Enzymes- lecture #9

Question 1

what does metabolism do?

Answer 1

manages all material and energy resources of the cell

Question 2

what is a catabolic pathway?
_____,_____,

Answer 2

releases energy as ATP
breaks down large molecules/polymers
in a useable form

Question 3

what is an anabolic reaction?
_____,_____,

Answer 3

uses energy
builds large molecules/polymers
unfavorable because it uses energy

Question 4

what do all metabolic practices rely on?

Answer 4

enzymes, in order to make them happen efficiently

Question 5

what can energy be used to do?

Answer 5

work (such as rearrange matter)

Question 6

what 2 laws govern thermodynamics?

Answer 6

energy can be transferred and transformed but may not be created nor destroyed
some energy is lost as heat

Question 7

what is a spontaneous process?

Answer 7

(-) delta G (more stable)
creates disorder
exergonic
releases energy (heat)

Question 8

why do we want disorder?

Answer 8

because the molecules will interact more and hit each other, creating heat

Question 9

what is a non spontaneous process?

Answer 9

(+) delta G (less stable)
creates order
endergonic
requires energy (absorbs)

Question 10

do we want enthalpy (delta H) to be positive or negative? why?

Answer 10

we want enthalpy to be negative, because it will release heat

Question 11

is the entropy of the universe always increasing or decreasing?

Answer 11

entropy of the universe is always increasing

Question 12

does (+) entropy create disorder or order?

Answer 12

it creates disorder, we want this

Question 13

what happens to entropy when catabolic reactions release energy?

Answer 13

entropy increases

Question 14

what happens to entropy when anabolic reactions require energy?

Answer 14

entropy decreases

Question 15

enzymes functions to do what?

Answer 15

Lower the activation energy of a reaction allowing products to be produced more quickly

Question 16

what else can increase the rate of a reaction? why do we not want it to happen all the time?

Answer 16

heat, however, all reactions would see an increase in rate (non specific) so we don’t want this to happen all the time

Question 17

why is activation energy needed?

Answer 17

to destabilize the bonds of the reactants so they are readily able to break

Question 18

what is the process of a bond breaking?

Answer 18

heat gets absorbed to provide energy
(energy required to break a paperclip)
transition state is reached when enough energy is absorbed
(bending the paperclip at first, hard to do)
bonds eventually break and energy will be released
(gets easier to bend and eventually snaps)

Question 19

process of a substrate entering an enzyme

Answer 19

enzyme begins with empty active site, substrate enters into the active site (attaching with weak bonds), the strained substrate bond reacts with water (converting reactants to products), enzyme releases the product, enzyme is ready to catalyze a new reaction

Question 20

why do enzymes act on a particular substrate?

Answer 20

shape of the active site caters to the shape of the specific substrate

Question 21

what is the induced fit hypothesis?

Answer 21

substrate binds to an active site and both the substrate and active site change creating an ideal, close fit
this strains substrate bonds making them easier to break

Question 22

what does the enzyme need to get the reactant out of the product?

Answer 22

needs some energy

Question 23

how many substrates do enzymes act on per second?

Answer 23

acts on thousands or even millions of substrate molecules per second

Question 24

what is critical to enzymes function?

Answer 24

shape

Question 25

what may affect the shape of the enzyme?

Answer 25

temperature and pH value

Question 26

what happens if the temperature is higher then optimal value?

Answer 26

denatures the enzyme rendering it, non -functional

Question 27

what happens if the pH is slightly higher or lower then optimal pH?

Answer 27

enzyme function is impaired

Question 28

why do most enzymes require cofactors?

Answer 28

coenzymes help recruit substrates

Question 29

what are competitive inhibitors?

Answer 29

resemble the substrate
block the substrate from entering the active site
irreversible

Question 30

what are non-competitive inhibitors?

Answer 30

do not resemble the substrate
bind to the enzyme but not in the active site
reversible

Question 31

what is an important metabolic regulator

Answer 31

feedback inhibition

Question 32

what is feedback inhibition?

Answer 32

when a cell produces more product then it needs
the product can inhibit the enzyme

Question 33

The hydrolysis of ATP forming ADP and Pi has a G= -30.5kJ/mol. What can you conclude about ATP hydrolysis?

Answer 33

endergonic reaction
spontaneous reaction