Biology » The Chemistry of Life » Molecules For Life

The Chemistry of Life

Introduction to the Chemistry of Life

In this lesson and the next few, 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.

  • Organic molecules always contain carbon (C), and usually also contain hydrogen (H) and oxygen (O). Some important organic molecules also contain nitrogen (N), phosphorous (P), sulfur (S), iron (Fe) and other elements.
  • Water (H2O) 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 monosaccharides (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 (ecosystems). A simple way to describe the levels of organisation of livings things can be given as follows:

atom \(→\) molecule \(→\) cell \(→\) tissue \(→\) organ \(→\) organism \(→\) ecosystem

The video below describes the levels of organisation of livings things.

Video: Biological Levels

The Amoeba Sisters video below takes you through the biological levels of organization: cells, tissues, organs, organ systems, organism, population, community, ecosystem, biome, biosphere.

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