Chapter 5 - Enzymes Flashcards
what is a catalyst?
a substance that increases the rate of a chemical reaction without being used up or changed itself
what are enzymes?
biological catalysts that speed up the rate of metabolic reactions
what does it mean by catalase?
an enzyme that catalyses the breakdown of hydrogen peroxide to water and oxygen
what does it mean by amylase?
an enzyme that catalyses the breakdown of starch to maltose
what does it mean by protease?
an enzyme that catalyses the breakdown of protein to amino acid
what does it mean by carbohydrases?
enzymes that breakdown carbohydrates
what does it mean by lipases?
enzymes that break down lipids (fats and oils)
what does it mean by maltase?
an enzyme that catalyses the break down of maltose to glucose
what does it mean by sucrase?
an enzyme that breaks down sucrose
what is a substate?
the substance that an enzyme causes to react
what is an active site?
the part of an enzyme molecule to which the substrate temporarily binds
what is a product?
the new substance formed by a chemical reaction
what does it mean by optimum?
best; for example, the optimum temperature of an enzyme is the temperature at which its activity is greatest
what does it mean by enzyme-substrate complex?
the short-lived structure formed as the substrate binds temporarily to the active site of an enzyme
what does it mean if a catalyse is described as enzyme specificity?
its only able to act on one specific substrate
what does it mean by range?
the lowest to the highest value
what does it mean by butter solution?
a liquid that has a know pH and that keeps that pH steady all the time
describe the structure of enzymes
they are proteins that contain a highly specific active site that fits a specific substrate
why are enzymes necessary in biological systems?
they speed up reactions so that less energy is needed for the reaction to occur
describe enzyme action
a substrate that fits the specific active site of the enzyme binds to create an enzyme-substrate complex, a reaction occurs (catalysed by the enzyme) and then the products are released
what does the statement ‘enzymes are highly specific’ mean?
the active site of the enzyme must bind to a substrate that has a complementary shape and so only specific reactions can be catalysed
state four factors that affect the rate of an enzyme-controlled reaction
*temperature
*pH
*substrate concentration
*enzyme concentration
describe the effect of temperature on the rate of an enzyme-controlled reaction
*as the temperature increases, so does the rate of reaction
*once the temperature exceeds optimum, the enzyme denatures and the rate of reaction decreases
why does the rate of an enzyme-controlled reaction increase when the temperature increases?
*as the temperature increases the particles have more kinetic energy
*this increases the chance of collisions between molecules being successful and leading to a reaction
if temperature increases above optimum, how does this affect enzyme function?
the active site will be distorted as the enzyme denatures and so it will no longer fit the substrate
describe the effect of pH on the rate of an enzyme-controlled reaction
*the rate of an enzyme catalysed reaction is fastest at the optimum pH
*if the pH is too high or low, the enzyme will work less efficiently and the active site may be denatured at extremes of pH
how does a pH that is very different to the optimum affect the enzyme activity?
the change in pH will distort the enzyme’s active site (denaturing it) so that it can no longer fit the specific substrate
