T7: Genetics, Populations, Evolution + Ecosystems Flashcards

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1
Q

allele

A

one of the different forms of a gene

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2
Q

genotype

A

the genetic makeup of an organism

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3
Q

homologous chromsomes (pair)

A

a pair of chromosomes (maternal+paternal) that have the same loci in diploid organisms

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4
Q

gene

A

a length of DNA that normally codes for a polypeptide

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5
Q

pedigree charts

A

diagram representations of family trees that show patterns of inheritance
male - square + female - circle , shading means characteristic present in phenotype

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6
Q

epistasis

A

when the allele of one gene affects or masks the expression of another in the organism, two genes interact together to affect the phenotype
e:g agouti mice

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7
Q

linked genes / autosomal linkage

A

two or more genes carried on the same non-sex chromosome, explains why characteristics are often inherited together

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8
Q

homozygous

A

two or more of the same alleles present on both homologous chromosomes

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9
Q

loci

A

the position of a gene on a particular chromosome

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10
Q

phenotype

A

the observable or biochemical characteristics of an organism

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11
Q

recessive

A

an allele only expressed when present with an identical allele

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12
Q

Mendel’s law of independent assortment

A

law that states that each member of a pair of alleles may combine randomly with either of another pair

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13
Q

dihybrid crosses

A

inheritance patterns of two genes

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14
Q

dominant

A

an allele always expressed in the phenotype that masks the expression of other alleles

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15
Q

multiple alleles

A

a gene with more than two allelic forms

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16
Q

chi squared

A

stats test that compares observed data with expected ratios

17
Q

null hypothesis

A

there is no significant difference between observed and expected values

if Mendel’s law applies then

18
Q

sex linked

A

a gene that is carried on both the X or Y chromosome

19
Q

co-dominant

A

two alleles are both expressed in the phenotype

20
Q

what do genetic diagrams look like?

A

must contain (F1 ) parent phenotype, parent genotype, gametes and punnet square

21
Q

4 conditions of Hardy weinberg?

A

Large population
No immigration or emigration
No mutations
No natural selection

22
Q

Formula for Hardy weinberg

A

P2+2pq+q2

P = homozygous dominant
2pq = heterozygous
Q = homozygous recessive

23
Q

Explain how natural selection occurs

A

Variation occurs due to mutations giving rise to new alleles
Selection pressure = struggle for survival
Some organisms have alleles that provide are advantageous so are more likely to survive and reproduce
They pass on their advantageous alleles to their offspring
The allele frequency in population increases over time

24
Q

Directional selection

A

Selective pressures favour individuals with a favourable combination of alleles one direction from the mean
Mean shifts in direction of phenotype

25
Q

Stabilising selection

A

Selective pressures favour the mean
Individuals with extreme phenotypes less likely to survive so SD gets smaller over time

26
Q

Disruptive selection

A

Selection against the mean
Favours both extremes of phenotypes
Could result in 2 separate species

27
Q

Speciation

A

Formation of a new species from an existing species

Reproductive separation of 2 populations can result in the accumulation of differences in their gene pools, new species arise when these 2 populations cant interbreed to produce fertile offspring

28
Q

Allopatric speciation

A

Geographical isolation separates the gene pools, no gene flow
Then evolution by natural selection occurs resulting in 2 species that can’t interbreed to produce fertile offspring

29
Q

Sympatric speciation

A

Populations in the same area

30
Q

Genetic drift

A

Allele frequencies change in a population due to chance factors
Stronger in small populations due to chance having a larger effect