Nucleic Acids And Protein Synthesis Outline Essay

Nucleic Acids And Protein Synthesis; Outline Essay, Research Paper

Nucleic Acids and Protein Synthesis

7-1 DNA

Cells “know” how to how to produce ATP, how to build cilia and centrioles, how

to produce membranes and enzymes.

A program, or code, in living cells must be able to duplicate itself quickly and

accurately and must also have a means of being decoded and put into effect.

The Genetic Code

Biologists call the program of the cell the genetic code. The work genetic refers

to anything that relates to heredity. The genetic code is the way in which cells store

program that they seem to pass from one generation to another.

Transformation

When a strain of information is passed to another, it is called transformation.

The Transforming Factor

DNA is the nucleic acid that stores and transmits the genetic information from

one generation of an organism to the next. DNA carries the genetic code.

Bacteriophages

Some virusus are known as bacteriophages which mean bacteria eaters.

Bacteriophages are composed of a DNA core and a protein coat. They attach themselves

to the surface of a bacterium and then inject a material into the bacterium. Once inside

the bacterium, the injected material begins to reproduce, making may copies of the

bacteriophage. Soon the bacterium bursts, and several hundred bacteriophages are

released to infect other cells. Because the material injected into the bacterium produces

new bacteriophages, it must contain the genetic code.

The Structure of DNA

DNA is a polymer formed from units called nucleotides. Each nucleotide is a

molecule make up of three basic parts: a 5-carbon sugar called deoxyribose, a phosphate

group, and a nitrogenous, or nitrogen-containing, base.

DNA contains four nitrogenous bases. Two of the nitrogenous bases, adenine and

guanine, belonging to a group of compounds known as purines. The remaining two,

cytosine and thymine, are known as pyrimidines.

Individual nucleotides are joined together to form a long chain.

X-Ray Evidence

Fibers that make up DNA are twisted, like the strands of a rope. Large groups of

molecules in the fiber are spaced out at regular intervals along the length of the

The Replcation of DNA

Because each of the two strands of the DNA double hehx has all the information,

by the mechanism of base pairing, to reconstruct the other half, the strands are said to

be complementary. There are four nitrogenous bases in DNA. Each strand of the double

helix of DNA serves as a template, or pattern, against which a new strand is made.

Before a cell divides, it must duplicate its DNA. This ensures that each resulting cell will

have a complete set of DNA molecules. This copying process is known as replication.

DNA replication, or DNA synthesis, is carried out by a series of enzymes. These

enzymes separate, or “unzip,” the two strands of the double helix, insert the

appropriate bases, and produce covalent sugar-phosphate links to extend the growing

DNA chains. The enzymes even “proofread” the bases that have been inserted to ensure

that they are paired correctly.

The unzipping occurs when the hydrogen bonds between the base pairs are

broken and the two strands of the molecule unwind. Each of the separated strands

serves as a template for the attachment of complementary bases. Two DNA molecules

identical to each other and to the original molecule are made.

7-2 RNA

The double helix structure explains how DNA can be replicated, or copied.

However, it does not explain how information is contained in the molecule or how that

information is put to good use. DNA contains a set of instructions that are coded in the

sequence, or order, of nucleotides. The first step in decoding that message is to copy

part of the sequence into RNA (ribonucleic acid). RNA is the nucleic acid that acts

as a messenger between DNA and the ribosomes and carries out the process by

which proteins are made from amino acids.

The Structure of RNA

RNA, like DNA, consists of a long chain of macromolecules made up of

nucleotides. Each nucleotide is made up of a 5-carbon sugar, a phosphate group, and

a nitrogenous base. The alternating sugars and phosphate groups form the backbone

of the RNA chain.

There are three major differences between RNA and DNA. The sugar in RNA is

ribose, whereas the sugar in DNA is deoxyribose. Another difierence between RNA

and DNA is that RNA consists of a single strand of nucleotides, although it can form

double-stranded sections by folding back on itself in loops. DNA, as you will recall, is

double-stranded. Lastly, the nitrogenous bases found in DNA are adenine, thymine,

cytosine, and guanine. RNA also contains adenine, cytosine, and guanine, but uracil

(toom-uh-sihl) is present instead of thymine. Like DNA, RNA follows the base

pairing rules. Adenine bonds to uracil, and

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