Lecture 13: Transcription

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Lecture 13 Transcription Translation (continue)
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Outline

• Genetic code
• Transcription
• Translation
• Prokaryotes vs. eukaryotes

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Translation

• Use sequence information of mRNA to generate
  proteins
• Required components
• mRNAs
• Ribosome ( proteins rRNAs)
• tRNAs

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Translation in slow motion
I. Initiation phase
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Translation in slow motion
II. Elongation phase
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Translation in slow motion
III. Termination phase
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tRNAs

• small RNAs function as adaptors
• one end carries amino acid
• the other end recognize codon (anticodon)
• each amino acid has its own tRNA adaptor
• which machinery connect aa with tRNA?

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tRNAs

• small RNAs function as adaptors
• one end carries amino acid
• the other end recognize codon (anticodon)
• each amino acid has its own tRNA adaptor
• which machinery connect aa with tRNA?
• amino acyl tRNA synthetase
• How many of them are in cells?

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Base-pairing btw tRNA and mRNA

• do not follow the strict rules of
• watson/crick base-pairing
• (AU or GC)
• tRNAs contain unusual base at
• anticodon
• In theory, 64 tRNAs are required
• for 64 combinations of codons
• but, there are only 40 different
• tRNAs in human

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Overall view of genes to proteins
DNA sequence coding information other
information (promoter, terminator) for
polymerase mRNA sequence coding information
other (start and ending information) for
ribosome
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Prok. vs Euk. difference
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Exercise questions
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Exercise questions
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Announcement
No Homework for the nextweek, but Michelle will
have discussion classes.