Enzymes for DNA Manipulation Enzymes for DNA Manipulation The enzymes available to the molecular biologist fall into four broad categories Enzymes for DNA Manipulation ID: 1045568
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1. Studying DNADr. Hilal AY
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3. Enzymes for DNA Manipulation
4. Enzymes for DNA Manipulation
5. The enzymes available to the molecular biologist fall into four broad categories:Enzymes for DNA Manipulation
6. DNA Polymerases An enzyme that synthesizes DNA is called a DNA polymerase, and one that copies an existing DNA or RNA molecule is called a template-dependent DNA polymerase. A template-dependent DNA polymerase makes a new DNA polynucleotide whose sequence is dictated, via the base-pairing rules, by the sequence of nucleotides in the DNA or RNA molecule that is being copied.
7. DNA Polymerases The new polynucleotide is always synthesized in the 5ʹ → 3ʹ direction: DNA polymerases that make DNA in the other direction are unknown in nature.
8. DNA Polymerases An important feature of template-dependent DNA synthesis is that a DNA polymerase is unable to use an entirely single-stranded molecule as the template. In order to initiate DNA synthesis, there must be a short, double-stranded region to provide a 3ʹ-end onto which the enzyme will add new nucleotides.
9. In the test tube, a DNA-copying reaction is initiated by attaching to the template a short, synthetic oligonucleotide, usually about 20 nucleotides in length, which acts as a primer for DNA synthesis. At first glance, the need for a primer might appear to be an undesired complication in the use of DNA polymerases in recombinant DNA technology, but nothing could be further from the truth. Because annealing of the primer to the template depends on complementary base pairing, the position within the template molecule at which DNA copying is initiated can be specified by synthesizing a primer with the appropriate nucleotide sequence. DNA Polymerases
10. Features of template-dependent DNA polymerases used in molecular biology researchDNA Polymerases
11. Nucleases Restriction endonucleases enable DNA molecules to be cut at defined positions
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14. Gel electrophoresis is used to examine the results of a restriction digest
15. Gel electrophoresis is used to examine the results of a restriction digest
16. Ligases Ligases join DNA fragments together
17. End-modification enzymes
18. The Polymerase Chain Reaction (PCR)
19. Carrying out a PCR
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