ARCH 131 Lecture Notes - Lecture 4: Nitrogenous Base, The Sequence, Guanine

• School: Simon Fraser University
• Department: Archaeology
• Course: ARCH 131
• Professor: Dennis Sandgathe

Document Summary

First life on earth appeared 3. 8 billion years ago called prokaryotic cells. These single cells had genetic material floating inside them. Then eukaryotic cells appeared 1. 5 billion years ago. Mitochondria (energy producing part) has its own dna. Ribosomes: place where protein synthesis takes place. Basic structure of dna (double helix) was discovered by james crick, francis watson and. Dna consists of phosphate joined to a sugar molecules, which is joined to a nitrogenous base. Together they form a neucleotide, the basic unit of dna. The types nitrogenous bases are adenine (a), guanine (g), thymine (t), cytocine (c) A always joing with t and g always joins with c. these are called base pairs. The sequence of base pairs provide coding for amino acids. The sequence of amino acids provide coding for different proteins. A gene is a set sequence of nitrogenous bases (out of whole dna sequence) that code for a specific protein.