Topic 8 Origins Of Genetic Variation Flashcards

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1
Q

what are three genetic reasons for genetic variation?

A
  • mutations
  • random independent assortment
  • random fertilisation
  • crossing over in meiosis
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2
Q

what are two types of mutations?

A
  • point mutation (change in bases)
  • chromosome mutation
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3
Q

what are 3 types of point mutations?

A
  • deletion
  • insertion
  • substitution
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4
Q

why do point mutations happen?

A
  • random
  • mutagens increase rate of mutations (eg chemicals, radiation)
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5
Q

who is affected by somatic cell mutations?

A

only the individual

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6
Q

who is affected by gamete mutations?

A

generations to come, passed onto offspring

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7
Q

when does independent assortment happen during meiosis?

A

metaphase I and II

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8
Q

when does crossing over happen during meiosis?

A

prophase I

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9
Q

what are two types of chromosome mutations?

A
  • translocation
  • non disjunction
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10
Q

what is translocation mutation?

A

when a chromosome breaks off and joins a non-homologous chromosome

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11
Q

what is non-disjunction mutation?

A

when a homologous pair fail to separate correctly, some gametes have abnormal number of chromosomes

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12
Q

what are two types of non-disjunction?

A

monosomy and polysomy

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13
Q

what is an example syndrome of monosomy?

A

Turner’s syndrome

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14
Q

what is an example syndrome of polysomy?

A

Down’s syndrome

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15
Q

what is the chi squared equation?

A

(O-E)^2
———– (divide by)
2

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16
Q

What is the definition of polygenic? 2 marks

A
  • A characteristic influenced by 2 or more genes (1)
  • in different loci (1)
  • common to see variation in traits (eg hair colour)
17
Q

Justify why xxx is a recessive condition - 3 marks

A
  • 2 recessive alleles are needed to have X condition
  • individuals A and B do not have X but some of their children do
  • therefore A and B must be heterozygous
18
Q

What is the definition of a gene pool

A

total number of genes of every individual in a population

19
Q

what are allele frequencies?

A

proportion of each allele within a gene pool

20
Q

what are 2 types of selection?

A
  • stabilising
  • disruptive
    (- directional)
21
Q

what is transient polymorphism?

A

selective advantages changes overtime (disruptive selection)

22
Q

2 factors that can influence allele frequencies in a population:

A
  • founder effect
  • genetic bottlenecks
  • genetic drift
23
Q

what is a genetic drift?

A

changes in gene pool bcs of random selection of alleles

24
Q

what is the founder effect?

A

when small groups of individuals leave a larger pop and develop new isolated pop
- alleles in offspring are determined by the founders

25
Q

what are population bottlenecks?

A

when entire species are wiped out except for a small group of survivors
so numbers and diversity fall dramatically

26
Q

what is the hardy weinberg equation and what do they stand for?

A

p^2 + 2pq + q^2 = 1
p^2 = homozygous dominant
q^2 = homozygous recessive
2pq = heterozygous
p + q = 1
p= dominant ALLELE
q= recessive ALLELE

27
Q

in chi squared hypothesis testing, when do we accept or reject H0?

A

when calculated chi2 value > value on table (n-1, 0.05), reject H0.

28
Q

How does inbreeding cause genetic defects? (2 marks)

A

Reduced gene pool
Increasing chance of homologous recessive genotypes for genetic defects

29
Q

What is a gene locus? 2 marks

A

Where the allele is located on a chromosome

30
Q

What are conditions for the Hardy-Weinberg equation?

A
  • no mutations
  • random mating
  • large population
  • no selection pressures