3s2+bio+essay+by+Samuel,+Nathanael+and+Kenneth+Loh

This is the bio essay of Samuel, Nathanael and Kenneth Loh DNA, or Deoxyriboenucleic Acid, is the control centre for the creation of life. It's existence within the chromosomes have guaranteed the continuation of life as we know it. Like how popular culture usually represents DNA, it looks like a ladder spun into a corkscrew except the sides aren't made up of wood or metal, it is made up of polynucleotide stands with hydrogen bonds in between. The structure in which the 'corkscrew ladder' forms is called the double helix.

Genes are segments of DNA that code for a functional mRNA or polypeptide. This is associated with proteins and packed into chromatin fibres and, finally, as chromosomes. Chromatin fibres when packed together form nucleosomes. Nucleosomes collectively form are the entire mitotic chromosome. The chromosome is normally in the shape of an "x" and the number of chromosomes varies from organism to organism.

The DNA molecule on its own is double-stranded, and each polynucleotide strand stands alongside each other. They are antiparallel, as they will run in opposite directions without direct contact, where the 5' (five prime) end (with a terminal phosphate group) runs in opposite direction with the 3' (three prime) end (with a terminal hydroxyl group).

If we take a look at one side of the double helix, we'll notice that it's actually made up of a strand of nucleotides bonded together by phosphorus bonds. if we unravel the double helix and place one side verticalled, we can say that it is made up of many nucleotides stacked one on top of another bonded by phosphorus molecules. Well if you ask what's actually getting bonded by the phosphorus molecules, it is actually pentose sugars. these sugars make up the 'vertical beam' of a ladder along with the phosphorus bonds. Also attached to these pentose sugars along the 'x' axis are nitrogenous bases namely : adenine (A), cytosine (C), thymine (T) and guanine (G). These bases are the ones which create the 'steps' on the ladder.

The adenine base pair in a DNA molecule's strand only binds to the thymine base pair in the adjacent strand via two hydrogen bonds, and cytosine bonds with guanine via three hydrogen bonds. These are referred to as complimentary base pairs. When a sequence is coded for by a messenger RNA (mRNA), adenine binds with uracil instead. Adenine and guanine are purines, meaning that they have a different structure than their respective complimentary pyrimidines thymine and cytosine, but link the DNA molecule together via hydrogen bonding between the complimentary pairs.

The messenger RNA carries the genetic sequence that codes for a particular protein from the nucleus to the cytoplasm. The transfer RNA matches amino acids to their codon. Ribosomes are formed by rRNA and proteins, which are the site of mRNA translation and protein synthesis. []