Inheritance And Selection Flashcards

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1
Q

What is a genotype?

A

The genetic composition of an organism

All alleles in an organism

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2
Q

What is a phenotype?

A

The characteristics of an organism, often visible, resulting from its genotype and the environment

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3
Q

What is a gene?

A

A section of DNA that is a sequence of nucleotides that determine a singular characteristic
Codes for a specific amino acid

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4
Q

What is an allele?

A

One of the different forms of a gene

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5
Q

What is a dominant allele?

A

An allele that is always expressed in the phenotype

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6
Q

What is a recessive allele?

A

When the allele is only expressed if it is homozygous or diploid as it is masked by the dominant

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7
Q

What are co-dominant alleles?

A

When two alleles are equally dominant and do contribute to the phenotype

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8
Q

What is monohybrid inheritance?

A

The inheritance of a single gene

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9
Q

What are the sex chromosomes for male and female?

A

Male - XY

Female - XX

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10
Q

How are sex linked diseases inherited?

A

For most of the X chromosome there is no equivalent portion of the Y chromosome
Recessive alleles on the non-homologous portion of the X chromosome will appear more frequently in males
Because there is not dominant allele to stop the recessive allele being expressed

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11
Q

In sex linked diseases who is the disease inherited from?

A

A male inherits it from his mother as his father will have a Y chromosome and so cannot pas an allele on
But a father can pass it to a daughter on the X chromosome

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12
Q

What are the blood groups and which ones are recessive or dominant?

A

A - AA or AO
B - BB or BO
AB - AB
O - OO

A and B are co dominant and O is recessive

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13
Q

What five conditions are assumed when calculating Hardy-Weinberg?

A
No mutations
An isolated population
Mating is random
No selection 
The population is large
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14
Q

What does the Hardy-Weinberg principle predict?

A

That the proportion of dominant and recessive alleles of any gene in a population remains the same from one generation to the next

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15
Q

What is directional selection?

A

If the environmental conditions change so that those with phenotype a further away from the mean are more adapted for the new conditions

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16
Q

What is stabilising selection?

A

When environmental conditions stay stable so individuals with phenotypes closer to the mean are favoured

17
Q

What is speciation?

A

The evolution of a new species from existing species

18
Q

Stages of geographical isolation

A

When a physical barrier prevents two populations from breeding
Climate change creates two different conditions, one hot, one cold
Those with advantageous phenotypes survive and breed passing on the allele for it
Others not adapted die
Allele type and frequency in the gene pools become more different until they are different species
They will not be able to breed to produce fertile offspring