Nucleic Acid Structure and Function

Function of DNA (DeoxyriboNucleic Acid)

Contains sections called “genes” that code for proteins.

These genes are what are passed on from parent to offspring.

Structure of DNA Discovered by James Watson (US) and

Francis Crick (UK) in 1954. Described the structure as a “double helix”

The Double Helix A twisted ladder

DNA is easier to view in its unwound shape:

A ladder with split rungs

Nucleotides are the Building Blocks of Nucleic Acids

There are 3 parts of the nucleotide: 5-Carbon (Pentose) Sugar Phosphate Nitrogen base

Nucleotide Structure

Sugar and Phosphate make the sides of the ladder

Nitrogen Bases make up the rungs of the ladder

Nitrogen Bases Broken down into 2 groups:

Double Ring Bases Adenine Guanine

Single Ring Bases Cytosine Thymine

Complementary Bases Complementary: Bases that pair to

form a hydrogen bond A – T G – C

Hydrogen bond

Molecular Structure Besides being twisted, the two strands of

DNA run in opposite directions

A 3-Rung DNA molecule