BCHM 3050 1st Edition Lecture 26 Outline of Last Lecture I Transcriptional Regulation II Epigenetic Regulation III Regulation of Gene Expression Outline of Current Lecture I Blocking of Transcription or Translation by Antibiotics II Epigenetic Regulation Examples III Regulation of Gene Expression in Eukaryotes IV Locus Control Region LCR V RNA Processing Alternative RNA Splicing VI mRNA Degradation VII Operons VIII DNA Binding Proteins IX Glucose vs Lactose X PROG XI Activation of Lac Operon XII Role of Catabolite Activating Protein Current Lecture XIII Blocking of Transcription or Translation by Antibiotics These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute a Tetracycline blocks A site to prevent translation b Chloramphenicol inhibits peptidyl transferase c Erythromycin blocks translocation d Alpha Amanitin blocks transcription ONLY in eukaryotes binds to RNA Polymerase II e Cordycepin blocks messenger RNA works against translation fungus in caterpillar XIV Epigenetic Regulation Examples a This occurs on chromosome 19 b IGF2 and H19 are on the same chromosome inherit one from mom and one from dad c One can be turned off and passed onto offspring Mom s IGF2 is silenced and Dad s H19 is silenced across all humans d Example of epigenetics that is not affected by the environment e If you do not express H19 Angelman Syndrome no H19 mental disabilities and sterility issues f If IGF2 is silenced Prader Willi Syndrome no IGF2 g Women and med produce the same amount of proteins from the X chromosome because 1 of the woman s X chromosomes is silenced Barr bodies gender based epigenetics XV Regulation of Gene Expression in Eukaryotes a Promoters bind RNA polymerase and sometimes activators b Activation proteins Enhancers c Activators RNA polymerase proteins promotes d Modulators middle man that are sometimes needed but not always protein example of positive regulator e Connect RNA polymerase with activator f Enhancers promoters silencers are DNA g Activators RNA polymerase repressors are proteins that bind to DNA XVI Locus Control Region LCR a Beta Thalessemia is as common as cystic fibrosis b Beta subunit of hemoglobin is disfunctional c LCR is an example of an enhancer d If you have a mutation in the enhancer for the globin gene disease XVII RNA Processing Alternative RNA Splicing a Body makes one huge RNA strand with introns and exons and then the spliceosome enzyme complex regulates which mRNA to create based on the exons included in splicing alternate splicing b Example of Post transcriptional modifications along with capping and adding a poly A tail XVIII mRNA Degradation a Understand what the miRNA and siRNA do i siRNA small interfering RNA ii miRNA microRNA b Translational regulation i miRNA sticks to target mRNA and either degrades it or blocks translation machinery from attaching to it ii miRNA and siRNA are made in our body and stick to a certain mRNA or can promote loss of translation XIX Operons a Prokaryotes use operons which have one regulatory unit one promoter for multiple genes b One promoter that affects multiple genes at once XX DNA Binding Proteins a DNA binding proteins repressor activator histone etc b Most DNA binding proteins have these 4 motifs helix turn helix zinc fingers leucine zippers helix loop helix c If a protein has any of these motifs it can probably bind to DNA d DNA binding domain is rich in alpha helices e DNA binding proteins need weak interactions like hydrogen interactions but NEVER covalent bonds because the protein eventually needs to let go f Generally have glutamic acid residues which interact with basic residues g Positive regulation carried out be activators and allows for transcription h Negative regulation carried out be repressors and prevent transcription from occurring XXI i Repression turns off gene j Derepression turns on gene Glucose vs Lactose a Glucose is a six membered ring b When glucose and galactose come together lactose c Glycosidic bond between the two sugars that for lactose d Isomer of lactose is allo lactose e Lactose is broken down into glucose and galactose but some of it doesn t get broken down and turns into allo lactose f XXII The ability to break down lactose is an adapted trait so some people are still lactose intolerant PROG a Promoter Repressor protein different from the protein in eukaryotes Operator only in prokaryotes Genes b Repressor is constantly being made in bacteria c As long as operon is bound to repressor protein it is turned off and the gene cannot be made d The operon is constantly off in bacteria and it gets turned on in special occasions XXIII Activation of Lac Operon a When lactose is present in the medium and the bacteria does no have glucose then the allo lactose can bind to the repressor and remove it from the operator so that the operon can turn on b The enzymes are needed to break down and use lactose c Permease helps to get lactose into the cell d Galactosidase helps to break down lactose e Transacetylase helps to convert lactose to glucose to be used by the cell XXIV Role of Catabolite Activating Protein a When there is no glucose ATP converts to cAMP cAMP binds to CAP and serves as an activator and makes more genes increases the rate of transcription by about 50 times and promotes gene transcription b Glucose will convert cAMP back to ATP when prevent c Glucose reverses the balance of how much cAMP present in the environment
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