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level: 1.8 Factors affecting enzyme action

Questions and Answers List

level questions: 1.8 Factors affecting enzyme action

QuestionAnswer
Measuring enzyme-catalysed reactions (Changes that most frequently measured)- The formation of the products - The disappearance of the substrate
Graph of the formation of products-
Graph of the disappearance of the substrate-
Explanation for the graphs- Lots of substrates at first but no products - Substrates bind to active sites, and are broken down into products - Substrate decreases - Product increases - Less substrates to bind to enzymes and products get in the way - Rate of formation of product and disappearance of substrate decreases - Both graphs plateau as the substrates have been used up
Factors that affect enzymes- Temperature - pH - Enzyme concentration - Substrate concentration - Presence of inhibitors
Denature meaning- When the active site has changed shape - Breaks hydrogen bonds holding tertiary structure together - Enzyme and substrate don't fit together - The enzyme no longer functions as a catalyst
Temperature affecting enzymes- Increase in temperature increases rates of reaction - Enzymes vibrate more + collide more with substrates (more kinetic energy) - Form more enzyme-substrate complexes - If temperature is too high, it breaks the bonds that hold the enzyme - Enzyme is denatured - Formation of enzyme substrate complexes decreases
pH affecting enzymes- All enzymes have an optimum pH value - Most human enzymes work at a pH of 7 - If pH is too low or too high the H+ and OH- ions found in acids and alkalis breaks the bonds holding the enzyme - Enzyme denatures
Enzyme concentration affecting enzymes- Increasing the enzyme concentration increases rates of reaction - More collision between substrates and enzymes - Excess enzymes has no further effect as there will be less substrates available
Substrate concentration affecting enzymes- Increasing substrate concentration increases rates of reaction - More collision between substrates and enzymes - Excess of substrate has no further effect as all active sites used up - This makes the initial rate of reaction the highest rate of reaction
Why calculate initial rate of reaction- It is when the reaction is fastest - Allows comparison
How do you use a tangent on a curve to calculate the rate- Draw straight line on curve (90 degrees) - Draw triangle from it - Divide the vertical line by the horizontal line
How to find the rate of reaction on a line graph- Draw a triangle from the line - Divide the vertical line by the horizontal line
How to calculate pH using calculator-Log10 (H+) e.g. -Log10 (5.4 x 10^-3)