Biology  5/e   Raven/Johnson
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Structure of DNA: DNA is a double helix formed from two strands of nucleotides. Each strand is made up of deoxyribose sugar molecules linked by phosphodiester bonds and bases attached to each sugar molecule. The strands are linked, ladder fashion, by hydrogen bonds between the bases of each strand. The base, cytosine, pairs with guanine while the base, thymine, pairs with adenine. The resulting "ladder" is twisted into a helix.

Enzymes and enzyme activity: Enzymes are protein catalysts of specific reactions. In order to function, an enzyme must physically conform to the shape of the substrate.

Stages of a genetic engineering experiment: The four stages of genetic engineering experiments are: DNA cleavage, production of recombinant DNA, cloning, and screening.

The polymerase chain reaction (PCR): The three steps of PCR are: denaturation, annealing of primers, and primer extension.

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