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 li

The genetic code consists of 64 codons. However, since these codons order only some 20 amino acids, most, if not all, of the amino acids can be ordered by more than one of them. For example, the mRNA codons UGU and UGC both order cysteine. Because mRNA is a reverse copy of DNA the genetic code for cysteine is ACA or ACG. Some codons may act only to signal a halt to protein synthesis. Since code transmission from DNA to mRNA is extremely precise, any error in the code affects protein synthesis. If the error is serious enough, it eventually affects some body trait or feature. In this study, DNA was extracted from the bacterium Escherichia coli and then some of its physical properties were studied.

The DNA extraction was completed in one session of study. First, 5.0 ml. of E.coli suspension medium was placed in a measuring cup and added to the tube of freeze-dried E.coli. The tube was then capped very tightly and shook gently until the bacteria went into the suspension. Then, 1.0 ml. of sodium dodecyl sulfate (SDS) was added to the E.coli suspension. The tube was then capped and was rotated gently for over a period of five minutes. The suspension became more viscous as the bacteria was lysed. (Sodium dodecyl sulfate (SDS), a detergent used in laundry products, removes the lipids from E.coli cell walls. When the cell walls are damaged, the cells lyse, releasing the contents of into the E.cole suspension medium.) The tube was placed for 30 minutes in a hot water bath preheated to 60-65 degrees C. The lysate was removed from the water bath and was allowed to cool until it reached room temperature. With a pipet, the cold ethanol was added to the spooling tube, while

Some common words found in the essay are:
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Approximate Word count = 1126
Approximate Pages = 5 (250 words per page double spaced)