2.4 enzymes

Question 1

3 ways to speed up a chemical reaction in a lab?

Answer 1

1. heat
2. catalyst
3. increasing pressure

Question 2

what are enzymes?

Answer 2

biological catalysts that speed up metabolic reactions in living organisms

Question 3

what happens to catalysts at the end of reactions?

Answer 3

they remain unchanged and can be used again

Question 4

what is the turnover number of an ezyme?

Answer 4

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

Question 5

wht type of proteins are enzymes?

Answer 5

globular proteins

Question 6

are enzymes soluble in water?

Answer 6

yes

Question 7

why are enzymes soluble in water?

Answer 7

because they are flobular proteins that are hydrophilic due to side groups in their amino acids

Question 8

what do anabolic do?

Answer 8

bild up/synthesise large polymers
endothermic
cellulose

Question 9

what do catabolic do?

Answer 9

break down large organic molecules
exothermic
digestion

Question 10

where do enzymes function?

Answer 10

both intracellularly and extracellularly

Question 11

what type of process is DNA replication?

Answer 11

intracellular

Question 12

an example of an intracellular enzyme that works in the membrane?

Answer 12

respiration which happens in the inner membrane of mitochondria when ATPase synthesises ATP

Question 13

where is amylase produced?

Answer 13

pancreas + salivary glands

Question 14

where is trypsin produced?

Answer 14

in the pancreas

Question 15

list 4 extracellular enzymes

Answer 15

protease
carbohydrase
lipase
cellulase

Question 16

which intracellular enzyme has the largest turnover number?

Answer 16

catalase
6 million per second

Question 17

what do white blood cells use cataase for?

Answer 17

kill microbes once ingested

Question 18

what is a metabolic pathway?

Answer 18

a metabolic pathway is a series of consecutive reactions with each step being catalysed by a different enzyme. specific for the substrate produced

Question 19

what happens in a maetabolic pathway when one enzyme can’t function?

Answer 19

the metabolic pathway can’t run

Question 20

in a metabolic pathway, what are reactants, intermediaries and products known as?

Answer 20

metabolites

Question 21

what are metabolites?

Answer 21

metabolites are the reactants, intermediaries and products

Question 22

two examples of complex metabolic pathways?

Answer 22

photosynthesis and respiration

Question 23

what are oxidoreductses?

Answer 23

enzymes that catalyses the transfer of electrons during oxidation and reduction

Question 24

what are transferases?

Answer 24

the transfer of a functional group from one to another

Question 25

what are do hydrolases do?

Answer 25

catalyse the hydrolysis bonds by the addition of water

Question 26

what do lyases do?

Answer 26

the splitting of bonds from oxidation and hyrolysis

Question 27

what do isomerases do?

Answer 27

the rearranging of a molecule

Question 28

what do ligases do?

Answer 28

joining of two molecules by formation of covalent bonds

Question 29

are enzymes specific?

Answer 29

yes, highly specific

Question 30

why are enzymes highly specific?

Answer 30

because they can only catalyse a particular bio mechanical reaction

Question 31

what's the general equation for an enzyme-controlled reaction?

Answer 31

ezyme + substrate enzyme substrate complex enzyme product complex enzyme + product

Question 32

what is the name of the energy needed for a reaction to start?

Answer 32

activation energy

Question 33

what is activation energy?

Answer 33

the energy required for a chemical reaction to start

Question 34

how do enzymes increase the rate of a reaction?

Answer 34

by creating a transition state between the enzyme and substrate that is more stable

Question 35

why does formation of the enzyme-substrate complex lower the activation energy?

Answer 35

holds them close together so they can bond more easily. puts a strain on substrate allowing the molecule to break down more easily.

Question 36

what maintains the precise shape of the acive site?

Answer 36

the remainder of the amino acids that make up the enzyme

Question 37

how could a mutation affect an enzyme?

Answer 37

sequence of amino acids will be altered and enzyme shape - tertiary xtructure - which may change it and prevent it from function

Question 38

"the active site on an enzyme is usually a .... or an indentation on the ....... of the molecule"

Answer 38

the active site on an enzyme is usually a CLEFT or an indentation on the SURFACE of the molecule

Question 39

how many amino acids usually make up the active site?

