DNA by Hannah

DNA stands for Deoxyribonucleic Acid. It is the genetic material in all living things that makes up their genes. Multiple scientists – Fredrick Griffith, Oswald Avery, Alfred Hershey, and Martha Case – discovered that DNA was in fact the hereditary material and not protein, which was widely accepted at the time. The structure of DNA, however, was still unknown. Some key figures in the discovery of the structure of DNA were Rosalind Franklin, Erwin Chargaff, and Watson and Crick. The combination of all their experiments results in the structure of DNA. They discovered that the structure of the molecule is a double helix and the sugar-phosphate strands are held together by nucleotides. 

Each nucleotide has three parts: deoxyribose, a phosphate (PO₄) group, and an organic base. There are four different kinds of bases: Adenine, Thymine, Guanine, and Cytosine. These bases are split in two groups: purines and pyrimidines. The purines, or larger bases, are Adenine and Guanine. The pyrimidines, or smaller bases, are Thymine and Cytosine. Chargaff’s rules states that DNA molecules always have equal amounts of pyrimidines and purines. The bases are always paired with each other in the same way as well (A = T, & G = C). Hydrogen bonds are then formed between the base pairs. 

DNA copies itself through a process called DNA Replication. During this process, the DNA strands unwind, an enzyme primes the strand for replication, another enzyme builds the strands, and then the new strands are rewound. The enzymes involved in this process are helicase (unwinds strands), DNA polymerase III (adds complementary nucleotides to the strands), primase (synthesizes a primer to begin the construction of the new strand), DNA polymerase I (removes primer and fills in the gap left), and DNA ligase (joins the ends of the newly synthesized segments of DNA). During the process of DNA replication mistakes can occur. These mistakes are called mutations. A mutation is a change in the content of the genetic message. A recombination is a change in position of a portion of the genetic message.

It is very important that we know about DNA for multiple reasons. First, so we can better understand the causes of some diseases and create better preventative medicines. Next, it is important to know how a disease is passed on in order to trace it or predict the chances of someone having it. It is also important to know how our DNA may be affected by certain environmental factors, or how our choices could affect our children’s DNA. How much more do you think future generations will know about DNA than we do now? Do you think there will be more mutations? Why?

Here are a few interesting facts about DNA:

·         “Every human being shares 99% of their DNA with every other human.”

·         “If you put all the DNA molecules in your body end to end, the DNA would reach from the Earth to the Sun and back over 600 times.”

·         “DNA is found inside every cell in our body (apart from red blood cells), and each cell contains roughly 2 meters of DNA.”