enzymes - cofactors

Question 1

define cofactor

Answer 1

a substance that has to be present to ensure that an enzyme - catalysed reaction takes place at the appropriate rate

Question 2

define prosthetic groups

Answer 2

a non-protein component that forms a permanent part of a functioning protein molecule

Question 3

define temporary cofactors

Answer 3

these are substances that bind to the enzyme for a short time (temporarily) while the reaction is happening

Question 4

what are 2 examples of temporary cofactors

Answer 4

coenzymes and mineral Ion cofactors

Question 5

define coenzymes

Answer 5

small organic non-protein molecules that bind temporarily to the active site of enzyme molecules either before or at the same times that the substrate binds

Question 6

define mineral ion cofactors

Answer 6

a type of temporary cofactor that is an inorganic ion (doesn’t contain carbon)

Question 7

define enzyme substrate complex

Answer 7

complex formed by temporary binding of enzyme and substrate molecules during an enzyme-catalysed reaction

Question 8

what do some enzymes need and why ?

Answer 8

cofactors
- they only work if another small non-protein molecule is attached to them
–> especially those involved in catalysing oxidation-reduction reactions
- as some enzymes wouldn’t be able to do their job as efficiently

Question 9

what is the function of a prosthetic group ?

Answer 9

it is permanently bound by covalent bonds to an enzyme molecule

Question 10

what does the enzyme carbonic anhydrase contain and where ?

Answer 10

a zinc ion in the active site

Question 11

what is the function of carbonic anhydrase ?

Answer 11

• catalyses the interconversion of carbon dioxide and water to carbonic acid
  –> which then breaks down to protons and hydrogen-carbonate ions

Question 12

where is the enzyme found ?

Answer 12

• erythrocytes (RBC)

Question 13

what are most enzyme-catalysed reactions and depending on what ?

Answer 13

reversible reaction and depending on the concentration of the substrate or product molecules

Question 14

what is the balanced equation for the reaction including carbonic anhydrase ?

Answer 14

CO2 + H2 –> H2CO3 ??????

Question 15

why is the reaction including carbonic anhydrase important ?

Answer 15

as it enables carbon dioxide to be carried in the blood from respiring tissue to the lungs

Question 16

why is zinc important to humans ?

Answer 16

for polypeptide hormone , insulin , to function properly

Question 17

what does some enzymes work better in ?

Answer 17

in the presence of ions that are not permanently bound to them

Question 18

what happens during an enzyme-catalysed reaction and what does it form ?

Answer 18

• the enzyme + substrate molecules temporarily bind together to form –> enzyme substrate complex

Question 19

what does the presence of certain ions do ?

Answer 19

may temporarily bind to either the substrate

Question 20

what may the presence of certain ions do ?

Answer 20

the enzyme molecule may ease the formation of such E-S-c
–> increases the rate of the enzyme catalysed reaction

Question 21

what do some cofactors acts as ?

Answer 21

co-substrates as the substrate together form the correct shape to bind to the active site of the enzyme

Question 22

what do some cofactors change and why ?

Answer 22

• the charge distribution
  –>on the surface of the substrate molecule
  OR
  –>on the surface of the enzyme’s active site
  –> which makes the temporary bonds in the E-S-c easier to form

Question 23

what does amylase digest into and will only function if ?

Answer 23

starch into maltose and if chloride ions are present

Question 24

what are coenzymes not made of ?

Answer 24

protein and they are organic