Metabolic Processes Flashcards
Thermodynamics
The study of the energy changes in a system.
Surroundings are defined as the universe outside a system
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First law of thermodynamics
Energy cannot be created or destroyed.
Law of conservation of energy → the same amount of energy is maintained during any process.
All energy that exists now has existed since the Big Bang.
Second Law of Thermodynamics
The entropy of a system will increase over time.
Only applies to closed systems.
Catabolism
The process of breaking down larger molecules to smaller molecules, which results in a net release of energy.
Anabolism
Is the process of forming larger molecules from smaller molecules, which involves a net input of energy.
Kinetic Energy
Energy of motion.
Bond Energy
Energy required to break a bond.
Biological Systems
Are open systems (able to exchange energy and matter with the environment)
Can be highly ordered for survival (decrease in entropy).
G = H - TS
- G is the symbol for free energy: the energy associated with a chemical reaction that can be used to do work
- The difference in its enthalpy or energy in chemical bonds (H) and
- The product of the temperature and the entropy (S) of the system.
Gibbs free energy
The energy is that is available to do useful work
A reaction will spontaneously occur is ΔG < 0 (exergonic reaction)
A reaction will not spontaneously occur if ΔG > 0 (endergonic reaction)
Energy coupling
The transfer of energy from one reaction to another in order to drive the second reaction.
Photosynthesis
CO2 + H2O → C6H12O10 + O2 (anabolic)
Cellular respiration
C6H12O6 + O2 → CO2 + H2O + ATP + energy as heat (catabolic)
Glucose + oxygen -> carbon dioxide + water + ATP energy
Entropy
Disorder of a system, the increasing disorder of the universe. The universe held all of the potential energy it will ever have when it formed.
Since then, it has become increasingly more disordered, with every energy exchange increasing the amount of entropy. Entropy is continuously increasing.
Krebs cycle produces
2 ATP/GTP , 6 NADH, 2 FADH2, 4 CO2 (?)
Stages of Aerobic Respiration
Glycolysis (10 steps), Pyruvate Oxidation, Krebs cycle (8 steps), oxidative phosphorylation
Glycolysis Steps
Glucose, glucose 6-phosphate, fructose 6-phosphate, fructose 1,6-biphosphate, dihydroxyacetone phosphate, 1,3-biphosphoglycerate, 3-phosphoglycerate, Phosphoanolpyruvate, pyruvate
Know: glucose -> pyruvate (enzyme = pyruvate kinase)
- G3P, BPG, 3PG, 2PG, PEP
- Enzyme PFK
Glycolysis Produces
2 NAD+ converted into 2NADH, NET 2 ATP molecules
What is glycolysis?
Does not require oxygen, products necessary for following aerobic pathways. Occurs within the cytoplasm and produces two 3-carbon compounds. Compounds are then converted into 2 pyruvate molecules.
Acetyl-coenzyme A (CoA)
Produced during glycolysis and then carbon dioxide is released. Then enters the Krebs cycle.
What is the Krebs cycle?
Takes acetyl CoA (x2) and makes NADH + FADH2, carries electrons to the ETC. Occurs in the mitochondrial matrix
Steps of the Krebs cycle
Citrate, isocitrate, a-ketoglutarate, Succinyl-CoA, Succinate, Fumarate, Malate, oxaloacetate
Oxidative Phosphorilation
Occurs at the inner mitochondrial membrane, NADH and FADH2 are oxidised by electron carriers and proteins embedded in the membrane. Released energy is used to create a proton gradient in the inter-membrane space.
Pyruvate Oxidation
When oxygen is present, pyruvate produced from glycolysis is transported into the mitochondrial matrix
- A carbon is created off the pyruvate molecule and CO2 is released
- Remaining Acetyl group becomes associated with coenzyme A and forms acetyl-CoA
- Reaction is coupled with reduction of NAD+ to form NADH
Products before oxidative phosphprilation
- 4 ATP (2 glycolysis, 2 Krebs)
- 6 NADH (2 glycolysis, 2 pyruvate, 2 Krebs)
- 2 FADH2 (2 krebs)
Products in oxidative phosphorylation
NADH Total 30 ATP
FADH2 Total 4 ATP
- MAX 34 ATP
Enzymes in oxidative phosphorylation (weakest-strongest)
NADH dehydrogenase, succinate dehydrogenase, cytochrome b-c1 complex, cytochrome oxidase complex
Chemiosmosis
The process of moving ions (e.g. protons) to the other side of a biological membrane, and as a result, an electrochemical gradient is generated. This can then be used to drive ATP synthesis.
Electron Transport Chain
Chain of proteins and e- carriers that pass e- along in order of increasing electronegativity. Energy is used to pump H+ into the intermembrane space. H+ flows through ATP synthase attaching phosphate to ADP to make ATP. Last thing to get reduced is oxygen.
Lactate fermentation
Pyruvate is converted to lactate (or lactic acid when protonated) and reoxidized NAD+ (NAD+ can be used again in glycolysis).
Oxygen Debt
Amount of oxygen required to eliminate lactate is called oxygen debt.
Methanogens
Use ETC to generate a hydrogen ion gradient that provide energy. Uses hydrogen synthesised by other organisms as a source of energy and CO2 as e- acceptor.
Fermentation
In glycolysis, NAD+ is reduced to NADH and pyruvate molecules are made (and net 2 ATP). The process that occurs in age absence of oxygen in which NAD+ and pyruvate are recycled to produce more ATP.
Anoxic
Oxygen free
Ethanol Fermentation
Facultative anaerobes can function both aerobically and anaerobically. In absence of oxygen, yeast and bacteria convert pyruvate to ethanol and CO2 via ethanol fermentation.
