Energy and Enzymes

Question 1

Energy (what it is and forms)

Answer 1

• a force that can accomplish work
• 2 major forms
  
  • potential
  • kinetic

Question 2

Potential energy (what it is and examples)

Answer 2

• energy of position (stored energy)

- ex: chemical energy (in bonds)

Question 3

Kinetic energy (what it is and example)

Answer 3

• energy of motion

- ex: mechanical energy

Question 4

Metabolism (what it is and types)

Answer 4

• sum of all chemical reaction in a living organism
• includes
  
  • anabolism
  • catabolism

Question 5

Anabolism

Answer 5

• Biosynthesis reactions: building

- Endergonic: requires energy

Question 6

Catabolism

Answer 6

• degrative reactions: breaking down

- exergonic: energy releasing

Question 7

Chemical reactions (components and directions)

Answer 7

Components:
  -Substrate: what goes in (reactant)
  -product: what comes out
Directions:
  -Forward
  -reverse

Question 8

Factors affecting chemical reactions

Answer 8

1. law of mass action
2. activation energy
3. enzymes

Question 9

Law of mass action

Answer 9

• forward reactions
• higher reactants= higher products
• high product= slow down making of product

Question 10

Activation energy

Answer 10

• minimum energy required for reactants to overcome activation energy barrier –> transition state –> product
• Sources:
  
  • collision from other molecules

Question 11

Enzymes (structure, function)

Answer 11

Structure:
  -protein based molecules
  -substrate specific 
Function:
  -reduce activation energy
  -biological catalysts:
      -speed up reactions
      -does not get used up or changed

Question 12

Models for Enzyme Binding

Answer 12

1. lock and key mechanism

2. induced fit model

Question 13

Lock and key mechanism

Answer 13

• substrate fits an enzyme like a key to a lock

- problem: doesn’t explain reversible reactions

Question 14

Induced fit model

Answer 14

• substrates approximately fit enzyme

- after binding –> conformational change for a better fit

Question 15

How enzymes work (steps)

Answer 15

-enzyme binds with a substrate converting them to products

1. substrate contacts active site of the enzyme
2. enzyme- substrate complex forms
3. substrate is transformed, broken down, or compounded with other substrates
4. transformed substrate (products) released
5. unchanged enzyme free to interact with other substrates

Question 16

Enzyme sites

Answer 16

1. active site: where substrate binds

2. allosteric site: where molecules other than the substrate bind

Question 17

Types of enzymes

Answer 17

1. simple enzymes: proteins with catalytic activity

2. holoenzymes: conjugated enzymes

Question 18

Holoenzymes (protein and nonprotein portion)

Answer 18

Protein portion: apoenzyme
nonprotein portion:
-cofactor: inorganic ions (zinc, iron, magnesium, calcium)
-coenzyme: organic molecules (vitamins/minerals) ex: NAD+, NADP+, FAD, coenzyme A

Question 19

Factors influencing enzymatic rate (6)

Answer 19

1. enzyme concentration
2. substrate concentration
3. temperature
4. pH
5. enzyme catalytic rate
6. affinity

Question 20

Enzyme catalytic rate

Answer 20

inherent speed of an enzyme

Question 21

Substrate concentration

Answer 21

increasing substrate, increasing activity until saturation

-saturation: enzymes active sites are filled with substrate

Question 22

Enzyme concentration

Answer 22

increase in enzymes= increase in maximum rate

Question 23

Affinity

Answer 23

How tightly a substrate binds to an active site

high affinity –> increase reaction rates

Question 24

Temperature

Answer 24

• enzymes have an optimal temperature
• increases rate of collision and reaction
• too much –> denature enzyme

Question 25

pH

Answer 25

• enzymes have an optimal pH

- extreme pH (acidic or basic) –> denature enzyme

Question 26

Enzyme regulation

Answer 26

1. allosteric regulation

2. inhibitors

Question 27

Allosteric regulation (what it is and examples)

Answer 27

-modulators weakly bind to allosteric site

1. activator: increase catalytic rate, increase affinity to substrate
2. inhibitor: decreases enzymatic activity

Question 28

Inhibitors

Answer 28

1. competitive: chemicals that bind to the active site
   ex: penicillin, sulfanilamide
2. non-competitive: chemicals that bind to the allosteric site or cofactors
   ex: cyanine, fluoride