gene

School of Biotechnology Molecular Cell Biology Group 5: 1. Tran Thi Thuy Linh BT070049 2. Truong Thi Quynh Tram BT070083 3. Tran Thi Thu Hoai BT070116 4. Doan Thien Thanh BT070134 Submit to Dr Nguyen Thi Hue • Introduction • RNA Transcription • Overview of Transcription Control Gene Expression • Conclusion Main contents Detailed Contents • Introduction • RNA Transcription: • Overview • Transcription in Prokaryote • Transcription in Eukaryote • RNA Polymerase • Overview of Transcription Control Gene Expression 1. Transcription Factors 2. Overview of control Gene Expression 3. Control of Gene Expression in Prokaryote: 4. Control of Gene Expression in Eukaryote • Conclusion Introduction • In bacteria, gene control serves mainly to allow a single cell to adjust to changes in its environment. • In multicellular organisms, environmental changes also induce changes in gene expression. • Gene expression in both prokaryotes and eukaryotes is regulated primarily by mechanisms that control the initiation of transcription. RNA Transcription • Transcription is a process in which one DNA strand is used as template to synthesize a complementary RNA. • Since both DNA coding strand and RNA strand are complementary to the template strand, they have the same sequences except that T in the DNA coding strand is replaced by U in the RNA strand. Schematic illustration of transcription. (a) DNA before transcription. (b) During transcription, the DNA should unwind so that one of its strand can be used as template to synthesize a complementary RNA. Transcription in Prokaryotes • Binding of the polymerase's δ factor to promoter can catalyze unwinding of the DNA double helix. • The most important δ factor is Sigma 70, whose structure has been determined by x-ray crystallography. • The promoter is rich in A and T. The A-T pair involves two hydrogen bonds whereas the C-G pair involves three hydrogen bonds. • The DNA replication origin is also rich in A and T. b) The structure of Sigma 70 and its DNA binding site. (a) Structure of Sigma 70, residues 114 to 448. (b) A model for the binding between Sigma 70 and the promoter, based on biochemical studies. Residues Y425, Y430, W433 and W434 are directly involved in the unwinding (melting) of the double helix. a) [...]... promoter regions of DNA adjacent to the genes that they regulate Transcription factors use a variety of mechanism for the regulation of gene expression 2 Control of Gene Expression • Gene expression is the process by which inheritable information from a gene, such as the DNA sequence, is made into a functional gene product, such as protein or RNA • Steps of gene expression: -Transcription step -Translation... protein Regulation of Gene Expression • Regulation of gene expression (or gene regulation) is the cellular control of the amount and timing of appearance of the functional product of a gene • Regulated stages of gene expression consists of: -Chromatin domains -Transcription -Post-transcriptional modification -RNA transport -mRNA degradation -Post-translational modification 3 Control of Gene Expression in... Overview of Transcription Control Gene Expression 1 Transcription Factors Transcription factors are essential for the regulation of gene expression and consequently are found in all living organisms The preinitiation complex binds to promoter regions of DNA upstream to the gene that they regulate In eukaryotes, an important class of transcription factors called general transcription factors (GTFs)The... Prokaryotic genes to be regulated in the same manner are grouped together in operons, under the control of a single promoter and operator • The lactose operon (lac operon for short), which contains genes that encode enzymes responsible for lactose metabolism The lac operon looks like this: • The three structural (protein-encoding ) genes of the lac operon are lac Z, lac Y, and lac A 4 Control of gene expression... eukaryotes Conclusion The control of gene expression can occur at any step in the pathway from gene to functional proteins These levels of control include chromatin packing, transcription, RNA processing, translation, and various alterations to the protein product References • Molecular Cell Biology, 5th ed - ISBN 0716743663 – 967 • Daniel L Hartl, Elizabeth W Jones, Genetics Principles and Analysis,... three classes of RNA polymerases: I, II and III, focus on the RNA polymerase II (Pol II), which is involved in the transcription of all protein genes • RNA Pol II does not contain a subunit similar to the prokaryotic s factor • The RNA Pol II is associated with six general transcription factors: TFIIA, TFIIB, TFIID, TFIIE, TFIIF and TFIIH, (where "TF" stands for "transcription factor" and "II" for the RNA...Base sequences in promoter regions of several genes in E coli The consensus sequences located 10 and 35 nucleotides upstream from the transcription start site (+1) are indicated Promoters vary tremendously in their ability to promote transcription... Daniel L Hartl, Elizabeth W Jones, Genetics Principles and Analysis, 4th ed • http://biotech.about.com/od/proteinengineeri ng/f/transcriptfact.htm • http://www.ndsu.nodak.edu/instruct/mcclea n/plsc431/geneexpress/eukaryex1.htm  . Control Gene Expression 1. Transcription Factors 2. Overview of control Gene Expression 3. Control of Gene Expression in Prokaryote: 4. Control of Gene Expression. of Gene Expression • Gene expression is the process by which inheritable information from a gene, such as the DNA sequence, is made into a functional gene