Protein Synthesis

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Protein Synthesis

• The making of protein

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Overview

• http//learn.genetics.utah.edu/content/begin/dna/f
  irefly/
• Explain what happens

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Protein Synthesis occurs in 2 steps

• Transcription
• Creates mRNA from code contained in a gene (DNA)
• Translation
• mRNA code is read and translated into a string
  of amino acids that make up a protein

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RNA Ribonucleic Acid

• RNAs function is to take DNAs code, copy it and
  use it to make proteins
• Differs from DNA in that
• RNA is single stranded
• Contains Ribose as sugar
• Uracil instead of Thymine
• U-A

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3 types of RNA

• Messenger RNA (mRNA)
• Copies code from DNA template and brings it to
  the ribosome
• Transfer RNA (tRNA)
• Carries amino acids to ribosome to assemble into
  protein
• Ribosomal RNA (rRNA)
• Makes up ribosome and catalyzes protein synthesis

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Transcription

• RNA polymerase binds to a promoter and unzips
  DNA at a gene
• RNA polymerase adds complementary RNA nucleotides
  to DNA template making mRNA
• When gene ends, mRNA breaks away from DNA and DNA
  zips back up
• http//www.stolaf.edu/people/giannini/flashanimat/
  molgenetics/transcription.swf

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After transcription

• mRNA leaves the nucleus and heads to a ribosome
• mRNA letters will be read in groups of 3 called
  codons
• Each codon codes for 1 amino acid

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Translation

• mRNA binds to ribosome at start codon
• Always AUG (methionine)
• tRNA with complementary anticodon (UAC) brings
  over its amino acid
• Next codon is read, next amino acid is brought
  over by another tRNA

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• A covalent bond called a peptide bond forms
  between the 2 amino acids beginning a protein
  chain
• 1st tRNA is released, next codon is read, process
  repeats
• This continues until ribosome reaches a stop
  codon (UAA, UGA, or UAG)
• http//www.wisc-online.com/objects/index_tj.asp?ob
  jIDAP1302

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