Introduction• To produce a protein:

– Assemble amino acid – polypeptide chains – DNA contains the necessary information

• DNA makes up chromosomes – Chromosomes contain genes – Chromosomes do not leave the nucleus

• Protein synthesis occurs on the surface of the ribosomes

• Problem: How does the cell get the information to build a protein to the ribosomes?

Transcription • How is the language

of DNA made available to the ribosomes to produce proteins?

• DNA – genes are copied into mRNA – RNA differs from DNA – Adenine bonds with

Uracil– “m” – messenger

• Animation• Animation II

mRNA and Transcription• Transcription factors

loosen DNA histone proteins and bind to promoter

• DNA strand to be copied – “template”

• RNA-polymerase assembles nucleotides

• RNA is processed – Pre-RNA– Exons: coding sections– Introns: non-coding

sections spliced out

Translation • mRNA language is

“translated” into the language of amino acids.

• mRNA triplet sections – Codon codes for one amino

acid– Assembled on the ribosomes

• tRNA – “transfer RNA” – Base pairs with the mRNA

codon – Brings correct amino acid to

the ribosome surface

The Genetic Code • Codons base pair

with anti-codons on tRNA

• Complete this mRNA segment: GGC CGA UUU

• To identify the correct amino acid use the genetic code

Forming a polypeptide chain • Amino acids are assembled via peptide

bonding

Protein Synthesis • Animation