13-2: Manipulating DNA Biology 2

Until very recently breeders could not change the DNA of the plants/animals they were breeding Scientists use DNA structure and chemical properties to extract, cut into pieces, identify and copy DNA Introduction

GENETIC ENGINEERING: process of making changes in the DNA code of living organisms You take the “code” out that you want Read and change the code Then put it back Tools of Molecular Biology

DNA extraction: cells are cut open, and DNA is separated from the other parts Have to cut cells and nucleus open to get DNA Tools of Molecular Biology

Cutting DNA: DNA is cut into smaller parts using restriction enzymes to cut specific parts – RESTRICTION ENZYMES: enzyme that cuts DNA at a specific sequence of nucleotides Tools of Molecular Biology

Separating DNA: Gel electrophoresis is used to separate DNA pieces – GEL ELECTROPHORESIS: procedure used to separate and analyze DNA fragments by placing a mixture of DNA fragments at one end of a porous gel and applying an electrical voltage to the gel DNA is placed at one end, and electricity is used to separate pieces Tools of Molecular Biology

Scientists use “colored” bases to copy pieces of DNA When a “colored” base of DNA is added, replication is stopped – The “colored” bases show up on the electrophoresis (like previous picture!) The colors on electrophoresis tell scientists the exact order of bases on the DNA Using the DNA sequence

DNA can be changed in lots of ways Short sections can be made using DNA synthesizers RECOMBINANT DNA: DNA produced by combining DNA from different sources – Recombinant DNA can connect 2 different species DNA together Using the DNA sequence

In order to study genes, biologists need to make many copies Polymerase Chain Reaction (PCR): technique that allows molecular biologists to make many copies of a particular gene – PCR Works like a copy machine making LOTS of copies Using the DNA sequence

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