Chapter 13 2 MANIPULATING DNA Scientists are able

Chapter 13. 2 MANIPULATING DNA

Scientists are able to change DNA molecules now. They can take DNA from cells, cut DNA into smaller pieces, identify the sequence of bases in a DNA molecule, and make many copies of that DNA.

The Tools of Molecular Biology Genetic Engineering is the process of making changes in DNA.

DNA Extraction DNA can be extracted (taken out of a cell) by breaking the cells open and then separating the DNA from the other parts of the cell.

Cutting DNA Restriction enzymes are using to cut DNA at a specific place. It is able to recognize a set of bases and cut at a specific spot.

Separating DNA One procedure for separating DNA is called gel electrophoresis. This is when mixed and cut DNA is place in wells at the end of a porous gel substance. An electric charge is applied to the gel. This charge will pull DNA toward the opposite end (DNA is negatively charged, so when the charge is there it will move to the positive end). The smaller DNA pieces move faster and farther. Gel electrophoresis is very important in comparing genomes (genes from different species) or different individuals of the same species.

Using the DNA Sequence Knowing the specific DNA sequence is important for studying specific genes, to compare them with other organisms, and to discover functions of specific genes and gene combinations.

Reading the Sequence Scientists are able to determine the order of bases in DNA. To do this they take a single stranded DNA molecule and add it to a test tube with DNA polymerase and the 4 bases (A, T, G, and C). To figure out which base is which, the bases added to the test tube has a chemical dye attached to it. They then have different lengths of DNA and are able to run them on gel electrophoresis and figure out the order.

Cutting and Pasting Short sequences of DNA can be put together using a lab machine called DNA synthesizers. This allows scientists to cut DNA from one organism and paste it into the DNA of another organism. This is called recombinant DNA.

Making Copies There are times when scientists need to make several copies of a gene. They use something called polymerase chain reaction (PCR)