✅9 - Genetic Diversity Flashcards

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1
Q

What is a mutation?

A

A change to the base sequence of DNA

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2
Q

What is substitution?

A

When one nucleotide is exchanged for another

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3
Q

What does the significance of a substitution mutation depend on?

A

The importance of the original amino acid

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4
Q

How can a substitution affect the amino acid sequence?

A

If the codon is altered to code for a different amino acid, then the sequence will be altered and the polypeptide changed

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5
Q

What is a deletion mutation?

A

When a nucleotide is lost from the normal DNA sequence

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6
Q

What can deletion cause?

A

Frame shift

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7
Q

What are chromosome mutations?

A

Changes in the structure or number of whole chromosomes

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8
Q

What are the two forms of chromosome mutation?

A

Changes in whole sets of chromosomes

Changes in the number of individual chromosomes

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9
Q

When do changes in whole sets of chromosomes occur?

A

When organisms have three or more sets of chromosomes rather than the usual two, called polyploidy

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10
Q

When do changes in the number of individual chromosomes occur?

A

When chromosomes fail to separate in meiosis, and organisms get one more or one less chromsome

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11
Q

What is mitosis?

A

Produces two daughter cells with the same number of chromosomes as the parent cell and as each other

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12
Q

What is meiosis?

A

Usually produces four daughter cells. each with half the number of chromosomes as the parent cell

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13
Q

Why is meiosis important?

A

Otherwise the number of chromosomes would double each time the gametes fused

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14
Q

What happens in the first division of mitosis?

A

The homologus chromosomes pair up and their chromatids wrap around each other - crossing over may occur

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15
Q

What happens in the second division of meiosis?

A

The chromatids move apart and four cells form

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16
Q

How does meiosis being about genetic variation?

A

Independent segregation of homologus chromosomes

Crossing over

17
Q

How does independent segregation occur?

A

The chromosomes arrange themselves randomly as they line up and which of each pair goes into the daughter cell depends on how they are lined up

18
Q

How does crossing over occur?

A

The chromosomes become twisted around each other and tensions are created, causing portions to break off. These portions may rejoin with the chromatids of the homologus partner, creating new genetic combinations

19
Q

What is genetic diversity?

A

The total number of different alleles in a population

20
Q

What is allelic frequency?

A

The relative frequency of an allele in a population

21
Q

What is selection?

A

The process by which organisms that are better adapted to their environment tend to survive and breed

22
Q

What is directional selection?

A

Favouring alleles to one side of the mean, phenotypes to one extreme

23
Q

What is an example of directional selection?

A

Antibiotic resistance of bacteria

24
Q

What is stabilising selection?

A

Favouring phenotypes around the mean, eliminating extremes

25
Q

What is an example of stabilising selection?

A

Birthweight of babies

26
Q

What are anatomical adaptions to the environment?

A

Shorter ears and thicker fur in arctic foxes

27
Q

What are physiological adaptions to the environment?

A

Oxidising of fat rather than carbohydrates in kangaroo rats to product additional water in dry areas

28
Q

What are behavioural adaptions to the environment?

A

Autumn migration of swallows from the UK to Africa