B1.14 Causes Of Genetic Variation

Question 1

What causes genetic variation?

Answer 1

Mutations
Formations of gametes
Fertilisation

Question 2

How does mutation change genes?

Answer 2

Changes the structure of a gene- a mistake happens when DNA is being copied before cells divide

Question 3

What are alleles?

Answer 3

A mutation may change a gene to a different version, called an allele. It codes for thesame characteristic but will produce a slightly different version of the characteristic

Question 4

What else can causes genetic variation?

Answer 4

Sexual reproduction (involves fertilisation)

Question 5

What are gametes?

Answer 5

Gametes are special sex spcells. They contain only 23 chromoomes. (1/2)

• female gametes are eggs
• male gametes are sperm

Question 6

How are gametes made?

Answer 6

Made from body cells by a special type of cell division.
Body cells- 23 pairs of chromosomes
Pairs seperate during cell division

Question 7

How does gamete formation produce genetic variation?

Answer 7

• during cell division, pairs of chromosomes may swap with each other, giving them different combinations of alleles but still have the same gene
• two copes of each chromosome seperate from each other dueing the second meiotic division is random

Question 8

How does fertilsition occur?

Answer 8

A male and female gamete join by fertilisation to make a new individual.

Fertilisation is random and produces genetic variation.

Each egg produced by the mother is geneticqlly different from the other eggs she makes.

Sperm joins with the egg. Each individual is unique.

Question 9

Explain the male gamete and female gamete coming together.

Answer 9

One male gamete (sperm) and one female gamete (egg) fuse. Results in fertilised eggs which will become a new individual contains the full number of chromosomes.

1/2 from mother, 1/2 from father

Mixture of genetic info from 2 pare ts leads to genetic variatio s in the offspring