Module 6: Metabolism And Enzymes

Question 1

What are polypeptides?

Answer 1

Polymers of amino acids.

Question 2

What is the first Law of Thermodynamics?

Answer 2

Energy can be transformed and transferred but it cannot be created or destroyed.

Question 3

What is the second Law of Thermodynamics?

Answer 3

Every energy transfer or transformation increases entropy of the system that it is in.

Question 4

What does ATP stand for?

Answer 4

Adenosine triphosphate

Question 5

What is metabolism?

Answer 5

The chemical processing of substances within a living cell or organism.

Question 6

What are catabolic reactions?

Answer 6

A type of metabolism.
Catabolic reactions break down complex molecules into simpler ones. This releases energy.

Question 7

What are anabolic reactions?

Answer 7

A type of metabolism.
Anabolic reactions build complex molecules from simple ones.
This uses energy.

Question 8

What is energy?

Answer 8

The ability/capacity to do work

Question 9

What are the two types of energy?

Answer 9

1. Kinetic energy. The energy of movement - objects in motion.
2. Potential energy. The potential to do work.
   E.g. a suspended object.

Question 10

What is chemical energy?

Answer 10

The potential energy within chemical bonds.

Question 11

What is Gibbs free energy?

Answer 11

The energy available after entropy - usable energy that is available to do work.

Question 12

What is the equation to calculate the change in free energy?

Answer 12

ΔG = ΔH - TΔS

Where ΔG (delta G) is the change in free energy.
ΔH is the total energy in the system (enthalpy).
ΔS is the energy lost to entropy.
And T is the absolute temperature in Kelvin.

Question 13

What is enthalpy?

Answer 13

The sum of a thermodynamic system’s internal energy and the product of its pressure and volume.

Question 14

What is entropy?

Answer 14

The state of disorder, randomness, or uncertainty in a thermodynamic system. A measure of the amount of energy not available to do work.

Question 15

What is thermodynamics?

Answer 15

Physics that deal with the relationships and conversions between heat and other forms of energy.

Question 16

What type of reactions has a ΔG<0

Answer 16

A reaction that releases energy has a negative ΔG.
This is an exergonic reaction.

Question 17

What is an exergonic reaction?

Answer 17

A reaction where energy is exiting the system.
This is also known as a spontaneous reaction because they can occur without needing energy input.

Question 18

What is a endergonic reaction?

Answer 18

A reaction that stores energy.
Requires an energy input and has a positive ΔG value.
Non-spontaneous.

Question 19

What is activation energy?

Answer 19

The amount of energy input necessary does chemical reactions to occur.
Ea

Question 20

What is an open system?

Answer 20

A system where energy can transfer between the system and its surroundings.

Question 21

What is a closed system?

Answer 21

A system where energy can NOT transfer between the system and its surroundings.

Question 22

What is the structure of ATP?

Answer 22

Adenosine is bound to 3 phosphate groups.

Question 23

What is adenosine?

Answer 23

A nucleoside (nucleotide without a phosphate group) that consists of the nitrogenous base adenine and a 5-carbon sugar, ribose.

Question 24

What is the hydrolysis reaction of ATP?

Answer 24

ATP + H2O → ADP + Pi + free energy

Where Pi is an inorganic phosphate group.

Question 25

What is the equation of ATP formation?

Answer 25

ADP + Pi + free energy → ATP + H2O Where Pi is an inorganic phosphate group.

Question 26

What is phosphorylation?

Answer 26

The attachment of a phosphate group to a molecule or ion.

Question 27

How does ATP provide energy?

Answer 27

Energy coupling and phosphorylation through an exergonic reaction. ATP is a highly unstable molecule that dissociates quickly. It releases energy by breaking one of its phosphate bonds - the created products have much lower free energy than the reactants (ATP and H2O). With most ATP hydrolysis cases, the ATP phosphate transfers onto another molecule, triggering a conformational change.

Question 28

What is an enzyme?

Answer 28

A molecule that catalyses biochemical reactions. Almost all enzymes are proteins comprised of amino acid chains. They lower activation energy for chemical reactions.

Question 29

What is a catalyst?

Answer 29

A substance that modifies and increases the rate of a reaction without being consumed in the process.

Question 30

Where does a substrate bind?

Answer 30

The enzyme's active site.

Question 31

What factors affect enzyme regulation? What does this cause?

Answer 31

If an enzyme is outside optimal conditions, it may denature. 1. Temperature. 2. pH. 3. Regulatory molecules (inhibitor or activator molecules). 4. Cofactors (non-proteins helpers that activate enzymes). 5. Compartmentalisation (enzymes stored in specific compartments can be prevented from acting on certain substances). 6. Feedback inhibition (regulation using a product of the enzyme).

Question 32

How do enzymes facilitate reactions?

Answer 32

They bring the substrates together in the optimal orientation. They create an optimal environment for the reaction to occur. Enzymes can also take part in the chemical reaction themselves, further lowering activation energy.

Question 33

What complex lowers activation energy and promotes rapid reaction progression?

Answer 33

The enzyme-substrate complex.

Question 34

What is an allosteric site?

Answer 34

A site on the enzyme other than the active site. Where non-competitive inhibitors bind.

Question 35

What are the types of enzyme inhibitors?

Answer 35

1. Competitive inhibitors. Bind to the active site. 2. Non-competitive inhibitors. Binds to an allosteric site, NOT the active site. Harder to remove.

Question 36

What is an allosteric activator?

Answer 36

An effector molecule that binds to an enzyme at a location away from the active site, inducing a conformational change that increases the enzyme's affinity for its substrate/s.

Question 37

What is a cofactor?

Answer 37

An inorganic ion, or non-protein chemical compound, helper molecule that assists enzymes. E.g. iron (Fe+) and magnesium (Mg+).

Question 38

What is a coenzyme?

Answer 38

An organic helper molecule required for enzyme action. The most common coenzymes are dietary vitamins.

Question 39

What enzyme builds DNA molecules?

Answer 39

DNA polymerase.

Question 40

How does vitamin C acts as a coenzyme?

Answer 40

Vitamin C is a coenzyme for multiple enzymes that take part in building collagen (an important connective tissue component).

Question 41

What is the difference in structure for most allosterically regulated enzymes?

Answer 41

They are comprised of more than one polypeptide, meaning they have more than one protein subunit.

Question 42

What is feedback inhibition in metabolic pathways?

Answer 42

Feedback inhition involves using a reaction product to regulate its own further production.