Thinking Fast and Slow

The Structure of DNA Do you recognize this molecule? This is DNA, or deoxyribonucleic acid. By the end of this blog, you will be able to identify the key structural features of DNA, as well as describe the importance of those features for function. We will look at different representations of the DNA molecule to better view certain details, but all views represent this same structure. Inside the cell, you will most commonly find double- stranded DNA, in which two strands intertwine to form a double helix. The most common form of the DNA double helix, which is what we will discuss here, is also called B-form DNA. Now, let's move to a more simplified representation of DNA to discuss the details. We can unwind the double helix like this so that we can see the chemical structure inside. Each strand is a polynucleotide, meaning the strand is made up of many individual units called nucleotides. A nucleotide has three components, the fiv...

In Biology, "double helix" is a term used to describe the structure of DNA. A DNA double helix consists of two spiral chains of deoxyribonucleic acid. The shape is similar to that of a spiral staircase. DNA is nucleic acid composed of nitrogenous bases (adenine, cytosine, guanine and thymine), a five carbon sugar (deoxyribose), and phosphate molecules. The nucleotide bases of DNA represent the stair steps of tyhe staircase, and the deoxyribose and phosphate molecules from the sides of the staircase. Why is DNA twisted? DNA is coiled into chromosomes and tightly packed in the nucleus of our cells. The twisting aspect of DNA is a result of interactions between the molecules that make up DNA and water (H2O). The nitrogenous base that comprise the steps of twisted staircase are held together by hydrogen bonds. Adenine is bonded with thymine (A-T) and guanine pairs with cytosine (G-C). These nitrogenous bases are hydrophobic, meaning that they lack an affinity for water...