Molecular Genetics

DNA PhenotypeRNA

TranscriptionTranslation

Genome Gene

The flow of information:1. Storage

3. Gene Expression

Protein

2. Replication

Flow of Genetic Information

Flow of Genetic Information

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

Translation

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 Start

codon

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

A mutation is any change in the nucleotide sequence of DNA.–Mutations can change the amino acids in a protein.–Mutations can involve:• Large regions of a chromosome • Just a single nucleotide pair

Mutations

Normal hemoglobin DNA

mRNA

Normal hemoglobin

Mutant hemoglobin DNA

mRNA

Sickle-cell hemoglobin

Mutations