Popular in Course
verified elite notetaker
Popular in Molecular, Cellular And Developmental Biology
Molecular, Cellular And Developmental Biology
verified elite notetaker
verified elite notetaker
This 8 page Class Notes was uploaded by Lauren Nagra on Wednesday September 3, 2014. The Class Notes belongs to a course at University of California Santa Barbara taught by a professor in Fall. Since its upload, it has received 50 views.
Reviews for MCDB 1A
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 09/03/14
Monday 1222013 03092014 1108 AM Gene Regulation in Prokaryotes Necessary to avoid transcripton and translation of genes that are not needed all the time more efficient use of metabolic resources Regulation of transcription is primary control point Operonpromotor operator and several structural genes Repressor protein that can bind to operator and prevent transcription of structural genes DNA sequences Operons inducible lac operon or repressible trp operon systems An Inducer Stimulates the synthesis of an Enzyme Cells have metabolic regulation Adding and removing inducer seeing induced level and basal level of Beta Gata and mRNA Positive and Negative Regulation Negative reguation protein is binding to DNA sequence blocking transcription repressor protein 0 Repressor in lac operon imposes NEGATIVE regulation in absence of this transcription can proceed Positive Reguation in absence of protein very little transcription Need activator protein 0 Activator is POSITIVE regulation in creases transcription The lac Operon of E coli and Its Regulator Diagram in sides figure 164 Two states of lac Operon Lactose absent If lactose is absent you get bound to something else transcription shuts down Lactose present Cannot bind to operator the transcription can happen 0 Enzymes are made to stob inducer when inducers are done transcription stops ANIMATION Inducer molecule results in expression of structural genes of the lac operon can go from RNA to protein Lac repressor is always present Lactose absent result lac binds to operator RNA can not get through Lactose present allolactose binds to repressor causing it to change its shape it can no longer bind to operate 0 Now RNA polymerase can transcribe 0 Proteins made participate in metabolism of lactose Catabolite Repression When glucose is abundant cAMP levels drop 0 Glucose HIGH cAMP LOW The CRP cAMP complex does not form Without the CRP cAMP complex RNA polymerase cannot bind to the promoter efficiently The lac structural genes are transcribed at a very low level almost off This is called CATABOLITE REPRESSION When preferred carbon source is available glucose other operons related to carbon utilization do not transcribe at high rate The lac operon is highly expressed only when 0 Gucose actose POSITIVE REGULATION High glucose lactose presentoff Low glucose lactose presenton Everything in bio has a gas pedal and brakes TABLE 161 Positive and Negative Regulation in the lac Operon The trp Operon A repressible System Some metabolites are required all the time Example amino acids are needed to charge tRNAs are needed at all times IF any amino acid tRNA is missing protein synthesis stops when ribosome is unable to insert correct amino acid Cell expresses genes needed to synthesize amino acid if it is not available forom the environment If amino acid level is adequate then it is more efficient to not express genes Repressible operon solves this problem Co repressor binds to operator in the presence of metabolite to prevent operon expression when amino acid level is inadequate You only need the enzymes if you haven39t gotten the stuff tryptophan from the environment It is one of those ones that you have to keep at a certain level always No tryptophan repressor cannot bind transcription can begin 0 Makes mRNA script translation enzymes of the tryptophan are produced Tryptophan present trp operon repressed The Eukaryote Genome Expression Eukaryotic genomes are larger than those of prokaryotes Much of eukaryotic DNA is noncoding Eukaryotes have multiple chromosomes In eukaryotes transcription and translation are physically separated Eukaryotes have more complex regulation than prokaryotes Eukaryotic genomes have more regulatory sequences and more regulatory proteins that bnid them Eukaryotic mRNA is transcribed in the nucleus exported to the cytoplasm where translation occurs Tuesday 1232013 03092014 1108 AM Transcription Repressors and Activators 3 RNA polymerases the one that does structural stuff is RNA polymerase two transcribes proteins promoterstart site label with 1 each mRNA makes ONE polypeptide binding site and rna polymerase