Announcements. Homework - problem set 5 - due this Friday Reading Ch. 14: Skim btm 391 -top 397. Skip rest of 397- 403. Review of Last Lecture. I. tRNA and the genetic code II. Transcription - prokaryotes III. Transcription - eukaryotes. Outline of Lecture 25.
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Homework - problem set 5 - due this Friday
Reading Ch. 14: Skim btm 391 -top 397.
Skip rest of 397- 403.
I. tRNA and the genetic code
II. Transcription - prokaryotes
III. Transcription - eukaryotes
I. RNA processing in eukaryotes
II. Translation of mRNA into protein - tRNA and ribosomes
III. Three steps of translation
IV. First evidence that proteins are important to heredity
V. One gene- one enzyme hypothesis
Aminoacyl tRNA synthetase
S = Svedberg, a measure of sedimentation in centrifuge
III. Translation has 3 Steps, Each Requiring Different Supporting Proteins
Overview of Prokaryotic Translation Supporting Proteins
Initiation Supporting Proteins:1. Binding of initiation factors to small subunit.2. Binding of first tRNA and mRNA to small subunit.3. Binding of large subunit.
Elongation: Supporting Proteins1. Binding of next tRNA using EFs at A site.2. Peptide Bond formation between 2 amino acids.3. Translocation of ribosome.
E P A
E P A
E P A
E P A
E P A
Termination: Supporting Proteins1. Binding of Release Factor to Stop Codon UGA, UAA, UAG.2. Disassembly
EM of Polyribosomes: >1 Ribosome working on the same mRNA Supporting Proteins
Rabbit Hemoglobin mRNA
Midgefly Salivary Gland
with Nascent Polypeptide
Note: occurs in cytoplasm.
IV. Inborn Errors of Metabolism Provided First Evidence that Genes Encode Proteins
Alkaptonuria is an inherited disorder
first described by Garrod (1902) and Willliam Bateson.
Phenylketonuria (PKU) Genes Encode Proteins
Metabolic Pathways for Phe and Tyr Genes Encode Proteins
Other Metabolic Disorders in the Pathway Genes Encode Proteins
V. Beadle and Tatum: One Gene - One Enzyme (Polypeptide) Genes Encode Proteins