Variation

Question 1

Which individuals are considered genetically identical?

Answer 1

Clones and monozygotic twins

Question 2

Finish the sentence: Monozygotic twins have no genomic differences, but have a few…

Answer 2

epigenetic differences

Question 3

What are the 4 types of variation?

Answer 3

1. Single nucleotide polymorphisms (SNPs)
2. Indels (insertions and deletions)
3. Copy number variations (CNVs)
4. Structural rearrangements

Question 4

Describe allele:

Answer 4

Term to describe alternative forms of a heritable trait

Question 5

Describe polymorphism:

Answer 5

Variation within a population of a given trait

Question 6

What is meant by single nucleotide polymorphism?

Answer 6

Difference at a single nucleotide

Question 7

What is the importance of Single nucleotide polymorphisms?

Answer 7

• Dr James Watson’s genome contained 3.3 million SNPs relative to the human genome project reference, ~0.1% of the genome differed
• approx. 10 million common SNPs in humans
• SNP rate versus chimpanzee ~1%

Question 8

What is indels (insertions/deletions)?

Answer 8

-insertion or deletion of 1 or a few nucleotides

Question 9

What is the significants of indels?

Answer 9

~4 x 105 indel polymorphisms identified in human genome, ~30% of these are tandem repeat expansion polymorphisms

• can be analysed by PCR & gel electrophoresis
• short tandem repeats are multi-allelic
• used in genetic profiling

Question 10

What are short tandem repeats?

Answer 10

Multi-allelic

Question 11

What are the effects of base substitution in coding regions?

Answer 11

• Silent substitution
• Missense substitution
• Nonsense substitution

Question 12

What does missense substitution do to the coding region?

Answer 12

Changes amino acid

Question 13

What does nonsense substitution do to the coding region?

Answer 13

Changes coding for an amino acid to coding for a stop codon

Question 14

What are the effects of base insertion/deletion in coding region?

Answer 14

Cause frame shift to the left or to the right

Question 15

What are the classifications of mutations?

Answer 15

Transition and transversions

Question 16

What does the transition mutation occur between?

Answer 16

Purine to purine or pyrimidine to pyrimidine

Question 17

What does the transversion mutation occur between?

Answer 17

Purine to pyrimidine or to pyrimidine to purine

Question 18

Can small changes in the genome have a large effect on phenotype?

Answer 18

Yes

Question 19

What genetic variation causes sickle cell anaemia?

Answer 19

Single nucleotide polymorphism

Question 20

What genetic variation causes cystic fibrosis or albinism?

Answer 20

Indels

Question 21

What are highly heritable ‘Mendelian’ diseases?

Answer 21

• Variation in a single gene is sufficient to causes diseases
• More than 100 such genes know to humans
• Most diseases are rare

Question 22

Define mutant:

Answer 22

An organism containing a rare allele caused by mutation

Question 23

Define wild type:

Answer 23

The normal allele/organism

Question 24

Does genetic variation have much effect on phenotypic effect?

Answer 24

No, but some exceptions

Question 25

Can base substation have a large or small effect on phenotypic effects?

Answer 25

Large

Question 26

What mutation is more like to produce a rise in non-functional protein?

Answer 26

Frameshift mutation