2 The chemistry of life
2.1 Overview
Introduction DUMMY
In this chapter we will study the molecular structure and biological functions of key molecules
important to life. We will study the chemistry of proteins, carbohydrates, lipids, vitamins and
nucleic acids and will learn the role of each nutrient class in plant and animal life. We will
also learn how our diet allows us to obtain sufficient quantities of each of these nutrients.Key concepts- Organic molecules always contain carbon (C), and usually also contain hydrogen (H)
and oxygen (O). Some important organic molecules also contain nitrogen (N), phos-
phorous (P), sulfur (S), iron (Fe) and other elements. - Water (H 2 O) is an inorganic compound made up of two H and one O. Water helps with
temperature regulation, form and support, transport and lubrication and is a medium
for chemical reactions. - Minerals are required as part of a healthy diet. A deficit in essential minerals results in
deficiency diseases in plants and animals. - Fertilizers are a way that essential nutrients can be added to the soil to improve plant
growth. - Carbohydrates are made up of C, H and O. They can be in the form of monosaccha-
rides (single sugars), disaccharides (double sugars) or polysaccharides (many sugars),
and are an important energy source for plants and animals. - Lipids are made up of C, H and O. Triglycerides are a type of lipid that contains glycerol
and three fatty acid chains. Cholesterol, another type of lipid, can increase the risk of
heart disease. - Proteins are made up of C, H, O, N, and some have P, S and Fe. Proteins consist of
a long chain of amino acids that fold into a very specific three-dimensional structure.
Proteins are an important building block in plants and animals and play a role in the
immune system and in cell communication. - Enzymes are a type of protein that act as a biological catalyst to speed up reactions.
They work by a ”lock and key” mechanism and are affected by temperature and pH. - Nucleic acids such as DNA and RNA are made of C, H, O, N and P. DNA contains
the genetic information for heredity, and RNA has the instructions on how to make
protein. - Vitamins are important organic molecules that must be obtained in the diet. They
often help enzymes to work properly, or act in growth or differentiation.
In order to understand the chemistry of living systems, it is important to understand how all
living systems are arranged from the smallest unit (atomic scale) to the largest unit (ecosys-
tems). A simple way to describe the levels of organisation of livings things can be given as
follows:24 2.1. Overview