enzymes

Question 1

what are enzymes

Answer 1

soluble globular proteins

biological catalysts

Question 2

anabolic reaction

Answer 2

building new products from substrates

Question 3

catabolic reaction

Answer 3

breaking down substrates to products

(catastrophic)

Question 4

how does extracellular action usually happen

Answer 4

by secretion

Question 5

describe the enzyme catalase

Answer 5

intracellular enzyme

has a quaternary structure
has 4 haem groups

breaks down hydrogen peroxide

Question 6

describe the enzyme amylase

Answer 6

extracellular enzyme
produced in salivary glands and pancreas

starch is partially broken down to maltose
then into glucose (by maltase)

Question 7

when we increase the enzyme concentration, what is the limiting factor

Answer 7

substrate concentration

used up while there’s a surplus of active sites
therefore an increase in enzyme concentration has no effect on rate

Question 8

how do we make a ‘linear increase’ when we add enzyme concentration

Answer 8

adding more substrate

Question 9

when we increase the subsrate concentration, what is the limiting factor

Answer 9

enzyme concentration

all active sites become occupied
(substrate saturation)
therefore an increase in substrate concentration has no effect on the rate

Question 10

how do we make a ‘linear increase’ when we add substrate concentration

Answer 10

add more enzymes

Question 11

when looking at a graph for the effect of temperature on enzyme activity, what is the peak?

Answer 11

maximum rate

shows maximum number of successful collisions
therefore maximum number of ESC

Question 12

what causes a rapid decrease after we increase the temperature past optimum

Answer 12

higher temperature causes breaking of bonds holding the protein’s shape

change in the tertiary structure

denaturation
(no longer complementary to the substrate active site so it can’t function)

Question 13

when does the temperature coefficient not apply

Answer 13

when the enzymes have denatured

Question 14

what is the difference in enzymes that are in organisms adapted to cold environments

Answer 14

enzymes have more flexible structures

making them less stable

therefore smaller temperature changes denature them

Question 15

what is the difference in enzymes that are in organisms adapted to hot environments

Answer 15

enzymes have more bonds (esp. hydrogen bonds and sulfur bridges) in their tertiary structure

making them very stable

which means they are more resistent to change as the temperature rises

Question 16

how does pH affect enzyme activity

Answer 16

hydrogen ions interact with polar and charged R-groups

changing the concentration of Hydrogen ions changes the degree of this interaction

Question 17

how does a lower pH affect enzyme structure

Answer 17

more hydrogen ions present

less R-groups able to interact with each other

leads to bond breaking and shape changing

Question 18

how does a higher pH affect enzyme structure

Answer 18

less hydrogen ions present

more R-groups able to interact with each other

leads to bond forming and shape changing

Question 19

how is the maximum rate of reaction noted

Answer 19

Vmax

Question 20

define the temperature coefficient

how is it calculated

Answer 20

ratio between rates at two different temperatures

rate at t+10degrees celsius / rate at t degrees celsius

Question 21

if a pH is changed slightly what can enzymes do if the pH is restored to the optimum

Answer 21

renaturation – protein resume its normal shape

Question 22

define metabolism

Answer 22

sum of all reactions and reaction pathways happening in a cell or organism

Question 23

describe the lock and key hypothesis

Answer 23

only a specific substrate with fit the active site of an enzyme

when they bind, an ESC is formed

the substrates then react to form products, forming an EPC

the profucts are then released

Question 24

how is the substrate held in the active site of an enzyme

Answer 24

R-groups in the active site of an enzyme interact with the substrate R-groups

forming temporary bonds

Question 25

describe the induced fit hypothesis

Answer 25

the active site of an enzyme changes shape slightly as the substrate enters

Question 26

define an intracellular enzyme

Answer 26

enzyme that works within cells

Question 27

define an extracellular enzyme

Answer 27

enzymes that work outside the cell that made them

Question 28

describe trypsin

Answer 28

protease
produced in pancreas and released into s.intestine

digests proteins into small peptides which break down into amino acids by other proteases