Why Living Things Are the Size They Are -- And None Other

Ever Since The domestication of plants and animals began some 15,000 years ago, humans have wondered why and how the characteristic traits of parents are transmitted to their offspring. The earliest theories put forward by Greek philosophers were based on conjecture and superstition. These theories were acceptable until modern genetics entered the arena in the late 19th century, following the experiments of Austrian monk Gregor Mendel.(Allen, 107)

Genetics is a branch of biology that deals with genes and their inheritance. Genes may be considered to be pieces of biological information that parents pass to their offspring and are present in all living organisms. All things in nature—such as a person's height, the color of a rabbit's fur coat, the shape of a leaf, and the taste of a fruit—are dictated by genes.

The major challenge facing geneticists is understanding how all this information is stored in cells, how is it transmitted from one generation to the next, and why a slight variation in genetic code changes an organism's growth or even causes disease and death. Modern geneticists are beginning to understand genetic variability and heredity while also participating in and benefiting from rapid progress in other fields, such as molecular biology, biochemistry, and cell biology. Genetic engineering, a branch of modern genetics, is a technique used by geneticists to modify the very genes of an organism. Although genetic engineering has been a boon to the advancement of medicine and science, it has also been covered in the news media due to various ethical and legal issues. (Cohen,7)

DNA and RNA

Although all humans have the same set of genes, a slight variation in alleles can make each person genetically unique. The basic vehicle for transmitting genes from one generation to the next is DNA, also known as deoxyribonucleic acid. DNA is stored as a supercoiled molecule called a chromosome found inside the nuclei of cells. Segments of DNA that contain all the information required for synthesis of a product (polypeptide chain or RNA molecule) and that include both the coding and noncoding sequences are called genes. Genes dictate the synthesis of proteins, which carry out all life's functions in a living cell.(Bjorklund,163)

Today, genetics is playing an increasing role not only in healthcare, but also in other areas of society. Fruits have been genetically modified so that they taste and look better, and can last longer. Certain fruits and vegetables are being modified to carry vaccinations inside them so that in the near future, getting vaccinated against hepatitis B would simply be a matter of eating a genetically altered potato. Additionally, these vaccine fruits and vegetables could be transported to remote areas in Third World countries that may lack health personnel to administer vaccine injections. (Cohen,7)

Fig. 1. The repair of DSBs by NHEJ requires the coordinated assembly of damage-responsive proteins and phosphorylation events at the damage site. It is believed that Ku first binds to the DNA ends, translocates inward, and recruits ...