science revision
Meiosis
What is Meiosis
Mitosis is a type of cell that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus and the ordinary tissue growth.
What do they do?
Is a single cell that divides twice to produce four cells containing genetic information. These cells are our sex cells – sperm in males, eggs in females.
DNA
What does DNA do?
DNA contains the instructions needed for an organism to develop, survive and reproduce. To carry out these functions, DNA sequences must be converted into messages that can be used to produce proteins, which are the complex molecules that do most of the work in our bodies
A molecule of DNA
A Molecule of DNA contains 2 strands, each of which forms a shape called Helix
A strand
2 strands are joined together bye pairs of substances called Bases, to a double Helix
4 bases in a DNA
ADenine, thymine, cytosine, guanine. We call them A.T,C<,G
Variation
Some of the variation is caused by differences in allies.
Some of the variants is caused by the environment affect
Some variations are caused by the allies in the environment.
Environment characteristics
That they have changed by the environment during the life of the individule
Variants can be grouped into 2 types of groups
Continuous is where data can be any value in a range
Discontinus is where data can only take a limited set of values.