading to repeated genes.

Question 16

What is the evolutionary importance of duplication?

Answer 16

Duplication produces a second copy of the gene which is free from selection pressure. The extra copy can mutate to produce new DNA sequences with a possible selective advantage.

Question 17

What is Chromosome Structure Deletion?

Answer 17

Sections of the chromosome is removed as a region of DNA are left out during replication, therefore some genes re lost completely.

Question 18

What is Chromosome Structure Inversion?

Answer 18

The chromosome breaks in two places and rotates through 180 degrees. The sequence of the gens in this section are reversed, often results in the formation of non-viable gametes since chromosome pairing cannot occur.

Question 19

What is Chromosome Structure Translocation?

Answer 19

A section of chromosome becomes attached to a different chromosome (not its homologous partner) This results in problems pairing chromosomes during gamete formation and leads to non-viable gametes.

Question 20

The Effects of Chromosome Mutations

Answer 20

Lethal