2 What are plasmids? Small, circular DNA molecules (Found in bacteria)They are separate from the bacterial chromosome
3 Why are plasmids useful? They are used to manipulate genes in the labThey are smallContain genes useful to the bacteriaAnd, are easily taken up by bacterial cellsWhen they are taken up they are called vectorsWhat happens when the bacterial cell replicates its chromosome?It also replicates the plasmid DNA(including any foreign DNA as well)vector A DNA carrier that move genes from one cell to another
4 What does cutting and pasting of DNA mean? Enzymes are involvede.g., A T C GFor cutting, what are they called?Restriction enzymesThey recognize specific sequence of: A T C GHundreds have been isolated from bacteriaFor pasting, what are they called?DNA ligasesIts the last step to make recombinant DNAThey bind cut ends back together(by covalent bonds between adjacent nucleotides)
5 So, this cutting and pasting of DNA is used to: Cut gene sequence of interest (e.g., from human DNA)Enzyme name?Cut a plasmid (from a bacterium)Enzyme name?Create a recombinant DNA moleculeBy using the plasmidAnd ‘pasting’ a human gene sequence into itEnzyme name?
6 Polymerase Chain Reaction Or PCRPCR is a techniqueIn which any segment of DNA can be copiedQuickly and preciselyWhy is it so important?Use minute amounts of blood or other tissueTo generate enough DNA for analysise.g., DNA from the follicle of ONE stand of hair
7 How does PCR work? Make a mixture of: the DNA sample, some nucleotides,an enzyme, DNA polymeraseTreat the mixture to:cycles of heatingAllows separation of DNA strandscycles of coolingAllows DNA strands to re-form duplexesDNA Replication occurs during cooling cycle
8 In each cycle, the DNA is DOUBLED How many copies of DNA after each cycle?How many copies after a 5th cycle?___1st cycleWithin a few hours:___2nd cyclePCR can generate billions of copiesFrom a SINGLE DNA molecule___3rd cycle___4th cycleEnough to do extensive analyses
9 The Human Genome Project What was the goal of HGP?To determine the nucleotide sequence all the DNAIn any given human cellTo identify the location & sequence of every geneWhat was discovered?Our DNA contains ~ 2.9 billion nucleotide pairsAbout 25,000 genesThere is a LOT of DNA that isn’t made up of genesAbout 97% is non-coding DNA
10 Learning check1. Why is only the slightest trace of DNA at a crime scene often sufficient for forensic analysis?2. A carrier that moves DNA from one cell to another, such as a plasmid, is called a ________3. What features of a DNA fragment causes it to move through a gel during electrophoresis?Its nucleotide sequenceThe hydrogen bonds between its base pairsIts double helix shapeThe electrical charges of its phosphate groups
11 4. A paleontologist has recovered a bit of organic 4. A paleontologist has recovered a bit of organic material from the 400 year old preserved skin of an extinct dodo. She would like to compare DNA from the sample with DNA from living birds. The most useful method for increasing the amount of dodo DNA available for testing is __________5. Why is golden rice pale yellow in color?aIt is rich in chlorophyll a.bIt is nutrient-poor.cIt is rich in beta-carotene.dIt is rich in chlorophyll b.eIt is rich in phycobilins.
12 What does this figure show? 24731865What does each ‘band’ consist of?