my teacher,the hour
June 5, 1996
Genetics is the study of how physical, biochemical, and behavioral traits are
transmitted from parents to their offspring. The science of genetics started in 1900, when
the work of Gregor Mendel was discovered. Mendel described the inheritence patterns of
garden peas. He suggested after researching his pea-plant experiment that each parent has
pairs of units but contributes only one unit for to each pair of its offspring. These units
were later given the name genes.
Every cell comes from a division of a cell that is already existing. For example, all
cells that make up a human being are derived from divisions of a single cell, called the
Chromosomes usually occur in pairs and are various sized and shapes. The
members of each pair ar called homologues. The human body contains 23 pairs of
chromosomes, while the fruit fly contains four pairs. Every chromosome in a cell is
known to contain many genes and each gene is located at a particular site, or locus, on the
Theodore Oswald Avery a Canadian-born Physician nad bacteriologist who is
known for wondrous discoveries in the genetic field. He earned his medical degree at
Columbia University’s College of Physicians and Surgeons. He was the first to show that
the agent responsible for transferring genetic information was not aprotein , as what was
then thought in his time, but the nucleic acid DNA. Avery and his co-workers extracted a
substance from a type of bacterium with a smooth surfac and introduced the substance
into a rough surfaced type of bacterium.When the rough surfaced bacteria was
transformed into the smooth-surfaced type, he knew the substance that had been extracted
contained the gene that coded ford the smooth surface. He and his team purified theis
substance and found it was pure DNA.
Avery published the results of this research in
The genetic material is deoxyribonucleic acid, or simply put, DNA. DNA is a molecule
that forms a the “backbone of a chromosome. Since the continuous molecule is is long and
thin the genes are a part of that molecule. Because the DNA is a chain of minute subunits
called nucleotide bases, each gene includes many bases. In the chain four different bases
exist- adenine, cytosine, guanine, and thymine.
Their order in each particular gene
determines its properties. Genes puat out their effects through the molecules that they
produce. The immediate products of a gene are molecules of ribonucleic acid, (RNA).
These are virtually the same as DNA except that RNA has uracil as a base instead of
thymine. RNA molecules of some genes play a certain role in the metabolism of the
organism, but most of them are used to make protein. Proteins are chains of subunits
called amino acids.
The sequenceof these amino acids in a protein dictates whether or not
it will become part of the structure of the organism, or whether it will become an enzyme
for promoting a certain chemical reaction.
Genetic Engineering is the method of changing the inherited characteristics of an organism
in a predetermined way by altering its genetic material. This is often done to cause
microorganisms, like a bacteria or a virus, or to synthesize increased yields of compounds,
to form entirely new compounds to form completely new compounds. This process is also
used to adapt to different environments. Another is called recombinant DNA
technologym including gene therapy which is the supply of a functioal gene to a person
with a genetic disorder or with other diseases such as AIDS or cancer.
Genetic Engineering involves the process of manipulating DNA.
enzymes are very important tools in this process. The restriction enzymes are produced y
various species of bacteria, and they can recognize a particular sequence of the chain of
chemical units called nucleotide bases, which make up the DNA molecule and cut the
DNA at that location. Small bits of DNA generated in this way can be joined using other
enzymes called ligases. Restriction enzymes and ligases therefore allow the specific
cutting and reassembling of picies of DNA. Vectors are also important in the
manipulation of DNA. These vectors are pieces of DNA that can self-replicate by
themselves the DNA, making this .