The%20Ribosome

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• The Ribosome
• Is part of the cellular machinery for
  translation, polypeptide synthesis

Figure 17.1
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Evidence from the Study of Metabolic Defects

• In 1909, British physician Archibald Garrod
• Was the first to suggest that genes dictate
  phenotypes through enzymes that catalyze specific
  chemical reactions in the cell

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Nutritional Mutants in Neurospora Scientific
Inquiry

• Beadle and Tatum causes bread mold to mutate with
  X-rays
• Creating mutants that could not survive on
  minimal medium each mutant was defective in a
  single gene supporting the one gene-one enzyme
  hypothesis

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Overview the roles of transcription and
translation in the flow of genetic information
No mRNA processing
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Question

• How does RNA (ribonucleic acid) differ from DNA
  (deoxyribonucleic acid)?

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The triplet code
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The dictionary of the genetic code
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The stages of transcription initiation,
elongation, and termination
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The initiation of transcription at a eukaryotic
promoter
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RNA processing addition of the 5? cap and
poly(A) tail
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RNA processing addition of the 5? cap and
poly(A) tail
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• The function of the cap is
• prevent mRNA degradation by hydrolytic enzymes
• helps attach to the ribosome
• Function of the 3 tail
• same functions as the 5cap
• also helps facilitate export of mRNA from nucleus

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RNA processing RNA splicing
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The roles of snRNPs and spliceosomes in mRNA
splicing
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RNA Splicing

• Removes noncoding regions called introns
• snRNPs (small nuclear ribonucleoproteins)
  recognize the splicing signals that are at the
  ends of introns
• The RNA in the snRNP is called snRNA (small
  nuclear RNA)
• spliceosomes are the larger protein assemblies
  formed by the joining of snRNPs

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Correspondence between exons and protein domains
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The structure of transfer RNA (tRNA)
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The structure of transfer RNA (tRNA)
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Translation the basic concept
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An aminoacyl-tRNA synthetase joins a specific
amino acid to a tRNA
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The anatomy of a functioning ribosome
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The initiation of translation
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The elongation cycle of translation
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The termination of translation
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Peptide Bonds Join Amino Acids
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Polyribosomes
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Coupled transcription and translation in bacteria
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The signal mechanism for targeting proteins to
the ER
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The polypeptides of proteins destined for the
endomembrane system are marked by a signal
peptide, which targets the protein to the ER.
A signal recognition particle (SRP) functions
as an adaptor that brings the ribosome to a
receptor protein built into the ER membrane.
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The molecular basis of sickle-cell disease a
point mutation
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Categories and consequences of point mutations
Base-pair substitution
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Categories and consequences of point mutations
Base-pair insertion or deletion
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A summary of transcription and translation in a
eukaryotic cell