Last updated: 30/01/12
Additional Unit 2 Revision
B5 Growth & Development…read more

Genes
What exactly are genes ?
How do they control what goes on in a cell ?
How are they copied so they can get inherited ?…read more

It was known that the nucleus
nucleus contained the material that
controlled the function of the cell
and that this material was inherited.
This genetic material is
made up of structures
called chromosomes.
Chromosomes are made up of a chemical called deoxyribonucleic acid
otherwise known as DNA…read more

DNA is made up of 4 types of nucleic acid called bases.
you don't have
to remember
the structures
Every sample of DNA analysed showed that there were always equal
numbers of adenine and thyamine molecules and equal numbers of
cytosine and guanine molecules.
It seemed reasonable to conclude that adenine paired up with thymine
and cytosine paired up with guanine.…read more

Watson and Crick proposed that DNA had a double helix structure and
explained how this structure could form the basis of a code.…read more

DNA A-T
G-C…read more