2.5 : Enzymes

Question 1

what type of collisions occur in the absence of enzymes?

Answer 1

random collisions

Question 2

what effect do enzymes have on a reaction? why?

Answer 2

they increase the rate of reaction, as molecules will be attracted to these biological catalysts

Question 3

what binds to the active site?

Answer 3

a substrate molecule binds to an enzymes active site

Question 4

what is the active site?

Answer 4

region on an enzyme molecule where the substrate molecule binds

Question 5

when an enzyme-substrate complex formed, what state is it raised to?

Answer 5

raised to transitional state (short period) –> before substrate is formed into product or broken down into others by catalytic properties of the active site.
(product molecules are released with the unchanged enzyme)

Question 6

what is enzyme specificity?

Answer 6

the way in which enzymes are specific in the way that a substrate molecule binds to their active site, therefore conducts a specific action.

Question 7

how does an enzyme-substrate complex form?

Answer 7

at the active site, the arrangement of a few amino acid molecules in an enzyme matches the certain groupings on the substrate molecules –> bind –> enzyme-substrate complex formed;

Question 8

what occurs when an enzyme-substrate complex is formed? what is this called? why is this important?

Answer 8

during the formation of an enzyme-substrate complex –> a slight change of shape is induced in the enzyme = induced-fit hypothesis.
–> slight change in shape is important in raising the substrate molecule to the transitional state –> able to react & form enzyme-substrate complex (temporarily).

Question 9

what role do enzymes play in metabolism?

Answer 9

allow some reaction to take place –> many metabolic reaction only occur in presence of specific enzymes.

Question 10

what are extracellular enzymes?

Answer 10

enzymes that work externally

–> parcelled up & secreted out of cell

Question 11

what are intracellular enzymes?

Answer 11

enzymes that remain and function within a cell

-_> found inside organelles & inside membranes of organelles & in cytosol around organelles & plasma membrane.

Question 12

what effect on metabolic reactions do cells have by controlling the producing of certain enzymes at certain times?

Answer 12

cells are able to control what chemical reactions occur in the cytoplasm, based on the enzyme produced & present.

Question 13

what is denaturation? when does this occur?

Answer 13

• a structural change in a protein that alters its three-dimensional shape.
• occurs when bonds, formed between different amino acid residues, within the enzyme break and change the shape of the active site.

Question 14

how does temperature cause denaturation of an enzyme? is this reversible?

Answer 14

-when there is an increase in temperature –> atoms vibrate more violently as molecules have increased active energy –> disrupts bonds within the enzyme causing a change in its chemical characteristics
(proteins are denatured by heat)
-irreversible
(also increased reaction rate as molecules vibrate more
–> more likely to collide & react)

Question 15

what is a temperature coefficient?

Answer 15

a measure of the rate of change in a biological system as a consequence of increasing the temperature by a certain factor (10°).

Question 16

what is the effect of pH on enzyme shape and activity? is this reversible?

Answer 16

• structure of enzyme/protein changes when a change in pH alters the ionic charge on the acidic and basic groups in the peptide chain –> shape of active site is lost.
• change in pH from the enzymes optimum –> alters bonding patterns.
• reversible –> if the change in acidity/alkalinity is not too extreme (pH returns to optimum –> active site reforms)

Question 17

why are enzymes beneficial in industrial uses/processes?

Answer 17

• they are efficient : tiny quantity can catalyse a large amount of product.
• they are effective at normal temperatures and pressures : only require a limited input of energy (as heat & high pressure.
• are highly specific : able to catalyse changes in one particular compound / type of bond.

Question 18

why are some industrial enzymes obtained from microorganisms?

Answer 18

• able to be grown economically in fermenters throughout years (rather than a short growing system)
• grow quickly and produces a large quantity of enzymes relative to cell mass.
• may be modified genetically with comparative ease (production of insulin - human)
• may be bacteria from extreme environments : adapted to function under abnormal conditions of pH or temp (don’t have to worry about denaturation)

Question 19

what are examples of enzymes from microorganisms in industrial uses?

Answer 19

• production of lactose free milk : using lactose from bacteria –> converts milks sugar into glucose & galactose.
• photographic industry : uses protease to digest the gelatine of old films –> able to reclaim silver residues.
• medical treatment of thromboses : use proteases (trypsin) or similar enzymes.
• brewing industry : use protease from bacteria to prevent cloudiness of beer.

Question 20

what is enzyme immobilisation?

Answer 20

Attachment of enzymes to insoluble materials which provide support & prevented from being leached away (entrapped between inert fibres)

Question 21

what are the advantages of enzyme immobilisation?

Answer 21

• permits reuse of enzyme preparation (doesn’t get leached away)
• product is enzyme free (doesn’t have to undergo additional processes)
• enzyme may be more stable & long lasting (protected by inert matrix)

Question 22

what are the steps in the production of lactose free milk?

Answer 22

-produced by application of enzyme technology using lactose obtained from bacteria = obtained by passing skimmed milk through a column containing immobilised lactose.
PROCESS –> skimmed milk is input through a pasteurisation process (kills bacteria & prolongs shelf life) –> enters a column of immobilised lactose –> enters a quality control phase (examination of product for minimum level of quality) –> enters packaging plant