Meiosis halves the number
Diploid to haploid.
46 to 23
A human body cell has 46 chromosomes, but a human sperm or egg has only 23.
What do you think happens to the chromosome number when sperm and eggs are made?
What this lesson covers
The idea
Meiosis is cell division that forms gametes: the chromosomes of each pair separate, so the diploid chromosome number of the parent cell is halved to haploid, each gamete receiving one chromosome of every pair.
46 to 23
A human body cell has 46 chromosomes, but a human sperm or egg has only 23.
What do you think happens to the chromosome number when sperm and eggs are made?
- It is cut to half
- It stays the same
- It doubles
Pairs separate
Press Next step to follow the chromosomes in the picture (2 pairs only, as an example).
Half, one of each pair
In the picture the pairs separated, and each gamete got one chromosome from each pair. So 4 chromosomes became 2.
Meiosis is cell division that forms gametes. The chromosomes of each pair separate, so the diploid chromosome number of the parent cell is halved to haploid, each gamete receiving one chromosome of every pair.
Notes
Meiosis separates each pair, so the diploid number is halved to haploid: each gamete gets one chromosome of every pair.
Check yourself
A human body cell has 46 chromosomes. How many chromosomes does a human gamete have?
Answer: 23
Meiosis halves 46, so a gamete has 23.
Meiosis is the cell division that forms…
In an example, a cell has 8 chromosomes in 4 pairs. How many chromosomes does each gamete get?
Answer: 4
One from each of the 4 pairs, so 4 chromosomes.
In meiosis, what happens to the chromosomes of each pair?
- clones. Clones are formed by mitosis in asexual reproduction.
- buds. Buds form by repeated cell division in organisms like hydra.
- gametes — correct. Yes!
- They separate — correct. Yes!
- They join into one. The chromosomes of each pair separate, so each gamete receives one of them.
- They are all lost. Each gamete receives one chromosome from each pair, so none are lost.