TRANSLATION

Cytoplasm Nucleus DNA Transcription RNA Translation Protein

Genetic Information  The sequence of nucleotides in DNA is a code for a protein (football) –Today: RNA to protein  Translation- switching from nucleotide “language” to amino acid “language”  Specific sequence of 3 nucleotides is a codon Copyright © 2009 Pearson Education, Inc.

Polypeptide Translation Transcription Gene 1 DNA molecule DNA strand Codon Amino acid Gene 2 Gene 3 RNA

Polypeptide Translation Transcription DNA strand Codon Amino acid RNA (Protein)

Characteristics of the genetic code –3 nucleotides = 1 codon = 1 amino acid (AA) 61 codons, 21 amino acids (huh?) Copyright © 2009 Pearson Education, Inc.

First base Third base Second base

Characteristics of the genetic code –AUG = Methionine (start of translation) –3 “stop” codons (end of translation) Copyright © 2009 Pearson Education, Inc.

RNA TO PROTEIN START Threonine Leucine Arginine Serine STOP Glutamate

Transfer RNA molecules serve as interpreters during translation  Transfer RNA (tRNA) molecules match amino acid to corresponding mRNA codon –Translator- speaks both languages –tRNA carries a specific amino acid –An anticodon allows the tRNA to bind to a specific mRNA codon –A/U and G/C Copyright © 2009 Pearson Education, Inc.

Transfer RNA molecules serve as interpreters during translation Copyright © 2009 Pearson Education, Inc.

Ribosomes build proteins –Two subunits: small and large –Subunits together during translation –Binding sites for mRNA and tRNAs Copyright © 2009 Pearson Education, Inc.

tRNA-binding sites Large subunit Small subunit mRNA binding site

mRNA Next amino acid to be added to polypeptide Growing polypeptide Codons tRNA

Start of genetic message End

Small ribosomal subunit Start codon P site mRNA A site Large ribosomal subunit Initiator tRNA Met 2 1

Steps of Translation  Initiation  Elongation  Termination Copyright © 2009 Pearson Education, Inc.

Polypeptide A site 1 Codon recognition Codons Amino acid Anticodon P site mRNA

Polypeptide A site 1 Codon recognition Codons Amino acid Anticodon P site mRNA 2 Peptide bond formation

Polypeptide A site 1 Codon recognition Codons Amino acid Anticodon P site mRNA 2 Peptide bond formation 3 Translocation New peptide bond

Polypeptide A site 1 Codon recognition Codons Amino acid Anticodon P site mRNA 2 Peptide bond formation 3 Translocation New peptide bond Stop codon mRNA movement