RNA: Posttranscriptional Modifications By Amr S. Moustafa, M.D.; Ph.D.

Slides:

Advertisements

Similar presentations

Lecture 4: DNA transcription

Advertisements

Control of Gene Expression

RNA Synthesis (Transcription) By Amr S. Moustafa, M.D.; Ph.D.

Lecture 4: DNA transcription

Chapter 21 (Part 2) Transcriptional Regulation and RNA Processing.

A. Structure of RNA B. Major Classes of RNA C. Transcription in Prokaryotes D. Transcription in Eukaryotes E. Post-transcriptional Processing of Eukaryotic.

Section 8.6: Gene Expression and Regulation

Gene Expression. 2 Gene expression? Gene expression?  Biological processes, such as transcription, and in case of proteins, also translation, that yield.

Lecture 6 of Introduction to Molecular Biology 生理所蔡少正

(CHAPTER 12- Brooker Text)

Step 1 of Protein Synthesis

CHAPTER 3 GENE EXPRESSION IN EUKARYOTES (cont.) MISS NUR SHALENA SOFIAN.

Posttranscriptional Modification of RNA

Relationship between Genotype and Phenotype

RNA (Ribonucleic acid)

Transcription: Synthesizing RNA from DNA

Day 2! Chapter 15 Eukaryotic Gene Regulation Almost all the cells in an organism are genetically identical. Differences between cell types result from.

Transcription transcription Gene sequence (DNA) recopied or transcribed to RNA sequence Gene sequence (DNA) recopied or transcribed to RNA sequence.

Gene Structure and Function

Regulation of Gene Expression

Gene Control Chapter 11. Prokaryotic Gene Regulation Operons, specific sets of clustered genes, are the controlling unit Promoter: sequence where RNA.

Gene structure in prokaryotes * In prokaryotic cells such as bacteria, genes are usually found grouped together in operons. * The operon is a cluster of.

Control of Gene Expression. Steps of gene expression Transcription – DNA is read to make a mRNA in the nucleus of our cells Transcription – DNA is read.

RNA Processing By: Kelvin Liu, Jeff Wu, Alex Eishingdrelo.

Transcription Packet #20 5/31/2016 2:49 AM1. Introduction  The process by which information encoded in DNA specifies the sequences of amino acids in.

Control Mechanisms. Four Levels of Control of Gene Expression Type of ControlDescription Transcriptional Regulates which genes are transcribed. Controls.

Section 2 CHAPTER 10. PROTEIN SYNTHESIS IN PROKARYOTES Both prokaryotic and eukaryotic cells are able to regulate which genes are expressed and which.

REVIEW SESSION 5:30 PM Wednesday, September 15 5:30 PM SHANTZ 242 E.

Gene Regulation in Prokaryotes - plasmid, not protected by nuclear envelope - DNA is not bound up with histones -One of the best known pathways is the.

(distal control elements)

RNA & Transcription. RNA (Ribonucleic Acid) Journal For all your RNA news!

Prokaryotic cells turn genes on and off by controlling transcription.

Transcription in Prokaryotic (Bacteria) The conversion of DNA into an RNA transcript requires an enzyme known as RNA polymerase RNA polymerase – Catalyzes.

Complexities of Gene Expression Cells have regulated, complex systems –Not all genes are expressed in every cell –Many genes are not expressed all of.

Control of Gene Expression Chapter DNA RNA Protein replication (mutation!) transcription translation (nucleotides) (amino acids) (nucleotides) Nucleic.

Page Example problems: Page 324, #2,3,9. Transcription The process of making… RNA review Very similar to DNA except: Has a ribose sugar instead.

Eukaryotic Gene Structure. 2 Terminology Genome – entire genetic material of an individual Transcriptome – set of transcribed sequences Proteome – set.

TRANSCRIPTION Copying of the DNA code for a protein into RNA Copying of the DNA code for a protein into RNA 4 Steps: 4 Steps: Initiation Initiation Elongation.

Transcription. Recall: What is the Central Dogma of molecular genetics?

Controlling Gene Expression. Control Mechanisms Determine when to make more proteins and when to stop making more Cell has mechanisms to control transcription.

Central Dogma Molecular Influences on Genetic Regulation.

Chapter 13: Gene Regulation. The Big Picture… A cell contains more genes than it expresses at any given time – why? Why are cells in multicellular organisms.

Transcription of the Genetic Code: The Biosynthesis of RNA Mar 1, 2015 CHEM 281.

Gene Expression & Regulation Chapter 8.6. KEY CONCEPT Gene expression is carefully regulated in both prokaryotic and eukaryotic cells.

Gene Regulation.

Posttranscriptional Modification of DNA Primary Transcript – newly synthesized RNA Mature tRNA molecules are generated in both prokaryotes and eukaryotes.

TRANSCRIPTION (DNA → mRNA). Fig. 17-7a-2 Promoter Transcription unit DNA Start point RNA polymerase Initiation RNA transcript 5 5 Unwound.

Figure 16.5 The double helix. Figure 16.3 The structure of a DNA stand.

1 RNA ( Ribonucleic acid ) Structure: Similar to that of DNA except: 1- it is single stranded polyunucleotide chain. 2- Sugar is ribose 3- Uracil is instead.

