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