Essential idea: Compounds of carbon, hydrogen and oxygen are used to supply and store energy.
When you are building and drawing molecules it is essential to remember that it's the bonds between the atoms where energy is stored. Organic molecules are often complex and hence contain many bonds. The above molecular model shows a part of a cellulose molecule.
Understandings, applications and skills:
| 2.3.U1 | Monosaccharide monomers are linked together by condensation reactions to form disaccharides and polysaccharide polymers. [Sucrose, lactose and maltose should be included as examples of disaccharides produced by combining monosaccharides. The structure of starch should include amylose and amylopectin.] |
| 2.3.U2 | Fatty acids can be saturated, monounsaturated or polyunsaturated. [Named examples of fatty acids are not required.] |
| 2.3.U3 | Unsaturated fatty acids can be cis or trans isomers. |
| 2.3.U4 | Triglycerides are formed by condensation from three fatty acids and one glycerol. |
| 2.3.A1 | Structure and function of cellulose and starch in plants and glycogen in humans. |
| 2.3.A2 | Scientific evidence for health risks of trans fats and saturated fatty acids. |
| 2.3.A3 | Lipids are more suitable for long-term energy storage in humans than carbohydrates. |
| 2.3.A4 | Evaluation of evidence and the methods used to obtain the evidence for health claims made about lipids. |
| 2.3.S1 | Use of molecular visualization software to compare cellulose, starch and glycogen. |
| 2.3.S2 | Determination of body mass index by calculation or use of a nomogram. |
Starter
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"Biological molecules: you are what you eat" is a fast paced introduction from Crash Course's Hank Green
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Presentation and notes
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The presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.
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Below are the notes for this topic. Alternatively the 2.3 Carbohydrates and lipids bottom line template can be used as a note construction template in itself or as a checklist if you are using your own or another template such as the Cornell style template.
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Weblinks
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Condensation and hydrolysis
Condensation reactions by CEngage Animated Glycosidic bond formation by Mr T Animated triglyceride formation by Mr T Carbohydrates Explanation and animation from National Louis University Biomolecules - the carbohydrates by Wisc-Online Condensation of carbohydrates by Jones and Bartlett What happens when glucose is placed in water? by John Gianni Lipids The Molecular structure of fats by HHMI Lipids (and condensation animation) by National Louis University Biomolecules - the lipids by Wisc-Online |
Molecular visualisation software
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Nature of science:
Evaluating claims—health claims made about lipids in diets need to be assessed. (5.2) [covered by 2.3.A4]
International-mindedness:
Variation in the prevalence of different health problems around the world could be discussed including obesity, dietary energy deficiency, kwashiorkor, anorexia nervosa and coronary heart disease.
Theory of knowledge:
There are conflicting views as to the harms and benefits of fats in diets. How do we decide between competing views?
For Scientists the most important tool and the basis upon which conclusions are based is evidence based evaluation. See the presentation for key points to consider when evaluating evidence. These key points are generic and could be used with most evaluations, e.g. in your in investigation reports.
For Scientists the most important tool and the basis upon which conclusions are based is evidence based evaluation. See the presentation for key points to consider when evaluating evidence. These key points are generic and could be used with most evaluations, e.g. in your in investigation reports.
