After passing through the cornea, light travels through the pupil (the black dot in the middle of the eye). The iris—the circular<span>, colored area of the eye that surrounds the pupil—controls the amount of light that enters the eye.</span>
DNA is composed of nucleotides, which are composed of three parts:
1. A five carbon carbohydrate (pentose)
Pentose is classified as a monosaccharide (simple carbohydrate), and its molecular formula is represented by
. They are water soluble molecules with sweet taste. Monosaccharides may have from three carbon atoms (trioses) to six (hexoses). In DNA is present pentose (5 carbon atoms)
2. A nitrogenous base
Nitrogenous bases are ring-shaped compounds that contain nitrogen in their molecular structure. They are classified into two groups: purines and pyrimidines
The purine bases are adenine (A) and guanine (G). They are larger and contain more than one ring in their structure,.
The pyrimidines, cytosine (C), uracil (U) and thymine (T), are smaller and composed of a single ring.
3. One or more phosphate groups
A phosphate consists of a trivalent anion that contains one phosphorus atom and four oxygen atoms. Its molecular formula is expressed by
.
Population and nutrients, This is because if you have a large population then you must need a certain amount of nutrients to suit the population