Lecture 10 - Energy, Enzymes, and Metabolism

Question 1

Energy: During ____ reactions, energy is ____ and _____. A ____ reaction is when ____ are _____ and _______ with other atoms.

Answer 1

chemical; consumed and released.

chemical; atoms; combined; recombined

Question 2

Two types of chemical reactions:

Answer 2

1. Anabolic reactions: complex molecules are made from simple molecules, energy input is required.
2. Catabolic reactions: complex molecules are broken down to simpler ones, energy is released.

Question 3

Two types of energy:

Answer 3

1. Potential energy: energy stored as chemical bonds, concentration gradient, charge imbalance, etc.
2. Kinetic energy: the energy of movement.

Question 4

Types of energy: chemical example

Electrons can be located in regions of ___ _____ energy, or ___ ____ energy.

Answer 4

high potential; low potential

Question 5

Gibbs Free Energy: The _____ of a reaction is determined by the _____ in Gibbs free energy of a reaction. The ____ in Gibbs free energy is the sum of the change of ______ ___ (__ or _______) and the change in _______ (__ or ____)

Answer 5

energy; change

change; usable energy (deltaH or enthalpy); disorder (deltaS or enthalpy)

Question 6

If deltaG is negative, ____ _____ is ________ (__________/__________)
If deltaG is positive, ____ ______ is _______ (_____________).

Answer 6

free energy; released; (exergonic/spontaneous)

free energy; required; (endergonic)

Question 7

Catabolism is an example of ___________ ______.

Anabolism is an example of __________ ______.

Answer 7

exergonic reaction

endergonic reaction

Question 8

First Law of Thermodynamics

Answer 8

Energy cannot be created nor destroyed; just transformed or converted into another type of energy.

Question 9

Second Law of Thermodynamics

Answer 9

The total entropy (disorder) of the universe is always increasing.

Question 10

Chemical reactions: Equilibrium (2)

Answer 10

• a reaction can be reversible, and the forward and reverse reactions will continue until reaching equilibrium (deltaG = 0)
• if the reaction is spontaneous, the reaction will tend to the products (higher concentration of products than reactants at equilibrium)

Question 11

Use ___ to drive endergonic reactions.

Answer 11

ATP (adenosine triphosphate)
ATP is energy currency (used to drive non-spontaneous reactions)
It is a component to DNA

Question 12

Hydrolysis of ATP is exergonic (2)

Answer 12

• phosphate groups have a negative charge and repel each other - the energy needed to get them close enough to bond is stored in the P-O bond.
• the free energy of the P-O bond is much higher than the energy of the O-H bond that forms after hydrolysis.

Question 13

Coupling reactions:
The formation of ATP is ______ and is coupled with _____ _____.
The hydrolysis of ATP is ______ and is coupled with _____ ____.

Answer 13

endergonic; exergonic reactions

exergonic; endergonic reactions.

Question 14

ATP drives ___-____________ reactions. Production of ____________ requires ___; degradation of macromolecules can be used to ______ _____.

Answer 14

non-spontaneous
macromolecules; ATP
create ATP

Question 15

Oxidation/Reduction reactions

Answer 15

reduction (oxidizing agent): gain of one or more electrons by an atom, ion, or molecule (becomes more negative)
oxidation (reducing agent): loss of one or more electrons by an atom, ion, or molecule (becomes more positive)

Question 16

Oxidation of ATP: Oxidation of molecules drives the production of ___. _____ is the most molecule used in cells. _______ loses electrons to become oxidized and ______ gains them to become reduced.

Answer 16

ATP
Glucose
Glucose; oxygen

Question 17

NADH is also used to store energy. _______ ____ is a key ________ _____ in redox reactions.

