2.1 Molecules to Metabolism
Understandings:
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.
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.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.
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.
Organic Compounds = Carbon compounds
Countless chemical reactions take place in cells and are responsible for all the actions of organisms. Together, these reactions make up an organism's metabolism.
In all reactions:
Two types of metabolic reactions take place in the cell: 'building up' (anabolism) and 'breaking down' (catabolism).
In all reactions:
- chemical bonds in the reacting molecules are broken; this takes in energy
- new chemical bonds form to make the products; this gives out energy
Two types of metabolic reactions take place in the cell: 'building up' (anabolism) and 'breaking down' (catabolism).
Applications and skills:
2.1.A1 Urea as an example of a compound that is produced by living organisms but can also be artificially synthesized.
Urea CH4N2
Urea,(NH2)2CO, is a colorless organic chemical compound also known by the name carbamide, as established by the World Health Organization. It is highly soluble in water and is essentially the waste produced when the body metabolizes protein. It is not only produced by humans, but also by many other mammals, as well as amphibians and some fish. Urea was the first natural compound to be artificially synthesized using inorganic compounds — a scientific breakthrough.
2.1.S1 Drawing molecular diagrams of glucose, ribose, a saturated fatty acid and a generalized amino acid.
2.1.S2 Identification of biochemicals such as sugars, lipids or amino acids from molecular diagrams.
You can visualize molecules MolView or Jmol
Guidance:
2.1.A1 Urea as an example of a compound that is produced by living organisms but can also be artificially synthesized.
Urea CH4N2
Urea,(NH2)2CO, is a colorless organic chemical compound also known by the name carbamide, as established by the World Health Organization. It is highly soluble in water and is essentially the waste produced when the body metabolizes protein. It is not only produced by humans, but also by many other mammals, as well as amphibians and some fish. Urea was the first natural compound to be artificially synthesized using inorganic compounds — a scientific breakthrough.
2.1.S1 Drawing molecular diagrams of glucose, ribose, a saturated fatty acid and a generalized amino acid.
2.1.S2 Identification of biochemicals such as sugars, lipids or amino acids from molecular diagrams.
You can visualize molecules MolView or Jmol
Guidance:
- Only the ring forms of D-ribose, alpha–D-glucose and beta-D-glucose are expected in drawings.
- 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.
- 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.
2.2 Water
Natre of science:
2.2.NOS Use theories to explain natural phenomena—the theory that hydrogen bonds form between water molecules explains the properties of water.
Understandings:
2.2.U1 Water molecules are polar and hydrogen bonds form between them.
2.2.U2 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water
2.2.U3 Substances can be hydrophilic or hydrophobic.
Applications and skills:
2.2.A1 Comparison of the thermal properties of water with those of methane.
2.2.A2 Use of water as a coolant in sweat.
2.2.A3 Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water.
Guidance:
2.2.NOS Use theories to explain natural phenomena—the theory that hydrogen bonds form between water molecules explains the properties of water.
Understandings:
2.2.U1 Water molecules are polar and hydrogen bonds form between them.
2.2.U2 Hydrogen bonding and dipolarity explain the cohesive, adhesive, thermal and solvent properties of water
2.2.U3 Substances can be hydrophilic or hydrophobic.
Applications and skills:
2.2.A1 Comparison of the thermal properties of water with those of methane.
2.2.A2 Use of water as a coolant in sweat.
2.2.A3 Modes of transport of glucose, amino acids, cholesterol, fats, oxygen and sodium chloride in blood in relation to their solubility in water.
Guidance:
- Students should know at least one example of a benefit to living organisms of each property of water.
- Transparency of water and maximum density at 4°C do not need to be included.
- Comparison of the thermal properties of water and methane assists in the understanding of the significance of hydrogen bonding in water.
2.3 Carbohydrates & lipids
Essential idea: Compounds of carbon, hydrogen and oxygen are used to supply and store energy.
2.3.U1 Monosaccharide monomers are linked together by condensation reactions to form disaccharides and polysaccharide polymers.
2.3.U2 Fatty acids can be saturated, monounsaturated or polyunsaturated.
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.
Guidance:
2.3.U1 Monosaccharide monomers are linked together by condensation reactions to form disaccharides and polysaccharide polymers.
2.3.U2 Fatty acids can be saturated, monounsaturated or polyunsaturated.
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.
Guidance:
- The structure of starch should include amylose and amylopectin.
- Named examples of fatty acids are not required.
- Sucrose, lactose and maltose should be included as examples of disaccharides produced by combining monosaccharides.