Macromolecules

All Biomolecules have certain functions and these molecules all have a unique structure which is why they function in these ways. These molecules are known collectively as macromolecules, these molecules are grouped into four main categories which each have there own structure. These structures are the key to the macromolecules functions as each of them do a specific task in the body.

Macromolecules are grouped into carbohydrates, nucleic acids, proteins, and lipids. In most cases macromolecules are polymers, which is a long molecule which are made by linking together a large number of small, similar compounds called monomers. Polymers are formed by a dehydration reaction, this happens by the -OH group being removed from one monomer, and a
Carbohydrates have a general formula of (CH2O)n, where n is the number of carbon atoms. These carbohydrates contain a lot of carbon-hydrogen bonds, which releases energy when oxidation occurs, as carbohydrates are well suited for energy storage. Sugars are some of the most important energy sources and they exist in several different forms, such as monosaccharides, disaccharides and polysaccharides. Monosaccharides are the simplest of carbohydrates, they may contain as few as three carbons but the ones that have a key role in energy storage have six carbons. Disaccharides serve as transport molecules in plants and provide nutrition in animals; they are used by plants for transporting glucose around the plant as disaccharides are not easily metabolised, but disaccharides are usually consumed by humans and animals. Polysaccharides provide energy storage, such as starch consists entirely of α-glucose molecules linked in a long chain. Cellulose is a structural polysaccharide which also consists of glucose linked in long chains, but these molecules are β-glucose. Carbohydrates are used as a source of energy for processes in the body such as muscle movement (Raven et al
The specific order of amino acids determines the proteins structure and function. The amino and acid carboxyl group go through a dehydration reaction to form a peptide bond which joins the amino acids together to form proteins. Proteins have many different functions which are placed into seven categories; Enzyme catalysis, Support, Defence, Motion, Transport, Regulation and Storage. Enzyme catalysis is when enzymes which are globular proteins with a three-dimensional shape that fit around some molecules to facilitate chemical reactions (Raven et al 2008). Support proteins fibres play a structural role, these fibres include keratin in hair fibrin in blood clots and collagen which forms the matrix of skin, ligaments, tendons, and bones, and is the most abundant protein in a vertebrate body (Raven et al 2008). Defence proteins are globular and use there shape to "recognise" foreign microbes and cancer cells, these cell-surface receptors are from the core of the body's endocrine and immune system (Raven et al 2008). Muscles contract through the sliding motion of two kinds of protein filaments: actin and myosin (Raven et al 2008). A variety of globular proteins transport small molecules and ions. The transport protein Haemoglobin, for example, transports oxygen in the blood stream (Raven et al 2008). Small proteins called