Chapter 5 - Enzymes

Question 1

what is a catalyst?

Answer 1

a substance that increases the rate of a chemical reaction without being used up or changed itself

Question 2

what are enzymes?

Answer 2

biological catalysts that speed up the rate of metabolic reactions

Question 3

what does it mean by catalase?

Answer 3

an enzyme that catalyses the breakdown of hydrogen peroxide to water and oxygen

Question 4

what does it mean by amylase?

Answer 4

an enzyme that catalyses the breakdown of starch to maltose

Question 5

what does it mean by protease?

Answer 5

an enzyme that catalyses the breakdown of protein to amino acid

Question 6

what does it mean by carbohydrases?

Answer 6

enzymes that breakdown carbohydrates

Question 7

what does it mean by lipases?

Answer 7

enzymes that break down lipids (fats and oils)

Question 8

what does it mean by maltase?

Answer 8

an enzyme that catalyses the break down of maltose to glucose

Question 9

what does it mean by sucrase?

Answer 9

an enzyme that breaks down sucrose

Question 10

what is a substate?

Answer 10

the substance that an enzyme causes to react

Question 11

what is an active site?

Answer 11

the part of an enzyme molecule to which the substrate temporarily binds

Question 12

what is a product?

Answer 12

the new substance formed by a chemical reaction

Question 13

what does it mean by optimum?

Answer 13

best; for example, the optimum temperature of an enzyme is the temperature at which its activity is greatest

Question 14

what does it mean by enzyme-substrate complex?

Answer 14

the short-lived structure formed as the substrate binds temporarily to the active site of an enzyme

Question 15

what does it mean if a catalyse is described as enzyme specificity?

Answer 15

its only able to act on one specific substrate

Question 16

what does it mean by range?

Answer 16

the lowest to the highest value

Question 17

what does it mean by butter solution?

Answer 17

a liquid that has a know pH and that keeps that pH steady all the time

Question 18

describe the structure of enzymes

Answer 18

they are proteins that contain a highly specific active site that fits a specific substrate

Question 19

why are enzymes necessary in biological systems?

Answer 19

they speed up reactions so that less energy is needed for the reaction to occur

Question 20

describe enzyme action

Answer 20

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

Question 21

what does the statement ‘enzymes are highly specific’ mean?

Answer 21

the active site of the enzyme must bind to a substrate that has a complementary shape and so only specific reactions can be catalysed

Question 22

state four factors that affect the rate of an enzyme-controlled reaction

Answer 22

*temperature
*pH
*substrate concentration
*enzyme concentration

Question 23

describe the effect of temperature on the rate of an enzyme-controlled reaction

Answer 23

*as the temperature increases, so does the rate of reaction
*once the temperature exceeds optimum, the enzyme denatures and the rate of reaction decreases

Question 24

why does the rate of an enzyme-controlled reaction increase when the temperature increases?

Answer 24

*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

Question 25

if temperature increases above optimum, how does this affect enzyme function?

Answer 25

the active site will be distorted as the enzyme denatures and so it will no longer fit the substrate

Question 26

describe the effect of pH on the rate of an enzyme-controlled reaction

Answer 26

*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

Question 27

how does a pH that is very different to the optimum affect the enzyme activity?

Answer 27

the change in pH will distort the enzyme’s active site (denaturing it) so that it can no longer fit the specific substrate