C1.1 Enzymes and metabolism SL Flashcards
(18 cards)
Enzymes are catalysts which…
speed up the reaction but are itself unchanged by the reaction
Enzymes are __ proteins composed of __
globular proteins, one or more polypeptides
The 3D structure of enzymes is affected by changes in? (2)
temperature, pH
What is metabolism?
Set of life sustaining chemical transformations within the cells of living organisms
What is the role of enzymes in metabolism?
The reactions that allow organisms to grow and reproduce, maintain structures and respond to environments, are catalysed by enzymes
Subdivisions of metabolism (2)
Anabolism (build up) and Catabolism (break down)
Anabolism
Building up (protein synthesis, DNA synthesis, synthesis of complex carbohydrates) = ENDERGONIC PROCESS
Catabolism
Breaking down (digestion of food, cell respiration) = EXERGONIC PROCESS
Both types of metabolic reactions happen through…
a series of enzyme-mediated steps called METABOLIC PATHWAYS
The use of active site in enzymes
A substrate is locked into the active site –> reaction is catalysed –> products are released and the enzyme is reused
Induced-fit binding
The active site of an enzyme binds to a specific substrate, the shape of the active site and substrate fit in
Molecular motion in liquids and substrate-active site collisions
Molecules packed closely together but free to move -> contains both substrate and enzyme molecules, they will come together (rate can be increased with temperature) -> substrates are smaller and move faster
Denaturation of enzymes
Enzymes are proteins, pH and temperature can change their structure –> if shape of the active site is changed considerably, enzyme will not function
What is the benefit of catalysts
The increased rate of reaction enables processes to occur fast in ambient temperatures, e.g. respiration, digestion, growth
Example of anabolism
Photosynthesis: CO2 + water + other molecules –> macromolecules, synthesis of complex carbohydrates e.g. starch, cellulose, glycogen
Example of catabolism
digestion, in cell respiration glucose or lipids are oxidised into CO2 and water
Enzymes as globular proteins with an active site for catalysis
Active site contains only a few amino acids but interactions between all amino acids in the protein ensure that it has the necessary properties for catalysis
Effect of enzymes on activation energy
Same amount of energy is always used, but with enzymes the activation energy is lower = less energy needed to break bonds, faster rate of reaction
