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Biology
PSHE / Citizenship studies
Science (applied)
Biology
PSHE / Citizenship studies
Biology
PSHE / Citizenship studies
Science (applied)
Biology
Biology
Meiosis is the process by which new cells with half the usual number of chromosomechromosome
A chromosome is like a packet of coiled up DNA. Humans have 23 pairs of chromosomes. They are in the nucleus of every human cell.
s are produced. In humans the full complement of 46 chromosomes is called the diploiddiploid
Have two sets of paired chromosomes.
number. Meiosis produces cells with 23 chromosomes, known as the haploidhaploid
Have a single set of chromosomes.
number, and these are the gametegamete
The sex cells (ovum and sperm) that join together to form a new unique diploid cell in sexual reproduction.
s, i.e. sperms for males and ova for females.
In meiosis there are two lots of cell divisioncell division
The process by which a parent cell divides into two daughter cells.
so that a single diploiddiploid
Have two sets of paired chromosomes.
cell gives rise to four haploidhaploid
Have a single set of chromosomes.
cells. During fertilisation two haploid nuclei join to give a zygotezygote
A fertilised cell produced as the result of the combination of an ovum and a sperm.
with the diploid numberdiploid number
The number of chromosomes in most ordinary body cells. In humans this number is 46.
of chromosomechromosome
A chromosome is like a packet of coiled up DNA. Humans have 23 pairs of chromosomes. They are in the nucleus of every human cell.
s. The zygote then grows and develops by mitosis.
Many characteristics are controlled by a gene (or sometimes a few genes). The gender of the next generation, however, is determined by a whole chromosomechromosome
A chromosome is like a packet of coiled up DNA. Humans have 23 pairs of chromosomes. They are in the nucleus of every human cell.
. Human chromosome pair number 23 differs between male and female. It can be XX, which is female, or XY, which is male. In the following genetic diagramgenetic diagram
A diagram to represent the alleles and gametes present for a particular characteristic in parents and the possible allele combinations in their children.
, the letters represent chromosomes.
It shows that the ratio of boys to girls is 1:1, that is, there is always an equal chance of getting a boy and a girl.