gentic diversity- mutations, meiosis Flashcards

1
Q

what is genetic diversity

A
  • the total number of different alleles in a population
  • the greater number of alleles that all members of a species possess, the greater genetic diversity
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2
Q

gene mutation

A

a change to one or more nucleotide bases, or a change in the sequence of the bases within a gene

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3
Q

chromosome mutation

A

a change in the structure or number of whole chromosomes

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4
Q

in which cells would a mutation have to occur in order to be inherited

A

gametes/ cells producing gametes

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5
Q

factors that cause mutations

A

spontaneous
radiation
chemicals biological agents

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6
Q

what do we call something that increases the rate of mutations

A

mutagenic agent

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7
Q

gene mutation types

A

deletion and insertion of bases
substitution

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8
Q

which type of mutation causes a frame shift

A

deletion and insertion

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9
Q

example of a genetic disease caused by substitution mutation

A

sickle cell anaemia

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10
Q

why might a substitution mutation not cause any change to the amino acid in a polypeptide

A

the code is degenerate
may result in a trip,et which codes for the amino acid

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11
Q

chromosome mutations

A

changes in the structure or number of whole chromosomes

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12
Q

polyploidy

A

where organisms have three or more whole sets of chromosomes
commonly seen in plants

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13
Q

non disjunction

A

when individual homologous pairs fail to separate during meiosis
resulting gamete either has one more or one fewer chromosome

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14
Q

what does the process of mitosis result in

A

2 daughter cells
genetically identical
same number of chromosomes
often diploid

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15
Q

what does meiosis result in

A

4 daughter cells
genetically different
half the number of chromosomes
haploid
gametes

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16
Q

meiosis brings out genetic variation due to

A

crossing over - new combinations of maternal and paternal alleles
independent segregation of homologous chromosomes

17
Q

diploid

A

chromosomes occur in homologous pairs

18
Q

what are homologous chromosomes

A

two chromosomes carrying the same genes
chromosomes may carry different allele of the genes

19
Q

allele

A

alternative form of a gene

20
Q

the first division of meiosis

A

division 1
separates the homologous chromosomes

21
Q

prophase 1

A
22
Q

prophase 1

A

chromosomes coil up and become visible
spindle fibres form
nuclear membrane and nucleolus disappear
homologous chromosomes pair up- synapsis
chromatids of the homologous warp around each other many times- crossing over
portions of the chromatids break off and re join with the chromatids on the homologous chromosome- recombination
the points where this exchange of genetic material takes place are called chiasmata

23
Q

metaphase 1

A

homologous pairs of chromosomes line up on the equator of the cell
chromosomes of each pair orientating randomly either side- independent segregation

24
Q

anaphase 1

A

one of each homologous pair moves to each pole

25
Q

telophase 1

A

two daughter cells form each containing only one pair of homologous chromosomes

26
Q

the second division
meiosis 2

A

separates the chromatids

27
Q

population

A

group of individuals of the same species that live in the same place and can interbreed to produce fertile offspring

28
Q

gene pool

A

all of the alleles that exist in a population at a specific time

29
Q

allele frequency

A

the number of times an allele appears within a populations gene pool
allele of interest/total number of alleles

30
Q

natural selection

A
  1. random mutation, new allele, advantage, variation
  2. increased survival
  3. pass advantageous alleles to next generation, increased reproductive success
  4. next generation will have advantageous allele, survive and reproduce
  5. frequency of the advantageous allele in the gene pool will increase
31
Q

selection

A

organisms that are better adapted to their environment survive and reproduce

32
Q

phenotype

A

the physical and chemical characteristics of an organism

33
Q

directional selection

A

selection for a particular characteristic may favor individuals that vary in one direction away from the mean of the original population

34
Q

how would a mutation make the bacterium resistant to penicillin

A

new protein was an enzyme called penicillinase that hydrolysed the penicillin before it was able to kill the bacteria

35
Q

how does stabilising selection affect the genetic diversity of a population

A

less diverse- phenotypes at the extremes are eliminated