Lecture%2016

Lecture%2016 - BILD1 The Cell Posted today: Final Study...

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1 03/08/07 BILD1 - Lecture 16 1 BILD1 The Cell Prof. Lisa M. Boulanger 03/08/07 BILD1 - Lecture 16 2 Posted today: Final Study Guide, inner life of the cell (animation) Posted tomorrow: Problem Set 6 (LAST ONE!) Posted Saturday: Problem Set 5 KEY Practice Final exam Final Review Session : Saturday, March 17 th , 4:30-7:30pm 03/08/07 BILD1 - Lecture 16 3 DNA proofreading and repair DNA polymerase proofreading Excision repair Telomeres, telomerase Gene expression Transcription (DNA-directed synthesis of RNA) and translation (RNA-directed synthesis of protein) Steps separated by nucleus in eukaryotes Highlights from previous lecture: 1 μm 03/08/07 BILD1 - Lecture 16 4 Growing polypeptides Completed polypeptide Incoming ribosomal subunits End of mRNA (3 end) Polyribosome Ribosomes mRNA 0.1 μm Transcription Promoter, 3’ UTR, start, coding region, stop, 5’ UTR, terminator RNA polymerase opens DNA, moves 3’ Æ 5’ Base pairing with DNA antisense strand makes mRNA copy of sense strand, synthesized 5’ Æ 3’ Initiation, Elongation, Termination Eukaryotes: 5’ cap, 3’ poly-A tail, splicing Translation A, G, C, U become 20 amino acids through 3- base codons Reading frame In ribosome, tRNA links mRNA codon to amino acid via aminoaceyl-tRNA synthetase Polyribosomes Highlights from previous lecture: 03/08/07 BILD1 - Lecture 16 5 Direction of synthesis: DNA and RNA RNA polymerase Non-template strand of DNA RNA nucleotides 3 end CA UC C A A U T A GG T T C G U T A TCCA A 3 5 5 Newly made RNA Template strand of DNA Polymerase moves along DNA 3’ Æ 5’, synthesizes DNA or RNA 5’ Æ 3’ (nucleotides always added to 3’ end) DNA copying RNA transcription 03/08/07 BILD1 - Lecture 16 6 Sense and Antisense review Sense (coding , nontemplate) DNA strand is same sequence as RNA (except T instead of U) Antisense (noncoding , template) DNA strand is base-paired to make RNA RNA polymerase Sense strand of DNA RNA nucleotides 3 end U C C A U T A G G T T A A 3 5 5 Newly made RNA Antisense strand of DNA
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2 03/08/07 BILD1 - Lecture 16 7 Ribosome pulls RNA through 5’ Æ 3’, synthesizes polypeptides amino Æ carboxy (amino acids added to carboxy terminus) Direction of synthesis: protein Amino end Growing polypeptide Next amino acid to be added to polypeptide chain tRNA mRNA Codons 3 5 03/08/07 BILD1 - Lecture 16 8 Completing and Targeting the Functional Protein • Polypeptide chains – Undergo modifications after the translation process • After translation – Proteins may be modified in ways that affect their three-dimensional shape – Includes folding and post-translational modifications 03/08/07 BILD1 - Lecture 16 9 Targeting Polypeptides to Specific Locations • Two populations of ribosomes are evident in cells: – Free ribosomes in the cytosol • Mostly synthesize cytosolic proteins – Bound ribosomes • Synthesize proteins of endomembrane system and secreted proteins • Proteins destined for the endomembrane system or for
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This note was uploaded on 03/26/2010 for the course BENG 110 taught by Professor Schmid-schoenbein during the Spring '08 term at UCSD.

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Lecture%2016 - BILD1 The Cell Posted today: Final Study...

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