Principles of Biology Lecture Notes Fall, 2006
FROM GENE TO PROTEIN
From Gene to Protein- Outline
211F06 Gene to Protein Lecture Notes.doc 11/10/2006
The Central Dogma:
DNA RNA PROTEIN
TRANSCRIPTION TRANSLATION
Transcription
Initiation
Promoter
Transcription Factors
Elongation
Termination
Product:
Prokaryote: mRNA
Eukaryote: Transcript
Transcript Processing
Capping
Splicing Gene Exon = Protein Domain
Translation: Nucleotide Sequence to AA Sequence
Genetic Code
Initiation
Elongation
Termination
Post-Translation Modification of Polypeptide
Targeting
Folding
Mutation
Types
Effects
211F06 Gene to Protein Lecture Notes.doc 11/10/2006
211F06 Gene to Protein Lecture Notes.doc 11/10/2006
Basic Principles of Transcription and Translation
• Transcription
• Translation
• In prokaryotes
• In eukaryotes
Transcription: Synthesis of an RNA Transcript
• Stages:
– 1.Initiation
– 2.Elongation:
• RNA pol
pries the DNA strands apart
hooks together the RNA nucleotides
– 3. Termination
RNA Polymerase Binding and Initiation of Transcription
• Promoters
•
• Transcription factors
Elongation of the RNA Strand
Termination of Transcription
RNA Processing
Modify Transcript to form mRNA
Cap & polyA Tail
Splicing Remove introns & join exons
Proteins often have a modular architecture: Different exons => different domains
Splicing: Evolutionary Significance
– Consisting of discrete structural and functional regions called domains
– in a protein
Translation
• The basic concept
• Three phases:
– Initiation
– Elongation
– Termination
–
Translation: Nucleotide Sequence to Amino Acid Sequence
• Transcription
Translation
The Genetic Code
• mRNAcodon
tRNA
– specific amino acid
– specific anticodon
–
Ribosomes
– tRNA anticodons with mRNA codons Form peptide bond between amino acids
– 3 Binding sites for tRNA: A, P & E
Building a Polypeptide
Translation three stages Initiation Elongation Termination
Ribosome Association and Initiation of Translation
Elongation of the Polypeptide Chain
Termination of Translation
Completing and Targeting the Functional Protein
Two populations of ribosomes in cells
• Free ribosomes in the cytosol
•
• Ribosomes bound to ER membrane
• Mutations
Point mutations
Two general categories
Spontaneous mutations: Can occur during DNA replication, recombination, or repair
Mutagens: physical or chemical agents that can cause mutations
211F06 Gene to Protein Lecture Notes.doc 11/10/2006