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Genetics and Evolution > Genetic Variation > Flashcards

Genetic Variation Flashcards

1
Q

What is genetic variation?

A

Differences (variations) in DNA sequence between individuals within a population

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2
Q

What percentage of the genome differs between individuals in the human population?

A

0.1%

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3
Q

How many alleles does one gene loci consist of?

A

Two alleles

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4
Q

What are homozygous alleles?

A

The same alleles (AA or aa)

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5
Q

What are heterozygous alleles?

A

Different alleles (Aa)

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6
Q

Genetic variation in populations is due to what property of alleles?

A

Heterozygosity

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7
Q

What is inherited (constitutional) genetic variation?

A

Genetic variants are inherited from the parents. The alleles must be in the gremlin

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8
Q

What are some examples of inherited (constitutional) genetic variation?

A

Eye colour and blood type

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9
Q

What is somatic (post-zygotic) genetic variation?

A

These are DNA changes acquired from the zygote stage and onwards throughout life

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10
Q

DNA variants are passed through cellular progeny by what process in post-zygotic genetic variation?

A

Mitosis

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11
Q

DNA sequence variation is caused by what?

A

Mutations

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12
Q

What are the three types of small scale mutations?

A
  1. Single nucleotide substitutions
  2. Insertions
  3. Deletions
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13
Q

What is a silent mutation?

A

A mutation that does not cause a change in the amino acid during translation

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14
Q

What is a missense mutation?

A

A mutation that causes a change in the amino acid during translation

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15
Q

What is a nonsense mutation?

A

A mutation that codes for a stop codon instead of an amino acid - this truncates the protein

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16
Q

What is the cause of a frameshift mutation?

A

Insertions or deletions

17
Q

What is the most common type of genetic variation in humans?

A

Single nucleotide substitution

18
Q

What is a single nucleotide polymorphism (SNP)?

A

It is a mutation/genetic variation that is only found in less than 1% of the population

19
Q

Single nucleotide polymorphisms (SNPs) are usually inherited in multiple, closely located blocks on a chromosome. What are these blocks called?

A

Haplotype blocks

20
Q

Are mutations in a gene always pathological?

A

No, because mutations may not always change the function product of a gene. They could occur in an intron or a 3rd base position within a codon

21
Q

Why is genetic variation important for evolution?

A

Genetic variation may provide beneficial changes in phenotypes, which are then naturally selected for. This enables individuals to adapt to changes in the environment

22
Q

Sickle cell disease is caused by a single nucleotide substitution in what base position of a codon?

A

The 2nd base

23
Q

What is ischaemia?

A

A lack of oxygen delivery

24
Q

Heterozygote carriers of sickle cell disease confer some resistance to what other disease?

A

Malaria

25
Q

Insertions or deletions are very common in areas of DNA containing what?

A

Repetitions of a single nucleotide or tandem repeats of short sequences

26
Q

Inserting or deleting bases causes a frameshift. What can this cause in terms of the amino acids?

A
  1. Frameshift causing extensive missense
  2. Frameshift causing nonsense
27
Q

Cystic Fibrosis is caused by a deletion mutation. In what protein does this occur?

A

The Cystic Fibrosis transmembrane conductance regulator (CFTR) protein

28
Q

What are splice variants?

A

Mutations that occur in donor/acceptor sites at exon-intron boundaries which prevent the Spliceosome splicing out relevant sequences

29
Q

What is the donor site at exon-intron boundaries?

A

GU

30
Q

What is the acceptor site at exon-intron boundaries?

A

AG

31
Q

Short tandem repeats are usually less than six base pairs in length. They are hotspots for what types of genetic variation?

A
  1. Replication slippage
  2. Frequent causes of insertions and deletions (indels)
32
Q

Variable number tandem repeats are much longer and variable in number of repeats. How can they be useful in genetic science due to their variability?

A

They can be used in forensics & parental identification

33
Q

Huntington’s disease is a progressive brain disorder that is caused by tandem repeats of what three bases in the HTT gene?

A

CAG

34
Q

What is meant by an ‘autosomal dominant condition’?

A

Only one affected allele needs to be carried on a gene loci for the condition to be presented

35
Q

What are translocations?

A

The exchange of genetic material between chromosomes

36
Q

Reciprocal translocations are the exchange of genetic material between what type of chromosomes?

A

Non-homologous

37
Q

What is aneuploidy?

A

An abnormal amount of chromosomes in a cell

38
Q

What type of condition is caused by meiotic nondisjunction?

A

Down’s syndrome

Genetics and Evolution (14 decks)

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