Week 5- Enzymes

Question 1

catabolic pathways?

Answer 1

breaking down (glucose broken down for energy)
requires energy

Question 2

anabolic pathways?

Answer 2

synthetic pathways (synthesis of glucose from amino acids)
requires energy

Question 3

what is exergonic?

Answer 3

reactions release free energy
reactants are like a ball rolling down a hill
catabolism, generates disorder
delta G <0, spontaneous reaction

Question 4

what is endergonic?

Answer 4

reactions consume free energy
reactants are like a ball going up a hill
anabolism, order increases
delta G >0, non-spontaneous reaction

Question 5

how is activation energy reduced?

Answer 5

enzymes (catalyst)

final equilibrium and delta G don’t change

Question 6

what are the 3 basic steps of enzyme catalysts?

Answer 6

1- binding of substrate
2- conversion of bound substrate to bound product
3- release of product

done in the active site of the enzyme

Question 7

how do enzymes work?

Answer 7

• they have a specific active site that binds the substrate
• can change the shape of the substrate to facilitate product formation
• bind cofactors (coenzymes that also facilitate substrate change) can be metal ions or organic molecules
• stretch bonds in substrate molecules, making them unstable and more reactive to the action of other substrates

Question 8

what is acid-base catalysis?

Answer 8

enzyme side chains transfer H+ to or from the substrate causing a covalent bond break

Question 9

what is covalent catalysis?

Answer 9

a functional group in a side chain bonds covalently with the substrate

Question 10

what is metal ion catalysis?

Answer 10

metals on side chains loose or gain electrons

Question 11

first law of thermodynamics?

Answer 11

in energy conversion the total energy remains constant (enthalpy)
no energy is created or lost in conversion

Question 12

second law of thermodynamics?

Answer 12

universe tends towards disorder (entropy)

Question 13

which way is the reaction going to shift with a negative delta G?

Answer 13

right (forward)

Question 14

which way is the reaction going to shift with a positive delta G?

Answer 14

left (reverse)

Question 15

what does delta G do?

Answer 15

• mechanical work (muscles)
• transport work (carrier proteins)
• biochemical work (makes molecules)
• thermogenesis (ATP oxidation, heat)
• energy from fuel oxidation (NADH, FADH)

Question 16

Apoenzymes?

Answer 16

lacking cofactors

Question 17

Haloenzymes?

Answer 17

have cofactors

Question 18

what functional group does NAD accept?

Answer 18

hydride ions from lactate

Question 19

what functional group does FAD accept?

Answer 19

2 electrons as 2 hydrogen atoms

Question 20

oxireductases?

Answer 20

catalyze oxidation and reduction reactions

dehydrogenases: transfer hydrogen between a substrate and a coenzyme (NAD, FAD etc)

Question 21

transferases?

kinases?

Answer 21

transfer a specific functional group from the donor molecule to the acceptor molecule

transfer phosphate from ATP to a second substrate

Question 22

hydrolases?

Answer 22

hydrolysis reaction where bonds (CO, CS, CN) are cleaved by the addition of water
eg, digestive enzymes and lysosomal enzymes

Question 23

lyases?

carboxylases?

Answer 23

cleaving bonds in another way other than hydrolysis or ox- reduction
eg, aldolase, thiolases

carbon lyases that remove or add carboxyl group from organic compounds

Question 24

isomerases?

Answer 24

can convert a molecule from one isomer to another

eg, mutase catalyzes the shifting of a functional group from one position to another within the same molecule

Question 25

ligase? (synthetases)

Answer 25

``` synthesize bonds (CO, CS, CN, CC) in reactions couple to the cleavage of a high energy phosphate bond in ATP eg, DNA ligase ```

Question 26

units for Vmax? | km?

Answer 26

umol/min/mg | mM

Question 27

when do enzymes have high affinity for their substrate?

Answer 27

at low substrate concentrations

Question 28

does glucosekinase have a high or low affinity for a substrate?

Answer 28

low affinity for glucose so it requires a higher glucose concentration to function

Question 29

reversible inhibition? | competitive inhibition?

Answer 29

- inhibitor binds non-covalently to the active site and prevents substrate from binding - competitive inhibition, if substrate concentration is increased than the substrate will bind to the active site - this increases the Km but no effect on Vmax

Question 30

uncompetitive inhibitor?

Answer 30

- allosterically binds to the enzyme substrate complex and prevents the complex from releasing substrate - it cannot be surmounted - increasing the inhibitor will lower Vmax

Question 31

non-competive inhibitor?

Answer 31

- binds to the enzyme allosterically, changes shape and alters the active site - decreases the amount of active enzyme and reduces Vmax

Question 32

irreversible inhibitor?

Answer 32

inhibitor binds covalently to the active site and permanently inactivates the enzyme

Question 33

allosteric regulation?

Answer 33

effector molecule that binds to a regulatory subunit inducing the enzyme to change its shape - can inhibit or activate the enzyme

Question 34

allosteric enzymes?

Answer 34

- have multiple active site | - sensitive to low concentrations of inhibitors, important in regulating the entire metabolic pathway

Question 35

non- allosteric enzymes?

Answer 35

- have one active site | - small changes in activator concentration can promote large changes in the reaction

Question 36

what are isozymes?

Answer 36

- different form of the same enzyme - catalyze the same reaction but have different properties (temperature) - organisms can use to adjust temperature changes

Question 37

what happens to enzymes at high temperature?

Answer 37

non-covalent bonds break, loose its tertiary structure and is denatured

Question 38

what enzymes measure liver damage? | and for cardiac damage?

Answer 38

aspartate and alanine aminotransferases | creatinine kinase

Question 39

Beers Law?

Answer 39

the amount of light absorbed by a compound in a solution is directly related to the concentration of the compound in solution

Question 40

activation transfer coenzymes?

Answer 40

participate in catalysis by binding with a substrate

Question 41

oxidation reduction coenzymes?

Answer 41

do not form covalent bonds with the substrate

Question 42

cystic fibrosis?

Answer 42

Cl- secretion and secretion of water and other ions is impaired this alters the pH and dehydrates secretions that participate and obstruct the lumen = causing inflammation and degradation of the pancreas, liver, gall bladder, intestine.

Question 43

pancreatitis?

Answer 43

inflammation of the pancreas | caused by high levels of amylase (break down starch) and lipase (digest fats) in the blood stream