19.1 Mutations And Variation

Question 1

What are the three types of mutations that cause a change in the sequence of bases in dna

Answer 1

Substitution
Deletion
Insertion

Question 2

What is a point mutation

Answer 2

If only one nucleotide is affected

Question 3

What mutations cause a frameshift mutation

Answer 3

Insertion or deletion

They move/shift the reading frame of the sequence if bases therefore changing every successive codon

Question 4

What are the 3 affects of different mutations

Answer 4

No effect
Damaging - proteins are no longer synthesised and can interfere with essential processes
Beneficial - new and useful characteristics in phenotype

Question 5

What causes mutations

Answer 5

Mutagens

Question 6

What are physical mutagens

Answer 6

Ionising radiations
Xrays
Break strands of dna

Question 7

What are chemical mutagens

Answer 7

Deaminating agents

Chemically alter bases in dna

Question 8

What biological agents causes mutations

Answer 8

Alkylating agents - methyl/ethyl attached to bases
Base analogs - incorporated in place of a usual base
Viruses - viral dna may insert itself into a genome

Question 9

What is a silent mutation

Answer 9

Means they don’t change any proteins or the activity of any proteins synthesised

Question 10

What is a nonsense mutation

Answer 10

Result in a codon becoming a stop codon Instead of coding for an amino acid
They have negative effects

Question 11

What is a missense mutation

Answer 11

Incorporation of an incorrect amino acid into the primary structure of a protein
Effect can be silent beneficial or harmful

Question 12

What are chromosome mutations

Answer 12

Affect the whole chromosome or number of chromosomes within a cell

Question 13

What changes in chromosome structure do chromosome mutations cause

Answer 13

Deletion
Duplication
Translocation - section of chromosome breaks off and joins another non-homologous chromosome
Inversion - section of chromosome breaks off, is reversed and then joins back onto the chromosome