Structure of the Genome and Mutation

Question 1

What is the genome of an organism?

Answer 1

The total genetic information encoded into the base sequence of its DNA

Question 2

What types of sequences does the genome contain?

Answer 2

Those that code for protein (genes) and those that do not

Question 3

What genetic sequences that are contained in the genome, do not code for proteins?

Answer 3

Introns, regulators of transcription and those that are transcribed into RNA but not translated

Question 4

What is the function of: coding sequences (genes)?

Answer 4

To code for amino acid sequences in proteins

Question 5

What is the function of: non-coding sequences?

Answer 5

Regulate transcription via turning genes on and off, others are unknown

Question 6

What are mutations?

Answer 6

Mutations are rare, random changes to DNA sequences

Question 7

What is the effect of single gene mutation?

Answer 7

No protein, or an altered protein is produced

Question 8

What is the effect of mutations at splice sites?

Answer 8

Can cause introns to be left in mature mRNA, leading to an altered protein

Question 9

What is the effect of chromosome mutation?

Answer 9

Affects structure of chromosomes present in cells

Question 10

Where does single gene mutation occur?

Answer 10

Within genes

Question 11

What do single gene mutations involve?

Answer 11

The alteration of a DNA nucleotide sequence

Question 12

What do gene mutations result in?

Answer 12

No protein, or an altered protein being expressed

Question 13

What are the three types of gene mutation?

Answer 13

Substitution - A single nucleotide is removed and replaced by another with a different base, Insertion - Additional nucleotide added into a DNA sequence, Deletion - Nucleotide removed from a DNA sequence with no replacement

Question 14

What is the impact of Substitution on protein structure?

Answer 14

Substitution results in a minor impact since there is a maximum of one amino acid changed in the protein structure this is called missense, thought a Major impact could occur if mutation results in the production of a premature stop codon, this is called nonsense

Question 15

What is the impact of Insertion and Deletion?

Answer 15

Major effect on protein structure likely since all amino acids codded for after the mutation could be affected, sometimes called frame-shift mutation

Question 16

What is the effect of a single gene mutation at a splice site?

Answer 16

May result in an intron being left in the mature mRNA or an exon being left out, this could result in a protein that would not function normally

Question 17

What is the significance of gene mutation in evolution?

Answer 17

Mutation provides the only source of new variation for living organism and so has vital importance in evolution

Question 18

How do chromosome mutations occur?

Answer 18

When pieces of the chromosome break off and are lost or join back into the chromosome complement in a different way

Question 19

What are the 4 types of chromosome mutations?

Answer 19

Deletion - Detached genes are lost completely, Inversion - Chromosome breaks in two place and a set of genes rotates through 180 degrees, Translocation - Detached genes become attached to a non-homologous chromosome in the complement, Duplication - A set of genes from one chromosome becomes attached to its homologous partner, leading to repeated genes

Question 20

Discuss chromosome mutations and evolution

Answer 20

It is thought that duplicated genes can undergo single gene mutations without affecting the function of the original gene