1. Meiosis and Genetic Variation Flashcards

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1
Q

Most cells in the body contain exactly the same genetic information except which cell?

A

The gametes - cells involved in sexual reproduction.

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2
Q

Define diploid.

A

When a cell contains 2 copies of each chromosome.

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3
Q

What do normal body cells contain?

A

Diploid number of chromosomes.

Meaning each cell contains 2 of each chromosomes, one from mum and one from dad.

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4
Q

What is the other way to write diploid number?

A

2n.

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5
Q

The chromosomes that make up each pair have what in common?

A

Same size and have the same genes.
BUT.
They could have different versions if those genes - alleles.

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6
Q

Define allele.

A

Alternative form of gene.

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7
Q

Define gene.

A

A section of DNA which codes for a protein.

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8
Q

What are pairs of matching chromosomes called?

A

Homologous pairs.

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9
Q

Define homologous pair.

A

A pair of matching chromosomes containing the same genes but could have different alleles.

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10
Q

How many homologous pairs of chromosomes do humans have?

A

23 pairs, so 46 chromosomes in total.

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11
Q

What is the diploid number for humans?

A

46.

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12
Q

Define gametes.

A

The sperm cells in males and egg cells in females.

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13
Q

Define haploid.

A

When a cell contains one copy of each chromosome.

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14
Q

How many chromosomes do gametes have?

A

Haploid number.
Only containing one copy of each chromosome in a homologous pair.
Haploid number is 23.

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15
Q

What is the other way to write haploid?

A

n.

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16
Q

What happens during sexual reproduction?

A

2 gametes join together at fertilisation to form a zygote, which divides and develops into a new organism.

17
Q

At fertilisation…

A

A h.
Haploid sperm fuses with a haploid egg, making a cell with the normal diploid number of chromosomes.
Half the chromosomes come from father (sperm) half come from mother (egg).

18
Q

How is fertilisation random?

A

Because any sperm can fertilise any egg.

19
Q

Define zygote.

A

The diploid cell formed when 2 gametes fuse during fertilisation.

20
Q

What does random fertilisation produce?

A

Zygotes with different combinations of chromosomes to both parents.
The mixing of genetic material in sexual reproduction increases genetic diversity within a species.

21
Q

In humans, where does meiosis take place?

A

Ovaries and testes.