BIOB11H3 Lecture Notes - Lecture 4: Molecular Biology, Ribosomal Rna, Uracil

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turquoisejackal716

14 Oct 2011

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Sps: figs 11-4, 6, 7, 9, 12, 13, 14. Beadle and tatum experiment (1940s: laid foundation of biochemical genetics, support for one gene/one enzyme" hypothesis, b&t awarded nobel prize in 1958. In this case: mutation in gene encoding protein involved in making the vitamin pantothenic acid. If enz2 gene mutated, then providing cells with c will. Rescue", but providing a and b will not. Beadle & tatum proposed: one gene-one enzyme hypothesis. 5" to 3" (strand being synthesized: unwinding dna creates topological stress. Supercoiling alleviates torsional stress:also see fig 13-6: ntp hydrolysis provides energy, many polymerases can act simultaneously. Consensus sequences located at -35 and -10 in prokaryotic genes. Pol i sensitivity to !-amanitin rnas large (rrnas) insensitive. Pol iii moderately sensitive small rnas (5s, trnas) Nucleolus: clusters" of rrna genes and the site of ribosome assembly. Rna size can be estimated based on sedimentation of the molecule during centrifugation.

Related Questions

9. The nucleotide on the DNA template that marks the starting point for RNA synthesis is called

a. 0 (zero point)

b. +1

c. -1

d. Start codon

e. TATA

10. Which bacterial RNA polymerase synthesizes tRNA?

a. RNA polymerase I

b. RNA polymerase II

c. RNA polymerase III

d. Core enzyme

e. Promoter

11. What general transcription factor has enzymatic activity?

a. Operator

b. TFIIH

c. eIF2

d. RNAP II

e. CTD

12. What enzyme activity/activities is/are known to be associated with the transcription factor in the previous question?

a. protein kinase and a DNA helicase

b. protein phosphatase

c. ribozyme

d. synthesis of RNA

e. a and c

fuchsiaclam492

Prokaryotes don't have a nucleolus but still produce a lot ofribosomal RNAs. Transcription of prokaryotic rRNA mostly likelyinvolved which of the following transcription factors? WHY?

a) Sigma 28

b) Sigma 38

c) Sigma 70

d) TBP (TATA Binding Protein)

Pantothenic acid (vitamin B5 ) is the substrate for the biosynthesis of coenzyme A, an essential cofactor in energy metabolism. Because mammals obtain vitamin B5 from their diet, the biosynthesis of pantothenic acid in pathogenic bacteria has been identified as a drug target. Ketopantoate reductase (KPR) catalyzes the NADPH-dependent reduction of ketopantoate (KP) to pantoate, the essential precursor of pantothenic acid. Previous structural and kinetic studies have focused on Escherichia coli KPR, a monomeric enzyme with globular N- and C-terminal domains. The N terminal domain of E. coli KPR contains a Rossmann fold for binding NADPH. KP binds in the active site that is formed in the interface between the domains. The catalytic reaction follows a sequential ordered bi-bi kinetic mechanism in which the enzyme binds NADPH first, followed by KP for the hydride transfer. Here we report the structural and kinetic analysis of KPR from Staphylococcus aureus, an important human pathogen. Unlike the E. coli enzyme, S. aureus KPR forms a stable, dimeric complex that is highly conserved among several deeply divergent KPRs. Steady state analysis of the S. aureus enzyme also displays positive cooperativity with respect to the cofactor. We present evidence that the cooperativity is best explained by a random addition mechanism with a kinetically preferred path. Thus, the mechanism of S. aureus KPR is distinct from those of previously described members of the family of 2-hydroxyacid dehydrogenases.

(I always have trouble reading and comprehending scientific articles) What's the motivation for the investigation? How is the author's motivation for performing the investigation related to other work in the field?

BIOB11H3 Lecture Notes - Lecture 4: Molecular Biology, Ribosomal Rna, Uracil

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