C1.1 Enzymes and metabolism Flashcards
C1.1.1—Enzymes as catalysts
Students should understand the benefit of increasing rates of reaction in cells.
C1.1.2—Role of enzymes in metabolism
Students should understand that metabolism is the complex network of interdependent and interacting
chemical reactions occurring in living organisms. Because of enzyme specificity, many different enzymes
are required by living organisms, and control over metabolism can be exerted through these enzymes.
C1.1.3—Anabolic and catabolic reactions
Examples of anabolism should include the formation of macromolecules from monomers by condensation
reactions including protein synthesis, glycogen formation and photosynthesis. Examples of catabolism
should include hydrolysis of macromolecules into monomers in digestion and oxidation of substrates in
respiration.
C1.1.4—Enzymes as globular proteins with an active site for catalysis
Include that the active site is composed of a few amino acids only, but interactions between amino acids
within the overall three-dimensional structure of the enzyme ensure that the active site has the necessary
properties for catalysis
C1.1.5—Interactions between substrate and active site to allow induced-fit binding
Students should recognize that both substrate and enzymes change shape when binding occurs.
C1.1.6—Role of molecular motion and substrate-active site collisions in enzyme catalysis
Movement is needed for a substrate molecule and an active site to come together. Sometimes large
substrate molecules are immobilized while sometimes enzymes can be immobilized by being embedded
in membranes.
C1.1.7—Relationships between the structure of the active site, enzyme–substrate specificity and
denaturation
Students should be able to explain these relationships.
C1.1.8—Effects of temperature, pH and substrate concentration on the rate of enzyme activity
The effects should be explained with reference to collision theory and denaturation.
Application of skills: Students should be able to interpret graphs showing the effects.
NOS: Students should be able to describe the relationship between variables as shown in graphs. They
should recognize that generalized sketches of relationships are examples of models in biology. Models in
the form of sketch graphs can be evaluated using results from enzyme experiments.
C1.1.9—Measurements in enzyme-catalysed reactions
Application of skills: Students should determine reaction rates through experimentation and using
secondary data.
C1.1.10—Effect of enzymes on activation energy
Application of skills: Students should appreciate that energy is required to break bonds within the
substrate and that there is an energy yield when bonds are made to form the products of an enzymecatalysed reaction. Students should be able to interpret graphs showing this effect
C1.1.11—Intracellular and extracellular enzyme-catalysed reactions
Include glycolysis and the Krebs cycle as intracellular examples and chemical digestion in the gut as an
extracellular example.
C1.1.12—Generation of heat energy by the reactions of metabolism
Include the idea that heat generation is inevitable because metabolic reactions are not 100% efficient in
energy transfer. Mammals, birds and some other animals depend on this heat production for maintenance
of constant body temperature.
C1.1.13—Cyclical and linear pathways in metabolism
Use glycolysis, the Krebs cycle and the Calvin cycle as examples.
C1.1.14—Allosteric sites and non-competitive inhibition
Students should appreciate that only specific substances can bind to an allosteric site. Binding causes
interactions within an enzyme that lead to conformational changes, which alter the active site enough to
prevent catalysis. Binding is reversible.
C1.1.15—Competitive inhibition as a consequence of an inhibitor binding reversibly to an active site
Use statins as an example of competitive inhibitors. Include the difference between competitive and noncompetitive inhibition in the interactions between substrate and inhibitor and therefore in the effect of
substrate concentration.
