BCH 3170 Lecture Notes - Transcription Factor Ii F, Leucine, Eif2

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16 Oct 2011

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Dna binding proteins epigenetic control mrna processing (splicing, editing, transport, stability) eukaryotic mrna has exons and introns, introns need to be removed. Big difference in processes in eukaryotic cells versus prokaryotic the nucleus! Types of rna polymerase in eukaryotic systems: rna polymerase i. Synthesizes precursor of most rrnas: rna polymerase ii. Synthesized mrna precursors, snrnas: rna polymerase iii. Synthesizes precursors of 5s rrna, trnas and small nuclear and cytosolic rnas. Highlighted are the different domains of rna polymerase ii (there are about 12 domains) Synthesis occurs inside the hollow core of the enzyme. Clamp mobile arm that holds dna in place. Rudder separate strands of dna (protrudes inside the core) and reanneals the two strands together. Lid where newly transcribed rna molecule exits the enzyme. The rna polymerase has a long c-terminal domain (500 650 angstroms) Contains a conserved heptameric motif: [pro-thr-ser-pro-ser-tyr-ser] note that repeat is tyr-ser-pro- Extension of ctd coincides with onset of transcriptional elongation.

Related Questions

Choose Among (and **explain why** when appropriate): (1)Nucleus, (2) RNA Polymerase, (3) Cytoplasm, (4) DNA, (5) Enzyme ,(6) Plasma Membrane, (7) Lysosome

-the molecular source of information for transcription?
-the main enzyme for making a polymer of RNA?
-location of transcription in a eukaryotic cell?
-location of transcription in a prokaryotic cell?
-location of translation in a eukaryotic cell?
-location of translation in a prokaryotic cell?

1. There are viruses, called bacteriophage, that infectbacterial cells. Following viral entry, the cell begins tosynthesize viral DNA and viral proteins, leading to the productionof mature virus and the death of the bacterial cell. During thecourse of viral infection, transcription of bacterial genes isturned off so that transcription of viral genes predominates. Whichof the following is the most likely explanation for how the virusmanages to shift transcription from bacterial genes to its owngenes?

a. it synthesizes a viral RNA polymerase that recognizes onlyviral promoters

b. it synthesizes a viral DNA polymerase that recognizes onlyviral origins

c. it synthesizes a viral sigma subunit that directs thebacterial RNA polymerase to viral promoters

d. it has special viral ribosomes that only translate viralproteins

2. Unlike bacterial transcripts, eukaryotic RNA transcripts arechemically modified because:

a. Chemical groups help protect the mRNAs from degradation inthe eukaryotic cytoplasm, bacterial mRNAs are not degraded

b. Chemical groups facilitate the transport of eukaryotic RNAsfrom the nucleus to the cytoplasm, bacterial RNAs are synthesizedin the cytoplasm

c. Eukaryotic RNA polymerases cannot transcribe genes unlessthey are chemically modified, bacterial RNA polymerases transcribeunmodified genes

d. Transcripts in eukaryotic cells contain non coding regionsthat must be removed, bacterial transcripts contain only codingsequence

e. b and d

3. Termination of transcription in both E. coli and eukaryoticcells occurs because

a. there is a termination signal in the DNA following the genesequence.

b. there is a hairpin structure followed by a string of U

copperturtle968

1. How is the structure of eukaryotic DNA and chromosomes related to how transcription occurs?(Hint: histones and winding is important)

2.Compare RNA polymerase in bacteria to the RNA polymerase in eukaryotic cells? What are the structural differences? How does this relate to how each works?

3.Compare and contrast the promoters found in prokaryotes and eukaryotes.

4.How is initiation started in eukaryotes?

5.What are transcription factors and what role do they play?

6.How are elongation and termination similar in eukaryotes & prokaryotes? How do they differ?

BCH 3170 Lecture Notes - Transcription Factor Ii F, Leucine, Eif2

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