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Published byEgbert Craig Modified over 9 years ago
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Restriction Nucleases Cut at specific recognition sequence Fragments with same cohesive ends can be joined
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Gel Electrophoresis DNA molecules separated by size DNA detected by ethidium bromide staining or by prior incorporation of radioisotope
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Nucleic Acid Hybridization Complementary strands of DNA or RNA can renature Labeled single stranded DNA probe often used to detect specific DNA or RNA molecules in a sample
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Generating Labeled Probe Random primers annealed to DNA fragment DNA polymerase incorporates labeled nucleotides
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At higher temperatures only identical sequences hybridize At lower temperatures related sequences also hybridize Stringency Of Hybridization
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Southern And Northern Blotting Complex mixture of DNA or RNA separated by electrophoresis Transferred to membrane and hybridized with labeled probe
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DNA Cloning In Bacteria Insert DNA fragment into bacterial plasmid Propagate recombinant plasmid in bacteria
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DNA Library Collection of cloned DNA fragments Usually are set of recombinant plasmids contained in bacteria Each bacterial colony contains one cloned fragment
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Genomic DNA Library Contains entire genome of a particular individual DNA fragments generated by restriction nuclease
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cDNA Library Contains only DNA sequences that are transcribed into mRNA cDNA generated from mRNA using reverse transcriptase Different library generated from every cell type
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cDNA Vs. Genomic DNA Clones cDNA clones useful for deducing protein sequences Genomic clones useful for obtaining noncoding and total genome sequences Library screening to select clones of interest
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Polymerase Chain Reaction Oligonucleotides complementary to opposite ends of sequence to be amplified serve as primers for DNA polymerization
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DNA Amplification Using PCR Repeated cycles of denaturation, annealing, and DNA synthesis
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DNA Cloning By PCR Genomic DNA clones: PCR amplification of segment between primers cDNA clones: Reverse transcription of mRNA followed by PCR
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PCR In Forensic Analysis PCR using primers that flank a VNTR
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Genetic fingerprint by analyzing several VNTRs
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Genetic Test Using Allele- Specific Oligonucleotides A probe S probe P1P2C1C2C3C4 A allele S allele -CCTGAGGAG- -CCTGTGGAG- -globin gene PCR Primer PCR, gel electrophoresis, hybridization
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Hybridization Using Microarrays Slide with array of DNA probes Genomic DNA or mRNA sample (mRNA→cDNA) DNA sample labeled with fluorescent dye and hybridized Fluorescence measured
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Gene Expression Patterns In Cancer Cells Characteristic expression patterns in different types of cancer cells
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Dideoxy DNA Sequencing Each reaction includes one of four ddNTPs ddNTPs block chain growth
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Fragment sizes indicate positions of each nucleotide
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Automated Sequencing Of DNA One reaction with four fluorescent labeled ddNTPs
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Sequencing Genomes Shotgun method: Generate several genomic libraries with different size inserts Perform sequencing reactions on millions of genomic clones Establish order on chromosome based on sequence overlaps
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Highly Parallel Sequencing Clonal amplification of DNA fragments on solid surface High density array of clonal DNA clusters Sample preparation
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nucleotide addition imaging by fluorescence or chemiluminescence to detect nucleotide incorporation at each DNA cluster Sequencing by synthesis: repeated cycles
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Finding DNA Sequences That Encode Proteins –Search open reading frames, splice sites, regulatory elements –Compare to cDNA sequence database –Compare to other species From genome: From cDNA: usually one open reading frame
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Antibodies to Detect Proteins Antibodies are produced by immune system Billions of forms bind to different antigens Primary antibody recognizes specific antigen; secondary antibody used for detection
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Western Blotting Complex mixture of proteins separated by polyacrylamide- gel electrophoresis and transferred to membrane Antibody used to detect specific protein
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Producing Proteins Insert gene into expression vector adjacent to strong promoter Introduce into cells Purify overexpressed protein
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Locate disease genes using physical markers Physical markers have known locations and are polymorphic Examine relationship between physical markers and disease Co-inheritance indicates nearby location Linkage Analysis
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Inheritance Patterns Simple mendelian Autosomal dominant Autosomal recessive X-linked recessive Complex genetic diseases: many common diseases, risk dependent upon multiple genes and environment
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Genome-Wide Association Studies Compare frequency of SNP alleles in healthy and disease populations SNP allele with higher frequency in disease population indicates genetic risk factor
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Identification of Genetic Risk Factors age-related macular degeneration asthma bipolar disorder coronary artery disease Crohn’s disease diabetes-type 1 diabetes-type 2 obesity prostate cancer rheumatoid arthritis
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Gene Targeting In Mice
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RNA Interference Turn off gene expression Introduce dsRNA to degrade specific mRNA
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Genome Engineering Using CRISPR-Cas9 Targeted genome editing Introduce Cas9 (nuclease) and gRNA for genomic target DS break, repaired by NHEJ, usually inactivates gene Introduction of repair template allows precise editing
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Generation of Mutant Organisms using CRISPR/Cas9
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