Extracting DNA From The Bacterium Escherichia Coli

Extracting DNA from the Bacterium Escherichia coli

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Introduction

Deoxyribonucleic acid is contained in all cells. The structure of DNA makes gene transmission possible. Since genes are segments of DNA, DNA must be able to make exact copies of itself to enable the next generation of cells to receive the same genes. The DNA molecule looks like a twisted ladder. Each "side" is a chain of alternating phosphate and deoxyribose sugar molecules. The "steps" are formed by bonded pairs of purine-pyrimidine bases. DNA contains four such bases the purines adenine (A) and guanine (G) and the pyrimidines cytosine (c) and thymine (T). The RNA molecule, markedly similar to DNA, usually consists of a single chain. The RNA chain contains ribose sugars instead of deoxyribose. In RNA, the pyrimidine uracil (U) replaces the thymine of DNA. DNA and RNA are made up of basic units called nucleotides. In DNA, each of these is composed of a phosphate, a deoxyribose sugar, and either A, T, G, or C. RNA nucleotides consist of a phosphate, a ribose sugar, and either A, U, G, or C.

Nucleotide chains in DNA wind around one another to form a complete twist, or gyre, every ten nucleotides along the molecule. The two chains are held fast by hydrogen bonds linking A to T and C to G A always pairs with T (or with U in RNA); C always pairs with G. Sequences of the paired bases are the foundation of the genetic code. Thus, a portion of a double-stranded DNA molecule might read: A-T C-G G-C T-A G-C C-...

Extracting DNA From The Bacterium Escherichia Coli

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