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Chapter 20 DNA Transformation A. P. Biology Mr. Knowles Liberty Senior High School
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pGLO™ Transformation and Purification of Green Fluorescent Protein (GFP)
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Central Framework of Molecular Biology DNA RNA ProteinTrait
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The Central Dogma Trait (phenotype)
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Using GFP as a biological tracer http://www.conncoll.edu/ccacad/zimmer/GFP-ww/prasher.html With permission from Marc Zimmer
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Links to Real-world GFP is a visual marker Study of biological processes (example: synthesis of proteins) Localization and regulation of gene expression Cell movement Cell fate during development Formation of different organs Screenable marker to identify transgenic organisms Real-World Applications
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GFP Transformed into Bacteria
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Applications of GFP
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GFP in a Plant, Arabadopsis
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GFP in a Mouse
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Genetically Engineered Fish
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Bacterial DNA Plasmid DNA Bacterial cell Genomic DNA
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What is a plasmid? An extrachromosomal, circular piece of autonomously replicating DNA. Originally evolved by bacteria. May express an antibiotic resistance gene or be modified to express proteins of interest.
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The Many Faces of Plasmids Scanning electron micrograph of supercoiled plasmid Graphic representation Plasmids act as vectors – carriers for foreign DNA fragments (genes) that have been inserted into them and then propagated. Usually put into cells to make the desired protein.
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Gene Expression Beta Lactamase –Ampicillin resistance Green Fluorescent Protein (GFP) –Aequorea victoria jellyfish gene araC regulator protein –Regulates GFP transcription p BAD
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pGLO
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Bacterial Transformation Beta lactamase (ampicillin resistance) pGLO plasmids Bacterial chromosomal DNA Cell wall GFP Flagellum
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What is Transformation? Uptake of foreign DNA, often a circular plasmid. May involve bacteria or many eukaryotic types of cells. Process of copying genes of interest and making proteins from them. GFP Beta-lactamase Ampicillin Resistance
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Transformation Procedure Overview Day 1 Day 2
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Transcriptional Regulation Lactose operon Arabinose operon pGLO plasmid
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Transcriptional Regulation BAD araC BAD RNA Polymerase Effector (Arabinose) araC BAD ara Operon RNA Polymerase ZYA ZYA LacI Effector (Lactose) ZYA LacI lac Operon p BAD
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Gene Regulation RNA Polymerase araC ara GFP Operon GFP Gene araC GFP Gene araC GFP Gene Effector (Arabinose) BAD araC BAD RNA Polymerase Effector (Arabinose) araC BAD ara Operon p BAD
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Methods of Transformation Electroporation –Electrical shock makes cell membranes permeable to DNA Calcium Chloride/Heat-Shock –Chemically-competent cells uptake DNA after heat shock
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Transformation Procedure Suspend bacterial colonies in Transformation solution Add pGLO plasmid DNA Place tubes on ice Heat-shock at 42°C and place on ice Incubate with nutrient broth Streak plates
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Reasons for Performing Each Transformation Step? 1.Transformation solution = CaCI 2 Positive charge of Ca ++ ions shields negative charge of DNA phosphates Ca ++ O CH 2 O PO O O Base CH 2 O P O O O Base OH Sugar O Ca ++
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Why Perform Each Transformation Step? 2. Incubate on ice slows fluid cell membrane 3. Heat-shock Increases permeability of membranes 4. Nutrient broth incubation Allows beta-lactamase expression Beta-lactamase (ampicillin resistance) Cell wall GFP
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What is Nutrient Broth? Luria-Bertani (LB) broth Medium that contains nutrients for bacterial growth and gene expression –Carbohydrates –Amino acids –Nucleotides –Salts –Vitamins We will have THREE Types of Agar Plates: -LB only -LB + Amp -LB + Amp + Arabinose
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Grow? Glow? Follow protocol On which plates will colonies grow ? Which colonies will glow ?
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Laboratory Quick Guide
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Volume Measurement
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Aequorea victoria- a jellyfish
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