Lecture 5: Energy, ATP, Enzymes

Question 1

What is metabolism?

Answer 1

All of the chemical reactions that take place in our body

Question 2

What is Anabolism?

Answer 2

Reactions that link simple molecules together into more complicated molecule

Question 3

What is Catabolism?

Answer 3

Breaks down complex molecules into simpler ones.

Question 4

Which requires energy anabolism or catabolism?

Answer 4

Anabolism

Question 5

Which releases energy anabolism or catabolism?

Answer 5

Catabolism

Question 6

How do cells acquire energy?

Answer 6

From their environment(ex. eating food)

Question 7

What law explains energy conversions?

Answer 7

Second Law of Thermodynamics

Question 8

What is the second law of thermodynamics?

Answer 8

The drive of energy to be evenly distributed/dispersed

Question 9

Two ways energy is dispersed into the environment?

Answer 9

1. Increasing disorder inside the cell
2. Increasing disorder outside the cell

Question 10

How can disorder be increased inside the cell?

Answer 10

-Doing a chemical reaction that increases the disorder of the chemicals inside the cell
-Ex. Breaking down highly ordered molecules such as polypeptides

Question 11

How can disorder be increased outside the cell?

Answer 11

-Releasing heat

Question 12

What is an increase of disorder inside a cell called?

Answer 12

Entropy (delta S)

Question 13

What is an increase of disorder outside a cell called?

Answer 13

Enthalpy (delta H)

Question 14

Equation for delta G?

Answer 14

delta G = delta H - T(delta S)

Question 15

What does a negative delta G indicate?

Answer 15

Energy is released/dispersed
-There is disorder inside the system
-Reaction is spontaneous

Question 16

What does a positive delta G indicate?

Answer 16

• Energy is required and the reaction cannot occur on its own

Question 17

What happens when heat is released and disorder is increased (spontaneous?)(Anabolic/Catabolic)

Answer 17

-ALWAYS spontaneous(delta H = -, delta S = +)
-Catabolic
-Exergonic

Question 18

What happens when heat is released and disorder decreases?(spontaneous?)

Answer 18

• Spontaneous at low temperatures (delta H = -, delta S = -)
• Non-spontaneous at high temperatures

Question 19

What happens when heat is used and disorder increases?(spontaneous?)

Answer 19

• Spontaneous at high temperatures (delta H = +, delta S = +)
• Non spontaneous at low temperatures

Question 20

What happens when heat is used and disorder decreases?(spontaneous?)

Answer 20

-NEVER spontaneous (delta H = +, delta S = -)
- Anabolic
-Endergonic

Question 21

How are endergonic reactions able to occur?

Answer 21

-By coupling endergonic reactions with exergonic reactions

Question 22

How is energy transferred in cells?

Answer 22

Through ATP

Question 23

How does ATP create free energy?

Answer 23

Through ATP hydrolysis
-ATP is converted into ADP and Pi and releases free energy

Question 24

Why is ATP used as energy currency?

Answer 24

Its ΔG is intermediate between what you gain in respiration and what you expend in anabolism

Question 25

Examples of anabolism reactions?

Answer 25

• DNA replications
• Protein synthesis
• Making of Starch

Question 26

Examples of catabolic reactions?

Answer 26

• Digestion of food
• Any hydrolysis reaction (ATP – ADP +Pi)

Question 27

True or False: Energy conversions always result in a state of more disorder.

Answer 27

True

Question 28

Explain complication 1 of thermodynamics(reversible reactions)

Answer 28

All reactions are reversible, therefore delta G is dynamic and changes depending on how much reactant and product is in the system
-Concentrations are necessary in order to find the true value of delta G

Question 29

What is delta G of ATP in a cell?

Answer 29

-12 kJ/mol

Question 30

Another complication of thermodynamics(not knowing reaction rates)

Answer 30

If you know delta G, you still do not know how fast the reaction will proceed
-Many exergonic reactions occur extremely slowly

Question 31

What do catalysts do?

Answer 31

Increase the rate of spontaneous reactions with negative delta G

Question 32

What is a catalyst?

Answer 32

A protein, called an enzyme
- Can sometimes be RNA’s

Question 33

How do enzymes work?

Answer 33

They lower the activation energy required for reactions to proceed

Question 34

What is an enzyme-substrate complex?

Answer 34

When a reactant(substrate) binds to the active site of an enzyme it creates an enzyme-substrate complex

Question 35

What is a transition state and how do enzymes get substrates there?

Answer 35

Transition: characterized by a lower activation energy.
After the substrate binds to the enzyme the enzyme undergoes a conformational bringing the substrate into a transition state

Question 36

What happens after the substrate leaves the enzyme?

Answer 36

The enzyme reverts back to its original shape

Question 37

What can induce the enzyme to transfer the substrate to the transition state?(3 ways)

Answer 37

1. Binding substrates in the correct orientation
2. Exposing the reactants to altered charge environments
3. Inducing strain on the substrate facilitating breaking of bonds

Question 38

Why is pH important to maintain in terms of enzymes and charged environments?

Answer 38

Enzymes may no longer be able to bring substrates to the transition state if there is too high of pH or too low of a pH due to a lack of charged environment

Question 39

What are cofactors?

Answer 39

• Anything that is not an amino acid
• Binds to enzymes and is necessary for enzyme activity

Question 40

When is an enzyme saturated?

Answer 40

When all of its active sites are full