3. Genetics: Sexual Reproduction & Meiosis

Question 1

What is sexual reproduction and what does it produce

Answer 1

Produces genetically different cells

Mother and father produce gametes (reproductive cells) - gametes contain half number of chromosomes - haploid
At fertilisation - male gamete fuses with female gamete - produces fertilised egg - zygote - diploid
Zygote undergoes cell division- mitosis and develops into an embryo

Question 2

How are gametes produced by meosis

Answer 2

Meosis - type of cell division - doesn’t produce genetically identical daughter cells - only happens in testes and ovaries

Division 1 : before cells divide - it duplicates its DNA
Chromosomes line up in pairs in the centre of the cell - one in each pair from the father and the mother
Pairs then pulled apart - some of the fathers chromosomes and some of the mothers chromosomes go into each new cell
The new cells will have mixture of mothers and fathers chromosomes - genetic variation in the offspring

Division 2 : chromosomes line up again in the centre - arms of chromosomes pulled apart - four haploid daughter cells - the gametes - only has single set of chromosomes - gametes are genetically different