Genetics of living systems chp 19 DONE THIS ON OTHER DECK

Question 1

what is a mutation when talking about DNA

Answer 1

• a change in the sequence of bases in DNA

Question 2

what are the 3 difference types of change in the sequence of DNA bases

Answer 2

• substitution
• deletion
• insertion

Question 3

what is it called when only one nucleotide is affected by mutation

Answer 3

• point mutation

Question 4

what is meant when the genetic code is called degenerate

Answer 4

a single amino acid may be coded for by more than one codon.

Question 5

what does the substitution of a single nucleotide change

Answer 5

the codon in which it occurs

Question 6

what type of mutation does insertion and or deletion cause

Answer 6

frameshift mutation

Question 7

define reading frame/triplet code

Answer 7

• way of dividing sequence of nucleotides in a nucleic acid molecule (RNA/DNA) into codons

Question 8

how does insertion/deletion cause frameshift

Answer 8

it moves/shifts the reading frame of the sequence of bases.
^this will change every successive codon from the point of the mutation

Question 9

under what conditions could insertion/deletion not result in frameshift

Answer 9

• if the number of nucleotides added or deleted are multiples of 3
  ^as they would correspond to full codons and the reading frame would not be changed
• ^the protein formed will still be affected as an amino acid is added or deleted

Question 10

what are the effects of different mutations

Answer 10

• no effect - because normally functioning proteins are still synthesised
• damaging - organism affected in negative way because proteins are no longer synthesised or proteins synthesised are non-functional
• beneficial - very rare, protein synthesised results in new and useful characteristics in phenotype.

Question 11

what is a mutagen

Answer 11

a chemical, physical or biological agent which causes mutations

Question 12

what is the loss of purine and pyrimidine bases called

Answer 12

• loss of purine base is called depurination
• loss of pyrimidine base is called depyrimidination

Question 13

how can the absence of a base lead to insertion

Answer 13

can lead to insertion of an incorrect base through complementary base pairing during DNA replication

Question 14

how can free radicals cause mutations

Answer 14

• can affects the structure of nucleotides
• disrupt base pairing during DNA replication

Question 15

what’s the difference between gene and chromosome mutations

Answer 15

gene mutations occur in single genes or sections of DNA whereas chromosomes mutation affect the whole chromosome or number of chromosomes within a cell

Question 16

what are some ways that chromosomes can mutate

Answer 16

• deletion - a section of chromosome breaks off and is lost within the cell
• duplication - sections get duplicated on a chromosome
• translocation - a section of one chromosome breaks off and joins another non-homologous chromosome
• inversion - a section of chromosome breaks off, is reversed and then joins back onto the chromosome

Question 17

define codon

Answer 17

• set of consecutive, non-overlapping triplets in a nucleic acid molecule (RNA/DNA)