Molecular Genetics

DNA PhenotypeRNA

TranscriptionTranslation

Genome Gene

The flow of information:1. Storage

3. Gene Expression

Protein

2. Replication

The Molecular Basis of Heredity

The Flow of Genetic Information in the Cell

The Genetic Code

Transcription

*RNA polymerasereminder: RNA contains ribose, phosphate group and A, C, G and U (not T)

*RNA polymerase (from E. coli )

a2 b b’s *Sigma factor

Core*Core

Sigma factor

Holoenzyme

Initiation of Transcription:

Transcription Overview

RNA Processing in Eukaryotes

Start of geneticmessage

Tail

End

Cap

Translation requires:• Messenger RNA (mRNA)• Transfer RNA (tRNA)• Ribosomes• ATP• Enzymes (translation factors)

Translation

TranslationTransfer RNA (tRNA):

• Molecular interpreter

• Matches amino acids with codons in mRNA using anticodons

Anticodon

Amino acid attachment site

tRNA Structure

tRNA binding sites

LargesubunitSmallsubunit

P site A site

TranslationRibosomes:• Coordinate the functions of mRNA and tRNA• Made of two subunits• Contain ribosomal RNA (rRNA)

InitiatortRNA

mRNA

TranslationComplex formation:

• Ribosome• mRNA• Initiator tRNA• Translation factors

Startcodon

TranslationCodon Recognition:• Another tRNA• Translation factors

InitiatortRNA

mRNA

Startcodon

Anticodon

TranslationPeptide Bond Formation:

TranslationTranslocation:

Newpeptidebond

mRNAmovement

TranslationElongation:

Stopcodon

Translocation

Peptide bond formation

ELONGATION

Codon recognition

Transcription

mRNA DNA

Nucleus

mRNA

RNA processing

Amino acidattachment

EnzymeATP Initiationof translation

Elongation

Termination

Polypeptide

tRNA Charging