Variation

Question 1

Define mutation

Answer 1

An inherited change in genetic information

the only way that genetic variation can be created

Question 2

What are genetic mutations caused by?

Answer 2

• copying errors
• exposure to radiation or chemicals
• viruses or virus-like sequences

Question 3

What are the 3 classes of mutation?

Answer 3

• point: change in a single nucleotide
• transposable elements: large segments of DNA that ‘jump about’
• chromosomal mutations: eliminate, duplicate, or rearrange segments

Question 4

What are the 3 types of point mutation?

Answer 4

• substitutions
• deletions
• insertions

Question 5

What is a substitution?

What are the 2 types?

Answer 5

one base is substituted for another

• transition: purine -> purine or pyrimidine -> pyrimidine
• transversions: purine pyrimidine

Question 6

What is a neutral mutation?

Answer 6

Occurs in non-coding region so there is no effect on the coding for proteins

Question 7

What is a silent mutation?

Answer 7

Occurs in a coding sequence of DNA, but because of the redundancy of the genetic code, the new codon codes for the same amino acid.

Question 8

What is a coding mutation?

Answer 8

causes the change in the amino acid

Question 9

What is a non sense mutation?

Answer 9

the new codon is a start or stop codon

Question 10

What type of mutation are neutral mutations, silent mutations, coding mutations, and non-sense mutations?

Answer 10

Substitutions

Question 11

What are indels?

Answer 11

Deletion: one or more nucleotide(s) are deleted from the DNA sequence

Insertions: one or more nucleotide(s) are inserted into the DNA sequence

Question 12

What is the impact of a indel?

Answer 12

• The reading frame of the gene shifts (frameshift) unless a whole codon is inserted or deleted
• Downstream is affected

Question 13

What is a mutational hotspot?

Answer 13

Certain sites in DNA molecules that have more frequent insertions and deletions.

e.g. repetitive sequences

Question 14

What is slippage?

Answer 14

DNA slipping relative to each other usually in repetitive sequences.
The two strand malign which can cause crossing over, resulting in one strand longer than the other.

Question 15

What are the 3 types of chromosomal mutations?

Answer 15

• Chromosome rearrangements
• Aneuploids
• Ployploids

Question 16

What is an aneuploid?

Answer 16

A chromosome rearrangement where there is a change in the number of individual chromosomes.

Question 17

What is a polyploid?

Answer 17

A chromosomal rearrangement where one or more complete sets of chromosomes are added, either form the same species (autopolyploids) or as a result of hybridisation between two different species (allopolyploids)

Question 18

How do deletions and insertions occur in chromosomal rearrangement?

Answer 18

Crossing over if the chromosomes aren’t lined up can cause different sized daughter cells

Question 19

What are the 6 main processes that shape the size, complexity and organization of genomes.

Answer 19

1. Exon shuffling
2. Chromosomal rearrangement
3. Whole genome duplication
4. Horizontal gene transfer
5. Mobile elements

Question 20

Give an example of a region of DNA that evolves quickly.

Answer 20

Human Accelerated Region (HAR1F)

• involved in neuron development
• short sequence

Very different bilogical groups have a similar HAR1F (like a chimp and a chicken) while similar groups are different (like a human and chimp)

Question 21

What is a molecular clock?

Answer 21

Using the known rate of change of particular DNA sequences through time to estimate the time of divergence of taxa.

Must be carefully calibrated which can be done with fossils.