Energy, Catalysis and Biosynthesis

Question 1

Second Law of Thermodynamics

Answer 1

Systems will change spontaneously toward arrangements with greater entropy. Therefore, the degree of disorder (entropy) will always increase over time.

Question 2

What is entropy?

Answer 2

The dispersal of energy

A campfire is an example of entropy. The solid wood burns and becomes ash, smoke and gases, all of which spread energy outwards more easily than the solid fuel.

Question 3

Why is entropy always increasing?

Answer 3

Changes towards ‘disorder’ are overwhelmingly more likely than those towards ‘order’.

Example: Releasing Heat
Everything done has an amount of inefficiency so energy gets loss in some way, increasing disorder to the system.

Question 4

If creating and growing requires ‘order’ in cells, how is the second law of thermodynamics obeyed?

Answer 4

In the process of cells growing and creating chemical functions, some energy is inevitably loss in the form of heat, increasing entropy

Question 5

What is the first law of thermodynamics?

Answer 5

Energy cannot be created or destroyed. They can be converted from one form to another.

Question 6

How do cells manage to create and maintain order despite ever increasing entropy?

Answer 6

Cells use a tremendous amount of energy to create and maintain order. Cells get their energy from light and food and convert them to a usable energy.

Question 7

Free Energy

Answer 7

Energy that can be harnessed to do work or drive chemical reactions

Question 8

What determines whether a chemical reaction can occur?

Answer 8

Delta G

Reactions that create disorder by decreasing the amount of free energy of the system because they are energetically favorable. Basically, a reaction can only occur if delta g is negative.

Energetically favorable reactions have a negative Delta G

Question 9

What does it mean for change in free energy to be zero

Answer 9

The reaction is at equilibrium, meaning the rate of the forward reaction equals the rate of the reverse reaction. All reactions tend to proceed towards equilibrium.

Note: the concentration of reactant and product may NOT be equal.

Question 10

How does delta g naught relate to K

Answer 10

It is directly proportional. If K is bigger, delta g naught is more negative, thus there is more free energy and more favorable.

Question 11

What is a coupled reaction?

Answer 11

A reaction where the the free energy of a favorable transformation and a unfavorable transformation join into a new reaction to drive unfavorable reaction.

Question 12

Coupled Reaction- Activated Carrier

Answer 12

Activated Carrier: ATP

Glucose + Fructose -> Sucrose = 23 kj/mol (unfavorable)

but when we add ATP
Glucose - ATP + Fructose -> Sucrose + P = -7.5 kj/mol (favorable)

Question 13

What is an activated carrier? What is it use for?

Answer 13

Small organic molecules that contain one or more energy-rich covalent bonds. In a cell setting, cells used activated carrier to carry out unfavorable reaction.

Question 14

What is a catabolic pathway?

Answer 14

Catabolic pathways are those that generate energy by breaking down larger molecules.
Energy is released when breaking down larger molecules

Question 15

What is an anabolic pathway?

Answer 15

Anabolic pathways are those that require energy to synthesize larger molecules. Anabolic pathway used the energy generated from catabolic pathway to synthesize larger molecules.

Anabolic pathway is powered by catabolic pathway.

Question 16

How does catabolic pathway contribute to creating order in cell?

Answer 16

The catabolic pathway break down foodstuff into smaller molecules, thereby generating
both a useful form of energy for the cell and some of the small molecules
that the cell needs as building blocks.

Question 17

How does anabolic pathway contribute to order in the cell?

Answer 17

Anabolic pathway use the generated energy (catabolic pathway produces energy when breaking down molecules ) to synthesize larger molecules.

Question 18

What is oxidation?

Answer 18

Losing an electron for another compound to gain an electron (reduction)

Question 19

What is reduction?

Answer 19

Gaining an electron

Question 20

How does cell obtain energy by the oxidation of organic molecule?

Answer 20

Cellular Respiration

Cellular respiration is an oxidative process where glucose is being oxidized. This produces energy for the cells.

Question 21

Hydrogenation

Answer 21

Hydrogenation: chemical reaction between a compound and H2.

Electron usually gets transfer with a proton. Therefore, an increase in the number of C–H bonds, in an organic molecule indicates a reduction

Question 22

Dehydrogenation

Answer 22

Chemical reaction that involves the removal of hydrogen, usually from an organic molecule.

Electron usually gets transfer with a proton. Therefore, a decrease in the number of C–H bonds, in an organic molecule indicates an oxidation.

Question 23

What are enzymes?

Answer 23

Proteins that binds onto substrate, responsible for its (nearly all) chemical transformation that occur in cell.

Question 24

What is an activation energy?

Answer 24

The minimum amount of energy that is required to activate atoms or molecules to a condition in which they can undergo chemical transformation or physical transport.

Question 25

What are substrates?

Answer 25

Molecules that enzymes bind to

Question 26

What must cells need in order to undergo chemical reactions, without the aid of raising their temperature?

Answer 26

Cells require enzyme. With heat, the activation is provided. However, because cells cannot raise their temperature, they require the aid of enzymes to reduce the activation rate for cells to undergo a chemical reaction. Even energetically favorable reaction need a boost which enzymes provide.

Question 27

What is the relationship between heat and enzymes?

Answer 27

It is true that heat raise the rate of enzyme activity. However, there is an optimal temperature for enzymes. Boiling enzyme will not cause it to be more productive; it will denature it.

Question 28

Characteristic of Enzymes

Answer 28

-Enzymes increase the rate of reactions by reducing the activation energy
- Each type of enzyme is highly specific, catalyzing only a single type of reaction.
-Does not change the equilibrium point of a reaction; enzymes accelerate the forward and reverse reaction at the same rate

Question 29

How can we measure enzyme performance?

Answer 29

By measuring how rapidly enzymes can process its substrate

Question 30

How do we measure an enzyme’s performance to a substrate?

Answer 30

Using a test tube, a fixed amount of enzymes and different concentration of substrates are added. Then, the maximum velocity of an enzyme can be measured

Question 31

What does Michaelis constant tell us?

Answer 31

Amount of substrate that allows the enzyme to reach half of its maximal speed.

It also tells us the enzyme’s affinity to its substrate.
A small KM indicates that a substrate binds very tightly to the enzyme. A big KM indicate weak binding.

Question 32

What are competitive inhibitors?

Answer 32

Molecules that block enzyme activity by competing with the substrate for the same binding site on the enzyme. They resemble the substrate enough to tie up the enzyme, but they differ enough in structure to avoid getting converted to product.

Question 33

Why don’t competitive inhibitors change the maximum velocity of enzymes?

Answer 33

Because the addition of more substrate will swamp the enzyme active site, out-competing the inhibitor, and eventually allowing the uninhibited Vmax to be achieved.

Question 34

How does Competitive inhibitors affect Km?

Answer 34

Increase KM
Because of competition with the inhibitor for the active site, more substrate must be added to achieve a half-maximal catalytic rate.

Question 35

What are Non-Competitive Inhibitors

Answer 35

Molecules that bind on an enzyme’s allosteric site, changing the shape of the enzyme so that it no longer function.

Substrate and non-competitive inhibitors can both simultaneously bind to the enzyme.

Question 36

How do non-competitive inhibitors affect KM

Answer 36

Noncompetitive inhibitors do NOT change because inhibitor binds the free enzyme and the enzyme-substrate complex with the same affinity.

Question 37

How do non-competitive inhibitors affect the maximal velocity of an enzyme?

Answer 37

Noncompetitive inhibitors lower Vmax because they inhibit the enzyme even if more substrate is added.