Gregor Mendel, an Austrian monk, is known as the father of genetics. His experiments laid down the foundation for future scientists’ research genetics. Mendel’s experiments with pea plants demonstrated that a certain strain of peas bred true- tall plants produced tall offspring and short plants produced short offspring. Mendel proceeded to produce a hybrid plant by mixing tall and short plants together. The offspring of these hybrids were tall, however, when Mendel continued cross breeding the offspring he found that 3/4 of their offspring were tall and 1/4 were short. It was concluded that adults possess two sets of genes - one contributed by each parent. The play between the genes determines the offspring’s characteristics. Mendel continued and determined that genes can be dominant or recessive. When one trait is produced, the gene is said to be dominant. He also showed that genes could be recessive meaning they don’t show up on all offspring and may in fact skip a generation. His experiments became known as the Law of Dominance and the Law of Segregation. His findings were published in 1865 but it wasn’t until the early 1900s when biologists gave them credence, realizing the factors Mendel spoke of in his experiments were actually chromosomes.
Genetic material is composed of DNA and passed from one generation to the next. It is referred to as the “code of life” because it links generations together. After years of research scientists concluded that DNA “ is a large molecule that is built from a large number of similar building blocks”(6). It looks like a ladder with two sides and a number of rungs. The sides are twisted around each other with 10 rungs for each twist or turn. It is described as a double helix and in 1953 two biologists, James Watson and Francis Crick published their visual explanation of its appearance. Their explanation of this structure explained how DNA copies or replicates itself through cell division. During replication the two strands of DNA separate and synthesize a new complementary strand with the existing bases, sugars and phosphates. This process produces two new strands of DNA. Sometimes a mistake occurs during the replication process. This mistake makes a permanent change in the structure of the DNA and as a result of this, a mutation develops. Some mutations only have a minor effect, however some may have a major effect depending upon the way in which the protein is changed. These finding have led geneticists to probe into human disease through research and more. Using Watson and Crick’s explanation scientists were first able to begin unraveling the genetic code as a basis for future research.
DNA is made of three substances: Phosphate (P), a sugar called deoxyribose (D), and a third substance, which is a base. The first two substances make up the sides of the ladder. There are four differently shaped bases, which make up the rungs of the ladder: Adenine (A), Cytosine (C), Guanine (G) and Thymine (T). A and G are “long” bases and T and C are “short” bases. A bases are always paired with T bases and C are always paired with G bases. The pairs of bases are held together by hydrogen bonds, but in order to stay bonded the base shapes have to fit together like puzzle pieces (6). The way in which the bases are sequenced makes up the DNA code. The cell uses this unique code to control protein synthesis, which determines our characteristics because many proteins are enzymes that control our biochemistry.