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Essential ideas:
- Analyses of protein activity and concentration are key areas of biochemical research.
- DNA is the genetic material that expresses itself by controlling the synthesis of proteins by the cell.
- Biological pigments include a variety of chemical structures with diverse functions which absorb specific wavelengths of light.
- Most biochemical processes are stereospecific and involve only molecules with certain configuration of chiral carbon atoms.
B.7 Vmax and Km
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Applications and skills:
Determination of the maximum rate of reaction (Vmax) and the value of the Michaelis constant (Km) for an enzyme by graphical means, and explanation of its significance. |
B.7 Competitive and non-competitive inhibitors
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Understandings:
Inhibitors play an important role in regulating the activities of enzymes. Applications and skills: Comparison of competitive and non-competitive inhibition of enzymes with reference to protein structure, the active site and allosteric site. |
B.7 Buffer solutions
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B.7 Calculating the pH of a buffer solution
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Applications and skills:
Calculation of the pH of buffer solutions, such as those used in protein analysis and in reactions involving amino acids in solution. |
B.7 The Beer - Lambert law
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Understandings:
Protein assays commonly use UV-vis spectroscopy and a calibration curve based on known standards Applications and skills: Determination of the concentration of a protein in solution from a calibration curve using the Beer–Lambert law. |
B.7 Analysis of protein concentration (UV-vis)
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Understandings:
Protein assays commonly use UV-vis spectroscopy and a calibration curve based on known standards Applications and skills: Determination of the concentration of a protein in solution from a calibration curve using the Beer–Lambert law. |
B.8 Nucleic acids
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Understandings:
Nucleotides are the condensation products of a pentose sugar, phosphoric acid and a nitrogenous base—adenine (A), guanine (G), cytosine (C), thymine (T) or uracil (U). Polynucleotides form by condensation reactions. DNA is a double helix of two polynucleotide strands held together by hydrogen bonds. RNA is usually a single polynucleotide chain that contains uracil in place of thymine, and a sugar ribose in place of deoxyribose. |
B.8 Protein synthesis
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Understandings:
The sequence of bases in DNA determines the primary structure of proteins synthesized by the cell using a triplet code, known as the genetic code, which is universal. Applications and skills: Deduction of the nucleotide sequence in a complementary strand of DNA or a molecule of RNA from a given polynucleotide sequence. |
B.8 Stability of DNA
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Applications and skills:
Explanation of the stability of DNA in terms of the interactions between its hydrophilic and hydrophobic components. |
B.8 DNA packaging
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Applications and skills:
Explanation of the origin of the negative charge on DNA and its association with basic proteins (histones) in chromosomes. |
B.8 GM foods
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Understandings:
Genetically modified organisms have genetic material that has been altered by genetic engineering techniques, involving transferring DNA between species. Applications and skills: Discussion of the benefits and concerns of using genetically modified foods. |
B.9 Biological pigments
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Understandings:
Biological pigments are coloured compounds produced by metabolism. The colour of pigments is due to highly conjugated systems with delocalized electrons, which have intense absorption bands in the visible region. |
B.9 Carotenoids
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Understandings:
Carotenoids are lipid-soluble pigments, and are involved in harvesting light in photosynthesis. They are susceptible to oxidation, catalysed by light. Applications and skills: Outline of the factors that affect the stabilities of anthocyanins, carotenoids and chlorophyll in relation to their structures. |
B.9 Anthocyanins
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Understandings:
Anthocyanins are aromatic, water-soluble pigments widely distributed in plants. Their specific colour depends on metal ions and pH. Applications and skills: Outline of the factors that affect the stabilities of anthocyanins. Explanation of the ability of anthocyanins to act as indicators based on their sensitivity to pH. |
Not mentioned in the video but it is included in the utilization section of the syllabus:
Anthocyanins filter out ultra-violet (UV) light and protect surrounding tissues from ultra-violet light damage. Bright light stimulates anthocyanin production. Many young tissues are protected with anthocyanins until they have a full complement of pigments and can properly function.
Anthocyanins filter out ultra-violet (UV) light and protect surrounding tissues from ultra-violet light damage. Bright light stimulates anthocyanin production. Many young tissues are protected with anthocyanins until they have a full complement of pigments and can properly function.
B.9 Porphyrin compounds
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Understandings:
Porphyrin compounds, such as hemoglobin, myoglobin, chlorophyll and many cytochromes are chelates of metals with large nitrogen-containing macrocyclic ligands. Hemoglobin and myoglobin contain heme groups with the porphyrin group bound to an iron(II) ion. |
B.9 Cytochromes
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Understandings:
Cytochromes contain heme groups in which the iron ion interconverts between iron(II) and iron(III) during redox reactions. |
B.9 Oxygen saturation of hemoglobin
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Applications and skills:
Explanation of the sigmoidal shape of hemoglobin’s oxygen dissociation curve in terms of the cooperative binding of hemoglobin to oxygen. Discussion of the factors that influence oxygen saturation of hemoglobin, including temperature, pH and carbon dioxide. Description of the greater affinity of oxygen for foetal hemoglobin. |
B.9 Carbon monoxide and hemoglobin
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Applications and skills:
Explanation of the action of carbon monoxide as a competitive inhibitor of oxygen binding. |
B.9 Colour stability of heme
B.10 Stereochemistry in amino acids
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Understandings:
With one exception, amino acids are chiral, and only the L-configuration is found in proteins. |
B.10 Stereochemistry in lipids
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Understandings:
Naturally occurring unsaturated fat is mostly in the cis form, but food processing can convert it into the trans form. Applications and skills: Description of the hydrogenation and partial hydrogenation of unsaturated fats, including the production of trans-fats, and a discussion of the advantages and disadvantages of these processes. Relative melting points of saturated and cis-/trans-unsaturated fats should be covered. |
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Advantages and disadvantages of hydrogenation of fats and oils.
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B.10 Hydrogenation of oils
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Understandings:
Naturally occurring unsaturated fat is mostly in the cis form, but food processing can convert it into the trans form. Applications and skills: Description of the hydrogenation and partial hydrogenation of unsaturated fats, including the production of trans-fats, and a discussion of the advantages and disadvantages of these processes. |
B.10 Stereochemistry in carbohydrates
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Understandings:
D and L stereoisomers of sugars refer to the configuration of the chiral carbon atom furthest from the aldehyde or ketone group, and D forms occur most frequently in nature. Ring forms of sugars have isomers, known as α and β, depending on whether the position of the hydroxyl group at carbon 1 (glucose) or carbon 2 (fructose) lies below the plane of the ring (α) or above the plane of the ring (β). |
B.10 Starch, glycogen and cellulose
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Applications and skills:
Explanation of the structure and properties of cellulose, and comparison with starch. Discussion of the importance of cellulose as a structural material and in the diet. |
B.10 Dietary fibre
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Applications and skills:
Discussion of the importance of cellulose as a structural material and in the diet. |
B.10 Stereochemistry in vitamins
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Understandings:
Vision chemistry involves the light activated interconversion of cis- and trans- isomers of retinal. Applications and skills: Outline of the role of vitamin A in vision, including the roles of opsin, rhodopsin and cis- and trans-retinal. Guidance: Names of the enzymes involved in the visual cycle are not required. |
