Protein Synthesis
Proteins Most diverse macromolecule Shape = function Responsible for many different functions – Structure – Signal – Enzyme – Defense – Motility
Archibald Garrod Studied alkaptonuria Inherited trait Mutation in enzyme Concluded gene responsible for enzyme
George Beadle and Edward Tatum Studied neurospora X-ray caused random mutations in genes Neurospora did not grow – Additional nutrients required Concluded one gene-one enzyme hypothesis – Later expanded one gene-one polypeptide hypothesis
Central Dogma
Transcription DNA → RNA Occurs in nucleus Why is this step needed? Why not DNA to protein directly?
DNA vs. RNA DNARNA (mRNA, tRNA, rRNA) Double strandSingle strand ThymineUracil Deoxyribose sugarRibose sugar Within nucleusWithin cell
RNA Messenger RNA (mRNA) – RNA version of DNA – Varies in length – Translated into protein Transfer RNA (tRNA) – Delivery system of amino acids – base pairs Ribosomal RNA (rRNA) – Structural component of ribosome – Binds with proteins to form ribosomes – Varies in length
Translation RNA → polypeptide Occurs in cytosol Involves mRNA, tRNA, and rRNA
Genetic Code 4 bases, 20 amino acids…how? Codon: group of three base pairs – How many codons? – Each codon represents an amino acid or start/stop
Homework Page 318 # 3, 4, 7, 8, 11