1.5 Genome and mutations

Question 1

Genome of an organism

Answer 1

• consists of all the genetic information encoded in the DNA of a complete set of an organisms chromosomes
• not exclusively made of genes
• only a small portion of the genome is made of coding genes in eukaryotes

Question 2

Roles of non-coding DNA

Answer 2

• regulate transcription
• some transcribed but never translated

Question 3

Mutation

Answer 3

a change in the DNA that can result in no protein or an altered protein being produced

Question 4

Main types of mutation

Answer 4

• Single gene mutations
• chromosome structure mutations

Question 5

Types of single gene mutations

Answer 5

• substitution
• insertion
• deletion

Question 6

substitution mutation

Answer 6

replacing a base (minor change)

Question 7

insertion mutation

Answer 7

adding an extra base (major change - shifted forward)

Question 8

deletion mutation

Answer 8

removing a base (major change - shifted back)

Question 9

Types of substitution mutations

Answer 9

• missense
• nonsense
• splice site

Question 10

missense mutation

Answer 10

one nucleotide is replaced by another (causing one amino acid being changed for another)

Question 11

nonsense mutation

Answer 11

causes a premature stop codon to be produced, resulting in a shorter protein

Question 12

splice site mutation

Answer 12

can cause introns to be retained and exons to be removed from the mature transcript

Question 13

Frameshift mutations

Answer 13

• insertion
• deletion
• causes all the codons after the mutation to change, causing all amino acids to be changed
• this has a major effect on the protein produced

Question 14

types of chromosome mutations

Answer 14

• duplication
• deletion
• inversion
• translocation

Question 15

duplication chromosome mutation

Answer 15

when a section of chromosome is added from its homologous partner

Question 16

deletion chromosome mutation

Answer 16

when a section of chromosome is removed

Question 17

inversion chromosome mutation

Answer 17

when a section of chromosome is reversed

Question 18

translocation chromosome mutation

Answer 18

when a section of chromosome is added to another that is not its homologous partner

Question 19

why are chromosome mutations often lethal

Answer 19

because of the substantial changes

Question 20

what are mutations the only source of

Answer 20

new alleles

Question 21

what would happen without mutations

Answer 21

there would be no evolution

Question 22

what do duplicated genes allow

Answer 22

potential beneficial mutations to occur while the original gene can still be expressed to produce its protein