Biology Edexcel topic 1 b2 DNA

DNA

its is a DOUBLE HELIX  of PAIRED BASES

a molecule of dna contains two strands held together by CHEMICALS  called bases

the four different bases include;

• ADENINE
• CYTOSINE
• GUANINE
• THYMINE

they are always paired and in the same way e.g A-T G-C by a weak HYDROGEN BOND.

How the structure of DNA was discovered

the 4 scientists involved; 

• watson
• crick
• franklin 
• wilkins

Franklin and Wilkins discovered the HELIX shape by directing beams on to CRYSTALLISED DNA and looking at…