Genes, Chromosomes, Cell division and variation

DNA is the instructions for building all proteins for an organism, it controls the cells functions etc.

DeoxyriboNucleic Acid

It’s in a double helix shape. These strands which form the double helix are phosphate and ribose, which form the backbone of the DNA. It’s also made up of four building blocks, which come in pairs: A-T and C-G, these are a.k.a base pairs. There are many of these in a DNA structure

They instruct the sequence of amino acids in a protein, like an enzyme.

A gene is a length of DNA which codes for a protein

They control chemical reactions, growth, colouration and all inheritab;e characteristics e.g. hieght

3 bases

A rod which comes in pairs (unless it’s a gamete) which carries DNA. It’s made up of DNA and histones

One form father, one form mother. There’s a pair of genes in each nucleus, as genes controlling a specific characteristics are situated at the same point on each homogolous chromosome

23 pairs

Diploid cells, haploid cells only contain 23

Gamete cells e.g. sperm and ovum

Two genetically identical daughter cells produced, involves on e division of a cell, it produces diploid cells acorss the body and keeps the same number of chromosomes in the cell. It occurs throughout a human.

Produces four non identical daughter cells, involves two cell divisions and produces haploid cells in humans. It’s only used to produce gametes.

The difference between individuals from the same parents. It’s important for evolution to occur.

genetic, environmental or both or both

A change in the DNA

Neutral (most common), most sequence mutations result in this. Negative effect (most chromosonial mutations) or positive.

Chemicals which cause more frequent mutations, like antibiotics, UV or radioactivity