Introduction to biochemistry
B.1 Introduction to biochemistry (1 hour)
Pause for thought
The section on International-Mindedness for this introductory sub-topic stresses “the differences in the availability of nutritious food, which have major and diverse impacts on human health”. In the past the word ‘malnutrition’ would most probably have conjured up thoughts of children dying of hunger in the poorer parts of the world. Sadly this still happens but by far the greatest problem associated with malnutrition is obesity. As the statistics below show, 65% of the world’s population live in countries where being overweight and obese kill more people than being underweight. Obese people have a shorter life expectancy and are at greater risk of developing diabetes and cardiovascular disease.
The evolution of man? (Image from EmDocs)
The facts below produced by the World Health Organisation make sober reading.
- Worldwide obesity has nearly doubled since 1980.
- In 2008, more than 1.4 billion adults, 20 and older, were overweight. Of these over 200 million men and nearly 300 million women were obese.
- 35% of adults aged 20 and over were overweight in 2008, and 11% were obese.
- 65% of the world’s population live in countries where overweight and obesity kills more people than underweight.
- Overweight and obesity are the fifth leading risk for global deaths. At least 2.8 million adults die each year as a result of being overweight or obese.
- 44% of the diabetes burden, 23% of the ischaemic heart disease burden and between 7% and 41% of certain cancer burdens are attributable to overweight and obesity.
- More than 40 million children under the age of five were overweight in 2011.
- Obesity is preventable.
The WHO has also produced a map of the world showing the percentage obesity for both adults and children for each country.
As you teach this option consider whether you have a duty to stress the importance of a healthy diet and make students aware of the dangers of obesity.
Nature of Science
Biochemical systems involve many different reactions all occurring simultaneously in the same location. As technology has advanced more data has been collected. This in turn has lead to the discovery of patterns in metabolic reactions.
Learning outcomesAfter studying this topic students should be able to: Understand
Apply their knowledge to:
| Clarification notesThe intermediates involved in aerobic respiration and photosynthesis are not required. International-mindednessMetabolic reactions in the human body are dependent on the supply of nutrients through a regular and balanced diet. There are significant differences in the availability of nutritious food in different parts of the world. These differences have a major and diverse impact on human health. |
Teaching tipsExplain that essentially biochemical reactions taking place in the body – metabolism- can be divided into two types. These depend upon whether energy is being taken in and stored in the bonds of the larger molecules being synthesized (anabolism) or whether larger molecules are being broken down to release the energy required for the body to do work (catabolism). This then leads neatly into the two main chemical reaction types of condensation and hydrolysis. You will need to decide whether to spend time now explaining the condensation and reactions of 2-amino acids and monosaccharides and the hydrolysis reactions of proteins and polysaccharides or leave the detail until you cover proteins in B.2 and carbohydrates in B. 4. It does make a lot of sense to cover them in this topic to emphasise the common nature of the reactions and also you can then revise/review them when you then come to them again in B.2 and B.4. Stress that when two different 2-amino acids condense there are actually at least two possible organic products (there may be more if one of the 2-amino acids has two –NH2 or two –COOH groups) as well as water. Photosynthesis and respiration only need to be dealt quite simply for this topic so there is no need to involve ATP etc., or look at the intermediate steps in the processes. Concentrate more on the main reactants and products and the importance of the energy conversions. | Study guide
Page 124 QuestionsFor ten 'quiz' questions (for quick testing of knowledge and understanding with the answers explained) see MC test: Introduction to biochemistry. For short-answer questions see Introduction to biochemistry questions together with the worked answers on a separate page Introduction to biochemistry answers. Vocabulary listmetabolic |
Teaching slides
Teachers may wish to share these slides with students for learning or for reviewing key concepts.
Introduction to biochemistry:
Introduction to biochemistry:
Introduction to biochemistry:
Introduction to biochemistry:
Introduction to biochemistry:
Introduction to biochemistry:
Introduction to biochemistry:
Other resources
1. A video that emphasises the difference between anabolic and catabolic processes by SnapshotBiology.
Anabolic & catabolic processes
2. A good description of photosynthesis.
3. Some examples of condensation reactions to form disaccharides.
Condensation of sugars to form disaccharides