DNA Deoxyribonucleic Acid
What are the building blocks of DNA? • DNA is an organic macromolecule. • It contains the genetic blueprint in life • Shape is described as a double helix (twisted ladder). • The sides of the ladder are made up of deoxyribose (a sugar) and phosphate. • The rungs of the ladder are composed of nitrogen bases. • A nucleotide consists of a sugar, phosphate and a base.
What is the Base-Pair Rule? • Nucleotides contain four nitrogenous bases: Adenine (A), Thymine (T), Guanine (G), Cytosine (C) • Nitrogenous bases pair in a specific way called the Base-Pair Rule • Adenine (purine) pairs to Thymine (pyrimidine) • Guanine (purine) pairs to Cytosine (pyrimidine)
How does DNA replicate? • DNA replication occurs during the S phase of Interphase when DNA is duplicated. • DNA polymerases (enzymes) bond incoming nucleotides to form a new DNA strand. • Replication begins at origins of replication and moves out from both sides. • DNA conserves itself because each replicated strand contains half of an old one and half of a new one.