Biology Cell Structure And Function Biology Essay

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Carbohydrates consist of the elements carbon, hydrogen and oxygen with a ratio of hydrogen twice that of carbon and oxygen. Carbohydrates include sugars, starches, cellulose and many other compounds found in living organisms. In their basic form, carbohydrates are simple sugars or monosaccharides. These simple sugars can combine with each other to form more complex carbohydrates. The combination of two simple sugars is a disaccharide. Carbohydrates consisting of two to ten simple sugars are called oligosaccharides, and those with a larger number are called polysaccharides. Zamora, A. (2013). Carbohydrates - Chemical Structure. Available: Last accessed 10th Feb 2013.

Now the definition of carbohydrates has been discussed, it is time to talk about the role of a carbohydrate in the body. Carbohydrates provide energy to the body and these are taken from the monosaccharide glucose. 'Monosaccharides are the simplest carbohydrates and are classified according to whether they are aldehyde or ketone derivatives, as well as the number of atoms contained in the molecule. Single hexoses, glucose and galactose require no digestion and can be absorbed directly into the bloodstream. Hexoses contain six carbon atoms, and are found in foods, while pentoses, ribose and deoxyribose contain five carbon atoms and are produced during the metabolism of foodstuffs.' Author Unknown. (Year Unknown). Monosaccharides. Available: Last accessed 10th Feb 2013., M. (Year Unknown). Apologia Biology, Module 5, The Chemistry of Life, Part B. Available: Last accessed 10th Feb 2013.

Glucose can be made from Glycogen which is found in the liver and muscles; however it can also be found in small amounts in other organs and tissues around the body. Glucose molecules split into smaller molecules and these oxidise to form water which in turn provides a large amount of energy.

Carbohydrates are important as they provide fuel to the central nervous system and the muscle system which is extremely important due to the sheer number and mass of nerves and muscles in our bodies which is needed to operate.

Stargazey. (2010). Essential Carbohydrates. Available: Last accessed 10th Feb 2013.


"Proteins consist of amino acids which are characterized by the -CH(NH2)COOH substructure. Nitrogen and two hydrogen's comprise the amino group, -NH2, and the acid entity is the carboxyl group, -COOH. Amino acids link to each when the carboxyl group of one molecule reacts with the amino group of another molecule, creating a peptide bond -C(=O)NH- and releasing a molecule of water (H2O). Amino acids are the basic building blocks of enzymes, hormones, proteins, and body tissues. A peptide is a compound consisting of 2 or more amino acids. Oligopeptides have 10 or fewer amino acids. Polypeptides and proteins are chains of 10 or more amino acids, but peptides consisting of more than 50 amino acids are classified as proteins." Zamora, A. (2013). Proteins, Amino Acids, Peptides, and Polypeptides. Available: Last accessed 10th Feb 2013.


A lipid is a fat-soluble molecule. To put it another way, lipids are insoluble in water but soluble in at least one organic solvent. The other major classes of organic compounds (nucleic acids, proteins, and carbohydrates) are much more soluble in water than in an organic solvent. Lipids do not share a common molecule structure.

Helmenstine, A.M, Ph.D.. (Year Unknown). Lipids - Introduction to Lipids. Available: Last accessed 10th Feb 2013.

Lipids cannot be dissolved in water, they are said to be hydrophobic, however ether, acetone and other lipids can dissolve a lipid.


Fahy, E. (Year Unknown). Lipids. Available: Last accessed 10th Feb 2013.

Lipids can be broken down into groups, the three major groups are

Fats; which are made up from three fatty acids and glycerol. These are called triglycerides and they can either be liquid or solid when they are at room temperature. When they are in their liquid stage, they are called oils and those that are in their solid stage are called fats. These can be saturated or unsaturated depending on the lipids structure.

Phospholipids; are made up from two fatty acids and one glycerol unit with a polar molecule and phosphate group. The polar head section of the molecule is hydrophilic which mans that it is attracted to water while the tail is hydrophobic which means that it is repelled by water. The non-polar tails organise themselves so that they are all facing each other and the polar heads face the opposite direction to interact with the water. Phospholipids are important and a vital component of cell membranes. These enclose the cytoplasm and all the other contents of a cell.

Steroids and Waxes; steroids are made up from cholesterol, sex hormones such as; estrogens', progesterone, testosterone and also include cortisone. Waxes which many plants, fruits and even animal fur or feathers have to protect them from water penetration are made up from an ester of fatty acid and alcohol.

Nucleic Acids;

Nucleic acids allow organisms to transfer genetic information from one generation to the next. There are two types of nucleic acids: deoxyribonucleic acid, better known as DNA and ribonucleic acid, better known as RNA.

When a cell divides, its DNA is copied and passed from one cell generation to the next generation. DNA contains the "programmatic instructions" for cellular activities. When organisms produce offspring, these instructions, in the form of DNA, are passed down. RNA is involved in the synthesis of proteins. "Information" is typically passed from DNA to RNA to the resulting proteins. Bailey, R. (Year Unknown). Nucleic Acids - The Structure and Function of Nucleic Acids. Available: Last accessed 10th Feb 2013.