B13.2 Cell division in sexual reproduction Flashcards
What does Meiosis result in?
Sex cells called gametes which only half the original number of chromosomes
What is the step by step process of Meiosis?
The chromosome number is reduced by half. In a body cell there 2 sets of each chromosome - one inherited from the mother and one from the father
What is a haploid?
Sex cell that contains one set of chromosomes
Where does meiosis take place?
In reproductive organs
What is the 1st stage of meiosis?
All of the chromosomes are copied so that there are 4 sets of each chromosome instead of the normal 2 sets - forms a chromatids
The cells then divide once
Then again divide again forming the gametes
What does Meiosis produce?
Four gametes from one original cell
How is an embryo formed?
By the zygote dividing by mitosis producing a clump of identical cells
Why are gametes not identical to one another?
Due to each gamete containing random mixtures of the original chromosomes. Introduces variation
What is the parent cell?
A cell that is the source of other cells, as a cell that divides to produce two or more daughter cells
Why is meiosis used?
Production of gametes for sexual reproduction
Why is Mitosis used?
Growth and repair
And is asexual reproduction
How does variation occur during fertilisation?
Combination of genes on the chromosomes of every newly fertilised egg is unique due to the sperm cell and egg cell having unique genes
What happens as the embryo develops?
Cells differentiate to form different tissues organs and organ systems
What is involved in asexual reproduction?
Offspring produced as a result of mitosis from the parent’s cell
Contain the same chromosomes and the genes as their parents - there is no variation
What is involved in sexual reproduction?
Gametes are produced by meiosis in the sex organs of the parents
Introduces variation as each gamete is different
