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Time: 8 hours
Level: Introductory
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 Introduction Resource- This unit studies 'proteins'. Starting with a simple analysis of their molecular make up, the unit moves on to look at the importance of proteins and how they are digested and absorbed.
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- 1 Proteins Resource
- To understand the composition, digestion, function in the body, etc., of a protein you will need to have some knowledge of chemistry.
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- 2 Atoms and molecules Resource
- Everything around us, and in us, is made up of atoms, which you can consider as minute spheres. They are very, very small. A page of a book is about one million (1 000 000) atoms thick. There are about...
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- 3 Chemical compounds Resource
- Many molecules consist of atoms of more than one type of element, and they are called compounds. Carbon dioxide, methane and water from the list of gases above are all chemical compounds. Water is the...
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| | 4 The importance of protein
- 4 The importance of protein Resource
- From general knowledge about foods, what would you say are the main sources of protein in the average person's diet in the UK?
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| | 5 The chemistry of amino acids
- 5 The chemistry of amino acids Resource
- Human proteins are composed of 20 different amino acids (Table 3).
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- 6.1 Linking two amino acids Resource
- As we have seen earlier, atoms can combine to form molecules and now we will see how molecules can combine together to make bigger molecules. If two glycine molecules are placed side by side, as in Figure...
- 6.2 Linking more amino acids Resource
- Consider what would be possible if you placed another glycine molecule to the right of the dipeptide shown in Figure 4b. Another peptide bond could be formed between them to give a chain of three glycine...
- 6.3 Amino acid sequences Resource
- With 20 different amino acids as constituents and proteins several hundred amino acids long, it would in theory be possible to construct an almost infinite number of different protein molecules. But a...
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| | 7 Protein shapes and functions
- Introduction to shapes and functions Resource
- Although a protein may be composed simply of a single long chain of amino acids, it does not remain as an elongated string, but folds up into a very precise shape. The shape may be regular, like a helix...
- 7.1 Determining the shape Resource
- During your studies you will meet a number of words which have Latin or Greek roots and whose meaning you may be able to work out. Coming up very soon are the words ‘hydrophobic’ and ‘hydrophilic’. You...
- 7.2 A faulty shape Resource
- An example of the effect of a single change in the amino acid sequence of a protein is provided by haemoglobin, the protein in the red blood cells that binds oxygen as it is transported from the lungs...
- 7.3 Cooking eggs Resource
- Many solids melt as they get hotter, but eggs do not. They start as quite liquid in the fresh state and when they are heated, they go solid. This behaviour is a result of the effect of the heat on the...
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| | 8 Protein digestion and absorption
- 8.1 Protein balance Resource
- The blood vessels that pass close to the digestive system and collect the amino acids absorbed from the small intestine, travel first to the liver. The liver appears to monitor the amounts of the different...
- 8.2 Too much protein Resource
- There is no way of storing large quantities of amino acids in the human body and so if more are present in the blood than are needed, the surplus ones have to be broken down and removed from the body....
- 8.3 Too little protein Resource
- If insufficient protein is present in the diet for the body's needs, then it starts to break down its own proteins. Since muscles contain large amounts of protein, the result of a low-protein diet is muscle-wasting....
- 8.4 Nitrogen balance Resource
- In a healthy person, there should be a balance between the input of nitrogen to the body and its output. The input is mostly from protein, though some other foods may contain small quantities of nitrogen...
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- 9 Summary Resource
- The human body, and everything else, is made up of atoms.
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| | References and Acknowledgements | |
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