Lecture 10 - Energy, Enzymes, and Metabolism Flashcards
Energy: During ____ reactions, energy is ____ and _____. A ____ reaction is when ____ are _____ and _______ with other atoms.
chemical; consumed and released.
chemical; atoms; combined; recombined
Two types of chemical reactions:
- Anabolic reactions: complex molecules are made from simple molecules, energy input is required.
- Catabolic reactions: complex molecules are broken down to simpler ones, energy is released.
Two types of energy:
- Potential energy: energy stored as chemical bonds, concentration gradient, charge imbalance, etc.
- Kinetic energy: the energy of movement.
Types of energy: chemical example
Electrons can be located in regions of ___ _____ energy, or ___ ____ energy.
high potential; low potential
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 ____)
energy; change
change; usable energy (deltaH or enthalpy); disorder (deltaS or enthalpy)
If deltaG is negative, ____ _____ is ________ (__________/__________)
If deltaG is positive, ____ ______ is _______ (_____________).
free energy; released; (exergonic/spontaneous)
free energy; required; (endergonic)
Catabolism is an example of ___________ ______.
Anabolism is an example of __________ ______.
exergonic reaction
endergonic reaction
First Law of Thermodynamics
Energy cannot be created nor destroyed; just transformed or converted into another type of energy.
Second Law of Thermodynamics
The total entropy (disorder) of the universe is always increasing.
Chemical reactions: Equilibrium (2)
- 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)
Use ___ to drive endergonic reactions.
ATP (adenosine triphosphate)
ATP is energy currency (used to drive non-spontaneous reactions)
It is a component to DNA
Hydrolysis of ATP is exergonic (2)
- 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.
Coupling reactions:
The formation of ATP is ______ and is coupled with _____ _____.
The hydrolysis of ATP is ______ and is coupled with _____ ____.
endergonic; exergonic reactions
exergonic; endergonic reactions.
ATP drives ___-____________ reactions. Production of ____________ requires ___; degradation of macromolecules can be used to ______ _____.
non-spontaneous
macromolecules; ATP
create ATP
Oxidation/Reduction reactions
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)
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.
ATP
Glucose
Glucose; oxygen
NADH is also used to store energy. _______ ____ is a key ________ _____ in redox reactions.
Coenzyme NAD+; electron carrier
Production of ATP: Oxidation of glucose can occur by __ different pathways
three
- glycolysis
- cellular respiration
- fermentation
Glycolysis (10 steps, 3 phases)
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
Pyruvate oxidation (3)
- occurs in mitochondrial matrix
- produces acetate and CO2
- produces 2 NADH (1 from each pyruvate oxidized)
Citric cycle (3)
- 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)
Glucose oxidation overview: Overall the oxidation of one glucose molecules yields (4)
- 6 CO2
- 10 NADH
- 2 FADH2
- 4 ATP
Oxidative phosphorylation: The starting molecules (_______ ___ and ________ _______ ______) must be replenished. The ________ ________ are ______ and they must be _______. This occurs via oxidative phosphorylation which has ____ stages: _______ ________ and ________.
acetyl coA; oxidized electron carriers
electron carriers; reduced; reoxidized
two; electron transport; chemiosmosis
Electron transport (2)
- 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.
Chemiosmosis: ____ flow back across the membrane through a channel protein ____ ______, which couples the __________ with ___ ________.
electrons; ATP synthase; diffusion; ATP synthesis.
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 ___________ __________.
respiratory chain; folded inner mitochondrial membrane.
carriers
Protons
Protons; intermembrane space; concentration gradient; charge difference.
Chemiosmosis: Diffusion of _____ back across the membrane is coupled to ____ _________ which is also called __________.
protons; ATP synthesis; chemiosmosis.
Molecular mechanism of ATP synthesis (2)
- 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.
After electron transport and oxidative phosphorylation, one glucose produces a net of ____ ATPs
32
Anaerobic respiration
- 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.
Lactic acid fermentation (5)
- 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.
Alcohol fermentation (3)
- 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
Fermentation vs. Cellular Respiration (2)
- cellular respiration yields more energy than fermentation
- Glycolysis plus fermentation = 2 ATP while Glycolysis plus cellular respiration = 32 ATP
