mutations

Question 1

what is a mutation

Answer 1

a change in the sequence of bases in DNA

Question 2

what are the 3 types of mutations

Answer 2

• substitution
• deletion
• insertion

Question 3

what is a frameshift mutation

Answer 3

• caused by insertion or deletion
• will change every consecutive codon from the point of the mutation

Question 4

mutations with no effect (silent)

Answer 4

• no effect on the phenotype of the organism because normally functioning proteins are still synthesised
  causes:
• degenerate nature of DNA means that a base changed but the codon still coded for the same amino acid
• mutation produces triplet that codes for a different amino acid, but this amino acid is chemically similar to the og so it functions the same (conservative mutation)
• mutated triplet codes for a amino acid not necessary for the proteins function
• mutation occurred in intron

Question 5

beneficial mutations

Answer 5

• rarely, a protein is synthesised that results in a new useful characteristic in the phenotype which are passed down generations through natural selection e.g. bacterial antibiotic resistance

Question 6

harmful mutations

Answer 6

• phenotype is affected negatively because proteins are no longer synthesised (mutation at the start of gene so RNA polymerase cant bind) or are non-functional which interfere with essential processes
• e.g. CF caused by deletion of 3 bases in the gene that codes for CF transmembrane conductance regulator protein

Question 7

causes of mutations

Answer 7

• occurs spontaneously, often during DNA replication
• rate of mutation is increased by mutagens (chemical/physical/biological agent)

Question 8

nonsense mutations

Answer 8

• result in a codon becoming a stop codon instead of coding for an amino acid
• results in short protein which is normally non-functional

Question 9

missense mutations

Answer 9

• result in incorporation of an incorrect amino acid into the primary structure when the protein is synthesised
• could be silent, beneficial or harmful

Question 10

what are chromosome mutations

Answer 10

• affect the whole chromosome/ no. of chromosomes instead of a single gene
• can be caused by mutagens
• can be silent
• include deletion, duplication, translocation, inversion

Question 11

what is chromosome deletion

Answer 11

section of chromosome breaks off and is lost within the cell

Question 12

what is chromosome duplication

Answer 12

sections get duplicated on a chromosome

Question 13

what is chromosome translocation

Answer 13

section of one chromosome breaks off and joins another non-homologous chromosome

Question 14

what is chromosome inversion

Answer 14

section of chromosome breaks off, is reversed, and joins back onto the chromosome