The Roles and Functions of DNA
DNA is a double helix molecule that contains information that is used to make up a person’s body. DNA controls every aspect of a person’s body from their eye and hair colour, height, and other features. It is a chain of nucleotide units consisting of a nitrogenous base, a deoxyribose sugar and a phosphate the chain is called a polynucleotide and two strands of polynucleotide wrap around each other to make a double helix. The two strands of the helix run in opposite directions 1 up and 1 down. In DNA, the pyramidines are cytosine and thymine and the purines are guanine and adenine. Adenine and Thymine are bonded with two hydrogen bonds and cytosine and guanine are bonded with three hydrogen bonds. In DNA genes contain the codes for making polypeptides which combine with each other to make proteins and enzymes this is done by a code of the bases of DNA called the triplet code this is when three bases are used to create amino acids. There are 64 possible combinations because there are four different bases so some amino acids have more than one code as there are only 20 amino acids in the human body.
DNA replication is semi-conservative. The two strands are separated by an enzyme called Helicase and both become templates for new DNA. Each strand then attracts new organic bases to the ones already present. Another enzyme called DNA polymerase holds the amino acids in place, while the sugar-phosphate back-bone is formed. One final enzyme called ligase fixes any broken bits of the DNA together.
The function of DNA the function of DNA is to allow genetic information to pass from generation to generation without alteration. The only bonds between the strands are hydrogen bonds which allow for easy replication and protein synthesis.
The structure of DNA after the double helix structure is as follows. The double helix combines with proteins the coils itself up tightly and then the coils fold to form loops which make the chromosome held together in the centre by a centromere.
DNA replication happens in two ways, firstly in mitosis the DNA splits into its two separate strands and divides by a semi-conservative method the rest of the mitosis cycle is in four stages, the first