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Genetics > Lecture 8 - Genetic Variation, Genomes And Mutation > Flashcards

Lecture 8 - Genetic Variation, Genomes And Mutation Flashcards

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1
Q

What is the arrangement of eukaryotic genomes?

A

Linear chromosomes

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2
Q

How many somatic chromosomes are in the main genome of the nucleus?

A

22 somatic chromosomes

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3
Q

What is the size of the human mitochondrial genome?

A

16,500 bp

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4
Q

What are the key components of chromosome 22?

A
  • Centromere
  • 2 telomeres
  • Origins of replication
  • Heterochromatin
  • Intergenic regions
  • UTRs
  • Promoters
  • Introns
  • Protein coding regions
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5
Q

What percentage of the human genome is made up of protein-coding exons?

A

1.5%

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6
Q

Define LINEs in the context of genetics.

A

Long interspersed nuclear elements

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7
Q

Define SINEs in the context of genetics.

A

Short interspersed nuclear elements

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8
Q

What are transposons often referred to as?

A

Jumping genes

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9
Q

What are the two categories of transposition?

A
  • Cut and paste transposition: gone from donor DNA
  • Replicative transposition: still in donor DNA
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10
Q

What is the role of retrotransposons?

A

Transpose via mRNA

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11
Q

What is reverse transcription?

A

mRNA to DNA

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12
Q

What is the definition of an allele?

A

Alternative forms of a heritable trait

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13
Q

What is the definition of polymorphism?

A

Variation within a population of a given trait

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14
Q

Name the types of variation in genetics.

A
  • Single nucleotide polymorphisms (SNPs)
  • Indels (insertions or deletions)
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15
Q

How many SNPs are approximately found in humans?

A

About 10 million SNPs

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16
Q

What are the effects of base substitutions?

A
  • Silent: doesn’t change amino acid
  • Missense: changes amino acid
  • Nonsense: changes amino acid to stop codon
17
Q

What is a phenotypic effect of sickle cell anemia?

A

Single nucleotide polymorphism of adenine to thymine in beta-haemoglobin gene

18
Q

What happens to coding regions after a base insertion?

A

Frameshift mutation occurs

19
Q

What is an example of a disease caused by an indel?

A
  • Cystic fibrosis
  • Albinism
20
Q

What are Mendelian diseases?

A

Disorders caused by variation in a single gene

21
Q

What technology is used in Oxford Nanopore sequencing?

A

Small flow cell with nanopores that a DNA strand passes through then the signal is decoded to discover the sequence (each base gives a different signal)

22
Q

What mechanisms do cells have to prevent mutations?

A
  • Proofreading DNA polymerase
  • Post-replication mismatch repair
  • DNA repair by homologous recombination
  • Cell cycle checkpoints
23
Q

What are somatic cell mutations primarily associated with?

A

Cancers

24
Q

What is a mutagen?

A

Substance that causes mutations

25
Q

What type of damage does UV light cause?

A

Point mutations

26
Q

What are intercalating agents?

A

Flat molecules that insert between base pairs causing frame shift mutations

27
Q

What is the effect of base analogues?

A

Incorporated into DNA in place of normal base due to their similar molecular structure to the bases

28
Q

What are base modifying agents?

A

Covalently alter bases causing mispairing such as deaminating (removes amino group), hydroxylating (add hydroxyl group) and alkylating (add alkyl groups)

29
Q

What are the 6 ways that genomes can be altered?

A
  1. Mutations within a gene
  2. Mutations within regulatory DNA - repressor
  3. Gene duplication and divergence
  4. Exon shuffling (swapping genes)
  5. Transposition
  6. Horizontal transfer from other organisms
30
Q

Why does most genetic variation have no phenotypic effect?

A

Falls in intergenic or non-codon region

31
Q

What mechanisms do cells have to prevent and correct mutations?

A

Proofreading by DNA polymerase
Post replication mismatch repair
DNA repair by homologous recombination
Cell cycle checkpoints

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