B4 - Enzymes Flashcards
What are enzymes?
Biological catalysts that speed up chemical reactions but are not changed or used up in the process
- long chains of amino acids that fold up to have different shapes that allow specific binding of substrates
- they are protein molecules
Metabolic pathways
Sequences of enzymatically catalysed chemical reactions in a cell
- since every chemical reaction within a cell is controlled by an enzyme: a group of these reactions makes a metabolic pathway
Catabolic pathways
Complex molecules are broken down to simpler ones and energy is released
- e.g. digestion
Anabolic pathways
Build up large chemicals and compounds which requires energy
- e.g. making glycogen in your liver
Lock and Key Theory
Theory of enzyme catalysis stating that the active site’s structure is complementary to the structure of the substrate
Active site
A region on an enzyme that binds to a protein or other substance during a reaction
- complementary in shape to the substrate it binds to forming an enzyme-substrate complex
Substrate
A specific reactant acted upon by an enzyme
Factors affecting enzyme activity (4)
- Temperature
- pH
- Enzyme concentration
- Substrate concentration
Enzyme Concentration on Enzyme Activity
- Increasing the concentration of enzymes increases the rate of reaction
- Enzymes are more likely to collide with substrates and therefore more E-S complexes form
- If the concentration of substrate is limited then eventually there will be no further effect
Substrate Concentration on Enzyme Activity
- Increasing the concentration of substrate increases the rate of reaction (True up to a saturation point)
- Collisions are more likely so more E-S complexes form
- The concentration will decrease over time therefore the rate of reaction will also decrease
- therefore, the initial rate is the highest
What are optimum conditions?
Conditions in which the enzyme works best in
Optimum temperature for enzymes
37˚C body temp
What are reactions without enzymes like?
The reactions would need a lot more energy to take place
- chemical reactions need something to decrease their duration and increase their quality
Temperature on enzyme activity
- Increasing the temperature increases the rate of reaction
- The increase in kinetic energy means they can move faster and are more likely to collide and form E-S complexes
- Increasing the temperature above the optimum can break bonds which results in the active site changing
- The substrate no longer fits as the enzyme is denatured and doesn’t function as a catalyst
Complementary shape of an enzyme
The shape of the active site of an enzyme which is corresponding to the shape of the substrate
