Mitosis is a process where a 'Parent' Cell divides into two identical 'Daughter' Cells, which then divides in two and the process repeats.
Mitosis is also the way old and damaged cells are replaced.
Each cell that is reproduced through Mitosis contains 46 Chromosomes.
Meiosis is used to create Gametes(Sex Cells). The number of chromosomes in these Gametes are half (23) because they are going to be fused with another Gamete, be it an egg or a sperm to create the full 46. It is sometimes called Reduction Division.
Unlike Mitosis, Meiosis creates 4 daughter cells instead of 2.
Gametes can be X or Y
A Section of a Chromosome is a Gene
[Diagram On Back]
A chromosome is an organized structure of DNA and protein found in living cells. It's a coiled DNA. Each part of a Chromosome is called a Gene, these hold different pieces of information for each part of the body, how it looks, works and is controlled.
Chromosomes come in pairs, 23 pairs to be precise, and they are found in the nuclei of most cells.
Chromosomes consist of several thousands of genes. They are units of inheritance, and are used for every aspect of your body. Some genes are inherited off your mother through the egg cell, and some from you father in the sperm cell. These fuse and create a mixture which is why you look like your mother and father.
Homologous Chromosomes And Hetrozygous Organisms
Chromosomes in a homologous pair contain the same type of genes that code the same characteristics, for instance eye colour or hair colour.
Each Different Version Of A Gene Is Called An Allele.
Homologous Pairs have the same Allele in the same place on a chromosome. Also it'll be the same type such as a brown eyed allele.
Hetrozygous Organisms[remember it's an organism not the chromosome itself]
Hetrozygous Organisms have different genes in the same place on a Chromosome. For instance one part of the chromosome has a brown eyed gene and the other part has a blue eyed gene.
Don't confuse Hetrozygous Organisms with it being a
Dominant And Recessive Genes
The characteristic that is going to be expressed depends on which Gene (Allele) is dominant and which is recessive:
Dominant Genes (Alleles)
Dominant Genes are always expressed in a cells Phenotype. Only one copy of the dominant allele needs to be inherited in order for it to be expressed over the recessive gene.
Recessive Genes (Alleles)
Recessive Genes are only expressed in a cell's Phenotype if two copies of it are present. If only one copy is present, its effect is stopped by the dominant gene and the dominant gene.
*Phenotype: The visible signs that the dominant gene causes when it is expressed. --------------------So it is how the DNA will make you if a certain gene is used as the --------------------dominant gene.
Gametes (Sex Cells)
Gametes are sex cells, the egg and the sperm. Each egg and sperm are coded with either an X or a Y.
An egg is always an X.
A sperm is either an X or a Y.
There is a 50-50 chance you will get an X or a Y in a sperm.
are coded with an XX-
1 X from the egg, 1 X from the sperm
are coded with an XY-
1 X from the egg, 1 Y from the sperm