Week 0 Thursday Lecture MCDB 101A
Week 0 Thursday Lecture MCDB 101A MCDB 101A
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This 2 page Class Notes was uploaded by Courtney Conway on Monday September 26, 2016. The Class Notes belongs to MCDB 101A at University of California Santa Barbara taught by Thrower in Fall 2016. Since its upload, it has received 56 views.
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Date Created: 09/26/16
Week 0 Lecture 1 22 September 2016 Thrower Molecular Genetics of Prokaryotes Come to lecture, go to section, do every problem in reader (1/3) questions of exam from reader (AS students ucen) CLAS, study group Exam Schedule check Last year MT Register clicker What is Genetics? - “study of genes” - “manipulation of DNA to study cellular organismal functions” - study of biological properties transmitted from parent to offspring (most accurate and modern) Prokaryotes vs Eukaryotes - Proks. have no nucleus, no histones, no membrane bound organelles- euks. do - smaller ribosomes(slightly) 70S, while euks. are 80S - pores allow entrance of larger molecules vs endocytosis in euks. - respiration from membrane vs mitochondria in euks. - chromosomes are single and circular vs multiple and linear in euks. - no sterols in membrane - There are always exceptions! Exceptions Streptomyces (Prokaryote Group) - large # antibiotics produced by these, have multiple linear chromosomes in contrast to normal proks. Mycoplasma- type of cholesterol - parasites that can temporarily leave their host to steal membrane for protection Gemmata Obscuriglobus: - typical sized prok. organism, but there’s a ring inside membrane that encloses the DNA- has a nucleus & nuclear envelop - several sister organisms with partial enclosed rings - ribosomes inside nucleus and inside and out, similar to rough ER in euks. - has cytoplasm like substance called karyoplasm - highly compartmentalized bacteria - no way for RNA to get out, most translations take place inside nucleus - does functions similar to endocytosis Bacteriophage: - virus like body - head made of protein to protect DNA - core structure that’s hollow tube with rings that contract to insert DNA into host - tail fibers enabling phage to specifically attach to bacteria Terms to Know - Gene/cistron: basic unit of hereditary material - Genome: all chromosomal genes in org, distinguishes organism but not chromosomes - Locus: physical location of gene within genome (ex: plasmid)- loci is exact location for pair of chromosomes - Allele: alternate form of a gene (ex: bacteriophage) - Genotype: allelic composition of an org - Phenotype: outcome of given genotype - Haploid: one complete set of genes - Diploid: 2 comp sets of genes - Merozygote: a partial diploid, 2 or more copies of some genes Wild Type: allelic form most prominent in “wild” population (ex: natural location is water for gemmate) Mutation: genetic alteration, usually changes phenotype, usually not beneficial Mutant: have one or more mutatioms Reverse Mutation “Reversion”: second mutation that restores mutant to wild type Nomenclature: - grouped by genus and species- always italicize the gene name or the molecule that carries genetic info - Gene: lacZ- want the l to+be lower case for gene name Wild type: -lacZ Mutant: -lacZ - r s Drug resistance: -amp , amp - absence of ampicillin resistant gene, nothing is resistant to amp. - Protein: LacZ- never italicize protein name, usually capitalized Characterizing Genes - classical vs molecular Classical: having to do with phenotype only (ex: Mendellian genetics with flower and pea phenotype) Molecular genetics: - gene is like “open reading frame” of nucleotides that can be used for encoding protein DNA - compare functions of DNA sequence to match unknown genes with chemical outcome Bacterial Culture: - spread method: use agar to see individual colonies starting with indv cell- helps you characterize - suspension method: bact cells suspended in fluid Selective Method: point is to isolate to see different colonies - ex: red under acidic conditions, yellow under basic Auxotrophic Mutations: - grow bacteria in different types of media - Minimal Media: min carbon source, min energy source, nitrogen through NH , and trace 4 minerals - If there is an auxotrophic mutation, typically only grow on rich media Prototrophs grow on minimal - Rich media: bacteria will convert to media amino acid to make protein from rich media only, don’t know where mutation lies initially, so supply everything it needs to see what prevents it from growing after- work backwards What grew on rich and not minimal “A gene is an element that encodes the information required to make an enzyme” –Beadle and Tatum - genes encode for enzymes Neurospora: not pathogenic - ex: typical brown food mold Auxotrophs: Bactria with auxotrophic mutation that targets specific metabolic enzymes that don’t allow growth on minimal media Prototrophs: bacteria that is able to grow on minimal media: considered to be “wild type” ID auxotrophic mutations in neurospora 1. tip dilution to the side 2. apply x-radiation to fungus as it’s growing: trying to mutate genes at faster rate - cant overdose radiation- want minimal dose to see mutations in organism 3. wait for spontaneous mutations to ID auxotrophic mutations - if no growth: discard, if continuing no growth repeatedly=auxotrophic mutation!! - if growth: redo to double check- no auxotrophic mutation - minimal media may be lacking source for basic growth (potential error) - growth only occurred when added certain source – helps ID bacterial organism 4. add specific amino acid until receive growth- each plate has different specific amino acid + the minimal media
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