1.2 - Structure and Replication of DNA

Structure and Replication of DNA

Higher Human Biology 1.2

DNA is present in every living cell, its a molecule that is inherited and contains genetic information in its sequence of bases. 

DNA consists of two strands wrapped in a double helix, made up of nucleotides. Each nucleotide is made with a deoxyribose sugar, base and a phosphate group. Between the phosphates, a strong chemical bond forms and makes the DNA molecule's sugar phosphate backbone. 

DNA has an antiparallel structure. The deoxyribose is at the 3' (3 prime) end and the phosphate is at the 5' (5 prime) end of each strand which forms the double helix.

In DNA, there are four types of base:

• adenine
• thymine
• cytosine
• guanine

The two strands are joined togehter by weak hydrogen bonds between bases. Each base can only pair up with one other base:

• adenine pairs with thymine
• cytosine pairs with guanine

Before cell division…