Review: The flow of genetic information in the cell is DNARNAprotein

The sequence of codons in DNA spells out the primary structure of a polypeptide Polypeptides form proteins that cells and

organisms use Animation of Translation

TRANSLATION

Figure 10.7

DNA molecule

Gene 1

Gene 2

Gene 3

DNA strand

TRANSCRIPTION

RNA

Polypeptide

TRANSLATIONCodon

Amino acid

Transfer RNA molecules serve as interpreters during translation

In the cytoplasm, a ribosome attaches to the mRNA and translates its message into a polypeptide

The process is aided by transfer RNAs

Figure 10.11A

Hydrogen bond

Amino acid attachment site

RNA polynucleotide chain

Anticodon

Each tRNA molecule has a triplet anticodon on one end and an amino acid attachment site on the other

Figure 10.11B, C

Anticodon

Amino acidattachment site

An exercise in translating the genetic code

Startcodon

RNA

Transcribed strand

StopcodonTranslation

Transcription

DNA

Ribosomes build polypeptides

Figure 10.12A-C

Codons

tRNAmolecules

mRNA

Growingpolypeptide

Largesubunit

Smallsubunit

mRNA

mRNAbindingsite

Growingpolypeptide

tRNA

Next amino acidto be added topolypeptide

Table 14.2Types of RNA

Type of RNA Functions in Function

Messenger RNA(mRNA)

Nucleus, migratesto ribosomesin cytoplasm

Carries DNA sequenceinformation to ribosomes

Transfer RNA(tRNA)

Cytoplasm Provides linkage between mRNAand amino acids;transfers aminoacids to ribosomes

Ribosomal RNA(rRNA)

Cytoplasm Structural component of ribosomes

(continued)

4Stage ElongationGrowingpolypeptide

Codons

5Stage Termination

mRNA

Newpeptidebondforming

Stop Codon

The ribosome recognizes a stop codon. The poly-peptide is terminated and released.

A succession of tRNAs add their amino acids to the polypeptide chain as the mRNA is moved through the ribosome, one codon at a time.

Polypeptide