Answer 17

Coenzyme NAD+; electron carrier

Question 18

Production of ATP: Oxidation of glucose can occur by __ different pathways

Answer 18

three

1. glycolysis
2. cellular respiration
3. fermentation

Question 19

Glycolysis (10 steps, 3 phases)

Answer 19

Results in conversion of one glucose into 2 pyruvates and 2 ATP and 2 NADH.
1-3. Phase 1 - preparatory phase, with consumption of 2 ATPs
4-5. Phase 2 - cleavage phase, cyclic glucose splits into two chain molecules.
6-10. Phase 3 - payoff phase, with production of 4 ATP and 2 NADH

Question 20

Pyruvate oxidation (3)

Answer 20

• occurs in mitochondrial matrix
• produces acetate and CO2
• produces 2 NADH (1 from each pyruvate oxidized)

Question 21

Citric cycle (3)

Answer 21

• acetyl group is completely oxidized to 2 molecules of CO2
• energy released is captured by ADP, NAD+, FAD, and GDP
• produces 6 NADH (3 from each acetyl group oxidized)

Question 22

Glucose oxidation overview: Overall the oxidation of one glucose molecules yields (4)

Answer 22

• 6 CO2
• 10 NADH
• 2 FADH2
• 4 ATP

Question 23

Oxidative phosphorylation: The starting molecules (_______ ___ and ________ _______ ______) must be replenished. The ________ ________ are ______ and they must be _______. This occurs via oxidative phosphorylation which has ____ stages: _______ ________ and ________.

Answer 23

acetyl coA; oxidized electron carriers
electron carriers; reduced; reoxidized
two; electron transport; chemiosmosis

Question 24

Electron transport (2)

Answer 24

• electrons from NADH and FADH2 pass through the respiratory chain of membrane-associated carriers.
• electron flow results in a proton concentration gradient across the inner mitochondrial membrane.

Question 25

Chemiosmosis: ____ flow back across the membrane through a channel protein ____ ______, which couples the __________ with ___ ________.

Answer 25

electrons; ATP synthase; diffusion; ATP synthesis.

Question 26

Electron transport: The _______ ______ is located in the _____ ____ ____________ ________. Energy is released as electrons are passed between ________. ____ are also actively transported. ________ accumulate in the ____________ _______ and create a __________ ______ and ___________ __________.

Answer 26

respiratory chain; folded inner mitochondrial membrane.
carriers
Protons
Protons; intermembrane space; concentration gradient; charge difference.

Question 27

Chemiosmosis: Diffusion of _____ back across the membrane is coupled to ____ _________ which is also called __________.

Answer 27

protons; ATP synthesis; chemiosmosis.

Question 28

Molecular mechanism of ATP synthesis (2)

Answer 28

• ATP synthase is a molecular motor with two parts: Fo unit is the transmembrane H+ channel. F1 unit projects into the mitochondrial matrix and rotates to expose active sites for ATP synthesis.

Question 29

After electron transport and oxidative phosphorylation, one glucose produces a net of ____ ATPs

Answer 29

32

Question 30

Anaerobic respiration

Answer 30

• many bacteria and archaea have evolved pathways that allow them to exist where O2 is scarce or absent, by using other electron acceptors.
• without O2, some ATP can be produced by glycolysis and fermentation. Fermentation occurs in the cytosol. NAD+ is regenerated to keep glycolysis going.

Question 31

Lactic acid fermentation (5)

Answer 31

• pyruvate is the electron acceptor and lactate is the product.
• occurs in microorganisms and some muscle cells.
• during active exercise, O2 cannot be delivered fast enough for aerobic respiration.
• muscle cells then break down glycogen and carry out lactic acid fermentation
• when lactate builds up, the increase in H+ lowers pH and causes muscle pain.

Question 32

Alcohol fermentation (3)

Answer 32

• yeast and some plant cells
• requires two enzymes to metabolize pyruvate to ethanol.
• used to produce alcoholic beverages.
  C6H12O6 + 2 ADP + 2 Pi -> 2 ethanol + 2 CO2 + 2 ATP

Question 33

Fermentation vs. Cellular Respiration (2)

Answer 33

• cellular respiration yields more energy than fermentation

- Glycolysis plus fermentation = 2 ATP while Glycolysis plus cellular respiration = 32 ATP