Protein Synthesis

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Protein Synthesis

• Chapter 10.3

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• Protein synthesis- the production of proteins
• The amount and kind of proteins produced in a
  cell determine the structure and function of the
  cell

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The Genetic Code

• Genetic code- the correlation between the
  nucleotide sequence and an amino-acid sequence
• During protein synthesis, the sequence of
  nucleotides is translated into a sequence of
  amino acids

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• Codon- each combination of 3 mRNA nucleotides
• Start codon (AUG)- engages a ribosome to start
  translating an mRNA molecule
• Stop codons (UAA, UAG, UGA)- cause the ribosome
  to stop translating

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Translation

• Translation- the process of assembling
  polypeptides from information encoded in mRNA
• Begins when mRNA leaves the nucleus through pores
  in the nuclear membrane
• mRNA migrates to a ribosome in the cytosol

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tRNA and Anticodons

• Anticodon- a region of tRNA consisting of three
  bases complementary to the codon of mRNA
• Amino acids floating freely in the cytosol are
  transported to the ribosomes by tRNA molecules

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• Ribosomes have three binding sites that are
  important to translation
• One site holds a mRNA transcript so its codons
  are accessible to rRNA molecules
• The other two sites hold tRNA whose anticodons
  pair with the mRNA codons

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Protein Assembly

• Assembly begins when a ribosome attaches to the
  start codon (AUG) on an mRNA transcript
• As a ribosome moves along an mRNA transcript,
  each mRNA codon is paired with its tRNA anticodon

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• Practice sequences!!
• Study for the Ch 10 test!!
• Know the Ch 10 vocabulary!!