Enzymes - Intro and Models

Question 1

define enzymes

Answer 1

Biological catalysts, made of protein, with a specific active site. They speed up reactions whilst remaining unchanged.

Question 2

define active site

Answer 2

indented area on the surface of an enzyme molecule with a shape that is complementary to the shape of the substrate molecule

Question 3

define catalyst

Answer 3

chemical that speeds up the rate of reaction and remains unchanged and reusable as the end of the reaction

Question 4

define metabolism

Answer 4

the chemical reactions that take place inside living cells or organisms

Question 5

define product

Answer 5

molecule produced from substrate molecules, by an enzyme catalysed reaction

Question 6

define substrate

Answer 6

molecule that is altered by an enzyme-catalysed reaction

Question 7

define metabolites

Answer 7

reactants, intermediates and products in enzyme-controlled reactions

Question 8

what is the turnover number

Answer 8

the number of reactions that an enzyme molecule can catalyse per second

Question 9

what kind of protein are enzymes

Answer 9

globular

Question 10

what provides the active site

Answer 10

a specific tertiary structure

Question 11

what are enzymes affected by

Answer 11

temperature and pH

Question 12

what is the optimum

Answer 12

the temperature or pH at which the enzyme works fastest

Question 13

what is denaturation

Answer 13

when enzymes lose their specific tertiary structure and shape and are unable to catalyse reactions

Question 14

why are enzymes specific

Answer 14

they are only able to catalyse one reaction with a particular substrate

Question 15

how do enzymes speed up reactions

Answer 15

by lowering the activation energy

Question 16

what are the two types of enzymes

Answer 16

extracellular and intracellular

Question 17

what are intracellular enzymes

Answer 17

enzymes that work inside cells

Question 18

give four examples of intracellular enzymes

Answer 18

• catalase
• ATP synthase
• DNA polymerase
• carbonic anhydrase

Question 19

what is the function of catalase

Answer 19

breaks down hydrogen peroxide into water and oxygen

Question 20

what is the function of ATP synthase

Answer 20

converts ADP to ATP and inorganic phosphate

Question 21

what is the function of DNA polymerase

Answer 21

catalyses the synthesis of DNA molecules from free nucleotides

Question 21

what is the function of carbonic anhydrase and where is it found

Answer 21

found in red blood cells
converts carbon dioxide to carbonic acid, which dissociates to produce H+ ions

Question 22

what are extracellular enzymes

Answer 22

enzymes that work outside cells

Question 23

give three examples of extracellular enzymes

Answer 23

• amylase
• trypsin
• lipase

Question 24

what is the function of amylase and where is it made

Answer 24

made in salivary glands (acts in mouth) and pancreas (acts in small intestine). breaks down starch into maltose

Question 25

what is the function of trypsin and where is it made

Answer 25

made in pancreas (acts in small intestine). digests proteins into smaller peptides by hydrolysing the peptide bonds

Question 26

what is the function of lipase

Answer 26

breaks down fats in food so they can be absorbed in the intestines

Question 27

how do enzymes work

Answer 27

by randomly colliding with substrate molecules. the substrates are held in a way that encourages the product to be formed.

Question 28

what are the two types of enzyme reactions

Answer 28

- catabolic - anabolic

Question 29

what are catabolic reactions

Answer 29

substrates are broken down

Question 30

what are anabolic reactions

Answer 30

substrates are joined to make a larger product

Question 31

what makes enzymes specific

Answer 31

the shape of the active site is complementary to the shape of the substrate

Question 32

how do enzymes lower the activation energy

Answer 32

by providing an active site where reactions can occur more easily than elsewhere

Question 33

what are the two models of enzyme action

Answer 33

- lock and key - induced fit

Question 34

which model is more widely accepted

Answer 34

induced fit

Question 35

describe the lock and key model

Answer 35

the complementary shape of the active site and the substrate molecule are like a lock and key

Question 36

describe the induced fit model

Answer 36

- the enzyme's active site changes slightly upon collision, making the active site fit closer to the substrate. - there may also be changes to the amino acids in the active site that contribute to holding the substrate in place