Cell Division In Sexual Reproduction Flashcards
What is the term for sex cells such as ova and sperm?
Gametes
How many chromosomes do gametes have?
23 chromosomes (half that of a normal human cell)
Why do gametes have half of the normal number of chromosomes?
So during sexual intercourse a sex cell for the mother and a sex cell from the father combine and the ending cell will still have the right number of chromosomes
How does meiosis produce variation?
The new cell will have a mixture of 2 sets of chromosomes inherited from both parents.
What is the first step in meiosis?
Before division, a copy of each chromosome is made (23 pairs of 46 chromosomes becomes 46 pairs of 92)
How do the cells in reproductive organs divide?
Meiosis
What is the definition of meiosis?
The two stage process of cell division which reduces the chromosome number of the daughter cells. It is involved in making the sex cells for reproduction
What happens after the chromosomes are duplicated in the first division of meiosis?
The chromosome PAiRS (2 X shaped things) line up in the centre of the cell (46 pairs, 96 chromosomes)
After the chromosomes have lined up what happens next in meiosis?
The PAIRS are pulled apart so each new cell only has one copy of each chromosome, some from the father and some from the mother (random) so two cells are formed in the second division (back to 23 pairs, 46 chromosomes)
What happens fist in the second division of meiosis?
The chromosomes line up in the centre again and the arms of the chromosomes are pulled apart, like in mitosis. This results in four gametes with a single set of chromosomes in it (each cell having only 23 chromosomes, half what they should have)