Answer 39

6 to 10 amino acids

Question 40

what will change the shape of an active site?

Answer 40

temperature pH

Question 41

why does change in temperature and pH affect the enzymes ability to function?

Answer 41

because the bonds that hold proteins in their tertiary struture are effected

Question 42

which part of an enzyme participates in the biomechanical reactions?

Answer 42

the active site. even though theyre large globular proteins

Question 43

what happens if the molecules do not have complementary shape?

Answer 43

the active site will not fit and will not bind

Question 44

what does the lock and key hypothesis state?

Answer 44

that the substrate molecule and enzyme will fit exactly like a key in a lock.

Question 45

what did US biochemist Daniel Koshland propose?

Answer 45

he proposed a modification of the lock and theory in 1958 that the active site is not initially an induced fit

Question 46

how does the more recently proposed model of the lock and key theory work?

Answer 46

as the substrate moves into the active site, forces between the 2 molecules distort the enzyme and active site so it is tight

Question 47

why is the formation of the enzyme-substrate complex good?

Answer 47

it allows the lowering of activation energy required to form products

Question 48

what factors affect enzymes?

Answer 48

temperature pH concentration of enzymes concentration of substrate

Question 49

at the beginning of the reaction, why is the initial rate of reaction fastest?

Answer 49

at the beginning of the reaction, the enzyme and substrate complex have a greater chance of succesfully colliding

Question 50

why does the rate of reaction slow down as the reaction proceeds?

Answer 50

because substrate is used up so the frequency of collisions decreases

Question 51

where is the maximum rate of reaction?

Answer 51

the initial rate of reaction under the right conditions

Question 52

how do you workout the coefficient Q10?

Answer 52

rate of reaction st (T-10)^0C / rate of reaction at T

Question 53

What happens when the enzyme gets too hot?

Answer 53

The enzyme vibrates The hydrogen and ionic bonds that hold the tertiary structure may break This causes denaturing

Question 54

Why are thermophilic bacteria’s enzymes more suited to hot temperatures?

Answer 54

Their enzymes have more disulfide bonds that don’t break in the heat

Question 55

What happens to rate of reaction as the substrate concentration increases?

Answer 55

-rate increases - this is because ES complex -more EP complex molecules are formed -more product

Question 56

Is the rate of reaction and substrate concentration proportional?

Answer 56

Yes they are directly proportional

Question 57

What will happen to the rate of reaction as the enzyme concentration increases?

Answer 57

The rate increases More active sites become more available More ES complexes form More EP form More product molecules formed

Question 58

Why does the rate of reaction stop at its Vmax?

Answer 58

Because all the active sites are occupied with substrate particles

Question 59

What are inhibitors?

Answer 59

Molecules that prevent enzymes from carrying out their normal function or slow them down

Question 60

What are the two types of inhibitors?

Answer 60

Competitive and non competitive

Question 61

Which inhibitor attaches to the active site?

Answer 61

Competitive They compete with the substrate for the active site on the enzyme

Question 62

What shape are the competitive inhibitors?

Answer 62

Similar to the substrate

Question 63

What is formed when the competitive inhibitors bind to the active site?

Answer 63

An enzyme-inhibitor complex is formed

Question 64

What do competitive inhibitors bond the enzyme with?

Answer 64

Relatively weak hydrogen bonds

Question 65

Which part of the enzyme do competitive inhibitors bind to?

Answer 65

Allosteric site

Question 66

How do competitive inhibitors work?

Answer 66

They bind to the allosteric site of the enzyme and cause a change in conformation of the active site so that the substrate can’t bind

Question 67

Can inhibitors be reversible?

Answer 67

Yes both reversible and irreversible

Question 68

What does the reversibility of an enzyme inhibitor depend on?

Answer 68

The strength of the bonds formed

Question 69

Which bonds are relatively weak for enzyme inhibitors?

Answer 69

Ionic and hydrogen bonds

Question 70

Which bonds make enzyme inhibitors unable to reverse?

Answer 70

Strong covalent bonds

Question 71

What does the end product in a metabolic pathway often do?

Answer 71

Act as a regulator of the pathway