B4 - Sexual Reproduction And Meiosis Flashcards
Why are offspring genetically different to either parent?
Genetic information from two organisms is combined to produce offspring
What are gametes?
Father and mother produce gametes.
In animals these are sperm and egg.
What do gametes contain?
Half the number of chromosomes of normal cells.
What happens at fertilisation ?
The male gamete fuses with the female gamete to produce a fertilised egg called a zygote.
What is a zygote?
A fertilised egg
How does the zygote end up with the full set of chromosomes?
The chromosomes from the mother pair up with the chromosomes from the father.
How does an embryo develop?
The zygote undergoes cell division by mitosis.
Where does the embryo inherit characteristics from?
From both parents as its received a mixture of chromosomes (and therefore genes) from both parents.
What is meiosis?
A type of cell division.
Where does meiosis occur in humans?
In the reproductive organs (ovaries and testes)
What has to happen before meiosis?
Interphase.
What happens during the interphase?
The cell grows and duplicates it DNA
When the DNA is duplicated what is produced?
X shaped chromosome, each arm is an exact copy of the other arm.
How many cell divisions are there in meiosis?
Two
What happens during the first division in meiosis?
The chromosomes lineup in pairs in the centre of the cell.(one chromosome in each pair comes from each parent)
The pairs are pulled apart.
