enzymes

Question 1

what are enzymes?

Answer 1

enzymes are biological catalysts that speed up chemical reactions

Question 2

what is a catalyst?

Answer 2

a substance that speeds up a chemical reaction without being used up in the reaction itself

Question 3

give 2 examples of intracellular enzymes

Answer 3

hydrogen peroxide-toxic by product of several cellular reactions

catalase- catalyse the breakdown of hydrogen peroxide to harmless oxygen and water

Question 4

give 2 examples of extracellular enzymes

Answer 4

amylase- found in saliva, catalyses the hydrolysis of starch into maltose in the mouth

trypsin- catalyses the hydrolysis of peptide bonds, produced by pancreas and secreted into the small intestine

Question 5

what type of proteins are enzymes

Answer 5

globular proteins

Question 6

what are the 4 factors that affect enzyme activity?

Answer 6

temperature, PH, Enzyme conc and substrate conc

Question 7

the equation for temperature Coefficient

Answer 7

Q10=R2(rate at higher temperature)/ R1 (rate at a lower temperature)

Question 8

what does a temperature coefficient show?

Answer 8

shows how much the rate of a reaction changes when the temperature is raised by 10 degrees

Question 9

what are cofactors?

Answer 9

non protein substance

Question 10

what cofactor is used for the enzyme, amylase?

Answer 10

Chloride ions

Question 11

what are inorganic cofactors

Answer 11

they dont directly participate in the reaction so are not used up or changed in any way

Question 12

what are organic cofactors called?

Answer 12

coenzymes

Question 13

what are coenzymes?

Answer 13

they participate in the reaction and are changed by it, they act as carriers, moving chemical groups between different enzymes, they are continually recycled during this process

Question 14

what is a prosthetic group?

Answer 14

when a cofactor is tightly bound to the enzyme

Question 15

what is an example of a prosthetic group?

Answer 15

zinc ions are a prosthetic group for carbonic anhydrase, zinc ions are a permanent part of the enzymes active site

Question 16

what is competitive inhibition?

Answer 16

the inhibitor has a similar shape to the substrate so they compete with the substrate molecules to bind to the active site but no reaction takes place.

Question 17

what is non competitive inhibition?

Answer 17

inhibitors bind to the enzyme away from its active site, allosteric site. this causes the active site to change shape so the substrate molecules can no longer bind to it

Question 18

what bonds can make inhibition irreversible

Answer 18

strong covalent bonds between the enzyme and inhibitor

Question 19

what bonds can make inhibition reversible

Answer 19

weaker hydrogen or weak ionic bonds

Question 20

name 2 examples of medicinal drugs that are enzyme inhibitors

Answer 20

penicillin inhibits the enzyme transpeptidase which catalyses the formation of proteins in bacterial cell walls

some antiviral drugs

Question 21

name 2 examples of metabolic poisons that are enzyme inhibitors

Answer 21

cyanide- inhibitor of cytochrome c oxidase, an enzyme that catalyses respiration reactions

malonate inhibits succinate dehydrogenase which also catalyses respiration reactions

Question 22

why are some enzymes synthesized as inactive precursors?

Answer 22

to prevent them causing damage to cells.