Nucleic Acids

- Phosphate group

-Pentose sugar (Deoxyribose in DNA, Ribose in RNA)

-Nitrogenous base (Purines & Pyrimidines)

Phosphodiester bond

The bond holding the third phosphate molecule is broken down by a hydrolysis reaction.

This is catalysed by the enzyme ATPase, producing ADP and a free phosphate molecule.

- Double stranded polynucleotide

- Strands run antiparallel

- The 2 strands are joined together by Hydrogen bonds between bases

- Bases pair by complementary base pairing

- Purine pairs with Pyrimidine

- The molecule is twisted into a double helix

It is a triplet code where a triplet of bases codes for one amino acid

- Degenerate

- Universal

- Non-overlapping

Some amino acids are coded for by more than one triplet of bases.

Each base is only read once.

The same code is used by all living organisms

1. the 2 original strands are separated by the enzyme DNA Helicase. This breaks the H bonds.

2. Each strand now acts as a template for the formation of a new strand.

3. Free DNA nucleotides join up to exposed bases by complementary base pairing.

4. Replication takes place in a 5' to 3' direction and is catalysed by the enyme DNA Polymerase.

5. The new strand is joined to the old strand (semi-conservative) by DNA Ligase.

Each new molecule of DNA has one 'new' strand and one 'old' strand.

- Single stranded polynucleotide

- Ribose replace Deoxyribose as the pentose sugar

- Uracil replaces Thymine

- mRNA: formed in the nucleus. Single chain involved in protein synthesis.

- tRNA: 3 bases make up the anticodon which determine the amino acid that will attach to the tRNA. Involved in protein synthesis.

- rRNA: made in the nucleolus.