brings the thing to where it needs to be to be translated enhancer short DNA sequence Motif o wo enhancer 1enhancer 100 0 can alter transcription up to 100 fold Very important in determining level of expression of gene 0 there are many enhancers Coordinating Gene Expression Heterochromatin prevents gene expression Heterochromatin is found in the inactive X chromosome of mammals One of the X chromosomes in each cell of a female is inactivated early in development The chromosome remains condensed and appears as a Barr body under the microscope Condensation physically prevents DNA fromm being transcribed Methylation of cytosine on DNA may be involved with the inac va on Euchromatin generay active Initially in zygote two X chromosomes are not condensed inito heterochromatin Early on there is a switch that selects one X chromosome to be hetereo Barr body highly condensed X chromosome Chemicals that change Euchromo heterochromosome BARR BODY Xist gene controls whether or not X chromosome becomes a Barr body 0 Produces RNA that is non coding o Chromosome expressing Xist decide which chromosome is gonna be Barr body 0 Xist turns off all the other genes X from mom and X from dad in girls it39s not always the same one that is the Barr body 0 Each cell decides individually to use maternal or paternal o The cells stemming from that cell daughter cells will have same decision Female Carriers for X inked traits Female carriers are heterozygous for X inked traits Inactivation in each cell due to Barr body formation of one allele or the other occurs in early development Selection of X chromosome for inactivation is random 0 Imprinting on X chromosomes by methylation of DNA which persist throughout mitosis Mosaic expression patter in adult shows clonal propagation of Barr body Imprint is removed during meiosis PERSISTS THROUGH MITOSIS REMOVED THROUGH MEIOSIS Red green color blindness example 0 Woman that has 1 X chromo for this half of her cones can see color other half can not half is enough to see color though CALICO CAT what makes the orange and black patches 0 Different X chromosomes expressing pigment genes at certain places 0 Some cells will make orange hair close to each other 0 Other cells will make black hair Barr body is suppressed In black hair orange is suppressed in Barr body 0 Male calico can occur because of disjunction XXY ICLICKER In inducible operon systems 0 The inducer allows transcription DNA Methylation An epigenetic change Methylation typically occurs in promoters Methylation suppresses expression We can regulate expression of genes by regulating CH3 in promoter Epigenetics You can change your methylation pattern by doing stuff in your youth and this pattern can be passed down to your children Genomic imprinting In mammals eggs and sperm develop different methylation patterns For abou 200 genes offspring inherit an inactive methylated copy and an active demethylated one You need sex specific methylation patterns maternal and paternal pattern is needed to have a normal zygote Wednesday 1242013 Small regulatory RNAs MicroRNAs 1st miRNA described in Ceegans in 1993 2006 Nobel Prize to Andrew Fire and Craig Mello later found to be widely distributed in all plants and animals short noncoding RNAs involved in post transcriptiona regulation of gene expression 30 o of all protein coding genes in mammals are regulated by miRNAs short 2022 nucloetides RNA molecules play a role in many human diseases including cancer cardiovascular dsease diabetes mental disorders and viral infection mRNA Inhibition by RNAs miRNA dicer processes them and forms a RISC complex single strand RNA 2022 NT 0 base pairing with target mRNA 9 inhibition of translation 0 getting rid of RNA siRNAs9degradation miRNA biogenesis primary mRNA gets spliced gets exported dicer starts chewing away then you add up with something that can split up into Biological rationales of mRNA mediated regulation CHAPTER 18 Recombinant DNA and Biotechnology What is recombinant DNA How are new genes inserted into cells What sources of DNA are used in cloning What other tools are used to study DNA function What is biotechnology How is biotechnology changing medicine agriculture and the environment Cloning DNA Source of insert DNA genomic DNA cDNA PCR product DNA Vector plasmid circular self replicating DNA virus artificial chromosome Host E coli yeast cultured eukaryotic cells Ligate insert and vector to make recombinant DNA molecule in test tube Transform recombinant DNA molecule into host signals replication which will replicate and make many copies of each clone
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'