Factors Involved In RNA synthesis and processing Presented by Md. Anower Hossen ID: MS in Biotechnology.

RNA Structure, synthesis, and processing

Eukaryotic Gene Structure

Lecture 15 From Gene to Protein.

Figure 18.3 trp operon Promoter Promoter Genes of operon DNA trpR trpE

Posttranscriptional Modifications of RNA

Prokaryotic cells turn genes on and off by controlling transcription.

Prokaryotic cells turn genes on and off by controlling transcription.

Controlling Gene Expression

The Operon Hypothesis The Operon Hypothesis was developed by 2 researchers: Jacob and Monod It explains how genes are regulated in prokaryotes. They received.

Regulation of Gene Expression

Gene Regulation.

Prokaryotic cells turn genes on and off by controlling transcription.

Prokaryotic cells turn genes on and off by controlling transcription.

From gene to protein.

Chapter 6.2 McGraw-Hill Ryerson Biology 12 (2011)

Prokaryotic cells turn genes on and off by controlling transcription.

Prokaryotic cells turn genes on and off by controlling transcription.

Prokaryotic cells turn genes on and off by controlling transcription.

Relationship between Genotype and Phenotype

Presentation transcript:

RNA: Posttranscriptional Modifications By Amr S. Moustafa, M.D.; Ph.D.

Enhancers and Silencers Cis-acting DNA sequences Enhancers: stimulate; Silencers: inhibit Upstream or downstream Close or thousands bp from promoter DNA response elements: activators-binding sites On either strand of DNA Bending of enhancer DNA allows activators (specific TF) to interact with: General TF and RNA polymerase II

Enhancers and Silencers Cis-acting DNA sequences Enhancers: stimulate; Silencers: inhibit Upstream or downstream Close or thousands bp from promoter DNA response elements: activators-binding sites On either strand of DNA Bending of enhancer DNA allows activators (specific TF) to interact with: General TF and RNA polymerase II

Transcription Factors General: Binds to promoter Activators: Binds to Enhancer

The Lac Operon Operon: Coordinately expressed genes Structural and their regulatory genes Lac operon: (For E. coli catabolism of lactose) Structural genes: code for 3 enzymes: Lac Z gene: β-galactosidase Lac Y: permease Lac A: thiogalactoside transacetylase Regulatory Sequences: Promoter (P) region Operator (O) site CAP-binding site LacI gene: repressor protein

The Lac Operon Operon: Coordinately expressed genes Structural and their regulatory genes Lac operon: (For E. coli catabolism of lactose) Structural genes: code for 3 enzymes: Lac Z gene: β-galactosidase Lac Y: permease Lac A: thiogalactoside transacetylase Regulatory Sequences: Promoter (P) region Operator (O) site CAP-binding site LacI gene: repressor protein

The Lac Operon: Off

The Lac Operon: On

The Lac Operon: Off

Posttranscriptional Modifications The rRNA and tRNA: Both pro- and eu-karyotes The mRNA: Only eukaryotes

Posttranscriptional Modifications: The rRNA Ribonucleases Site: Nucleolus Protein association: Before and during modifications e 5 S rRNA: Separate modification

Posttranscriptional Modifications: The tRNA Ribonucleolytic cleavage: 16-Nucleotides at 5’-end 2 Uracil at 3’-end 14 Nucleotides (intron) at anticodon loop 2. Addition of CCA at 3’-end Nucleotidyltransferase 3. Base modifications

Posttranscriptional Modifications: The tRNA - 2

Posttranscriptional Modifications: The euokaryotic mRNA ’- Capping: 7-Methyl-guanosine 2. 3’- Poly-A tail 3. Removal of introns and splicing of exons

Posttranscriptional Modifications: The euokaryotic mRNA - 2 Cap: 7-Methylguanosine triphosphate Bond: Unusual 5’-5’ triphosphate Site: Nucleus & cytoplasm Enzymes: Nuclear guanylyltransferase Cytoplasmic methyl transferase Methyl donor: SAM Functions: Initiation of translation Stabilizes mRNA

Posttranscriptional Modifications: The euokaryotic mRNA - 3 3’- Poly-A tail: 40 – 200 Exception: mRNA for histones and interferons Enzyme: Nuclear polyadenylate polymerase Site: Nucleus & cytoplasm Signal: AAUAAA Functions: Stabilizes mRNA Facilitates its exit from nucleus Poly-A tail: Shortened after mRNA enters cytosol

Posttranscriptional Modifications: The euokaryotic mRNA - 4

Posttranscriptional Modifications: The euokaryotic mRNA - 5 Removal of introns and splicing of exons: Exons:Coding sequences for proteins Spliceosome: Binding of snRNPs & primary transcript Correct alignment of neighboring exons allows splicing of exons The snRNPs: snRNAs + proteins Introns:Sequences not coding for proteins No, few or many introns/mRNA

Posttranscriptional Modifications: The euokaryotic mRNA - 5 Systemic lupus Erythematosus: Auto Abs against snRNPs β-Thalassemia: Splice site mutations

Posttranscriptional Modifications: The euokaryotic mRNA - 6 Alternative splicing: A diverse set of proteins from a small set of genes Selective tissue expression e.g., tissue-specific tropomycin