Essential idea: Living organisms control their composition by a complex web of chemical reactions.
Above is just a small part of the IUBMB-Sigma-Nicholson Metabolic Pathways Chart aims to show all the metabolic pathways found in eukaryote cells. The chart in it's entirety shows how complex the chemicals reactions needed to support life in a single cell unit.
Understandings, applications and skills:
| 2.1.U1 | Molecular biology explains living processes in terms of the chemical substances involved. |
| 2.1.U2 | Carbon atoms can form four covalent bonds allowing a diversity of stable compounds to exist. |
| 2.1.U3 | Life is based on carbon compounds including carbohydrates, lipids, proteins and nucleic acids. [Sugars include monosaccharides and disaccharides. Only one saturated fat is expected and its specific name is not necessary. The variable radical of amino acids can be shown as R. The structure of individual R-groups does not need to be memorized.] |
| 2.1.U4 | Metabolism is the web of all the enzyme-catalysed reactions in a cell or organism. |
| 2.1.U5 | Anabolism is the synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers by condensation reactions. |
| 2.1.U6 | Catabolism is the breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers. |
| 2.1.A1 | Urea as an example of a compound that is produced by living organisms but can also be artificially synthesized. |
| 2.1.S1 | Drawing molecular diagrams of glucose, ribose, a saturated fatty acid and a generalized amino acid. [Only the ring forms of D-ribose, alpha–D-glucose and beta-D-glucose are expected in drawings.] |
| 2.1.S2 | Identification of biochemicals such as sugars, lipids or amino acids from molecular diagrams. [Students should be able to recognize from molecular diagrams that triglycerides, phospholipids and steroids are lipids. Drawings of steroids are not expected. Proteins or parts of polypeptides should be recognized from molecular diagrams showing amino acids linked by peptide bonds.] |
[Text in square brackets indicates guidance notes]
StarterCarbon is a tramp why is carbon such a great molecule for building compounds? This is a chemistry video, but useful for students also studying chemistry and great for those that want to go into greater depth.
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Presentation and notes
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 2.1 Molecules to metabolism 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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Chemical bonds
Chemical bond formation by Lifewire from W H Freeman Condensation and hydrolysis by Terry Brown Organic molecules Quiz on inorganic versus organic molecules by i-Biology Macromolecules Macromolecules by Lifewire from W H Freeman |
Anabolism and Catabolism
Overview of metabolism by University of Texas Overview of metabolism - anabolism and catabolism by the Khan Academy |
Nature of science:
Falsification of theories—the artificial synthesis of urea helped to falsify vitalism. (1.9)
Wöhler accidentally synthesised urea in 1828, whilst attempting to prepare ammonium cyanate. In a letter to a colleague he says “I can no longer, so to speak, hold my chemical water and must tell you that I can make urea without needing a kidney, whether of man or dog". This is supposed to undermine vitalism as organic chemicals were previously thought to be synthesised only by organisms.
Vitalism nowadays has no credit as a theory, but above statement is seen by many from a historical perspective to be untrue. For an outline on vitalism read this article by William Betchel. In essense vitalism proposes that an unknowable factor is essential in explaining life, not simply that only organisms can synthesise organic compounds. Vitalism on this premise is both unscientific and and unfalsifiable.
Q - If evidence arises that contradicts a theory should the evidence be questioned or the theory modified, possibly even rejected?
Wöhler accidentally synthesised urea in 1828, whilst attempting to prepare ammonium cyanate. In a letter to a colleague he says “I can no longer, so to speak, hold my chemical water and must tell you that I can make urea without needing a kidney, whether of man or dog". This is supposed to undermine vitalism as organic chemicals were previously thought to be synthesised only by organisms.
Vitalism nowadays has no credit as a theory, but above statement is seen by many from a historical perspective to be untrue. For an outline on vitalism read this article by William Betchel. In essense vitalism proposes that an unknowable factor is essential in explaining life, not simply that only organisms can synthesise organic compounds. Vitalism on this premise is both unscientific and and unfalsifiable.
Q - If evidence arises that contradicts a theory should the evidence be questioned or the theory modified, possibly even rejected?
