How cells harvest energy- Chapter 7 Flashcards
Autotrophs
Produce their own organic molecules (energy) through photosynthesis
Heterotrophs
Live on organic compounds produced by other organisims (autotrophs)
Cellular respiration
Series of reactions to extract energy from organic molecules
Oxidation
Loss of electrons
Dehydrogenations
Lost electrons accompanied by protons (a hydrogen atom is lost: 1 electron, 1 proton)
Redox reactions
Electrons carry energy from one molecule to another
NAD (Nicotinamide adenine dinucleotide)
Electron carrier that accepts 2 electrons and 1 proton to become NADH. Reaction is reversible.
Aerobic respiration
Final electron receptor is oxygen (O2)
Anaerobic respiration
Final electron acceptor is an inorganic molecule (not oxygen)
Fermentation
Final electron acceptor is an organic molecule
Aeroic Respiration Reaction
6CO2 + 6H2O → C6H12O6 + 6O2
Change in free energy (Delta G)- Aerobic respiration
ΔG= -686kcal/mol of glucose
Delta G in a cell
ΔG= -720 kcal/mol
Electron carriers
Soluble and membrane-bound carriers that can be easily oxidized and reduced. (Many types used)
ATP
Cells use ATP to drive endergonic reactions:
ΔG= -7.3kcal/mol
Substrate-level phosphorylation
Transfer phosphate grroup directly to ADP during glycosis
Oxidative phosphorylation
ATP synthase uses energy from a proton gradient
Pyruvate Kinase
Enzyme involved in substrate-level phosphorylation
Glycolysis
Converts 1 glucose to 2 pyruvate
Pyruvate oxidation
In presence of oxygen, pyruvate oxidized in mitochondria by multienzyme complex called pyruvate dehydrogenase.
Krebs cycle
Oxidizes the acetyl group from pyruvate
Regeneration of oxaloacetate
Process of regenerating oxaloacetate in Krebs Cycle.
Krebs Cycle
A key metabolic pathway that processes acetyl groups.
Energy yield from glucose oxidation
Glucose has been oxidized to 6 CO2, 4 ATP, 10 NADH, and 2 FADH
Electron Transport Chain
Series of memebrane-bound electron carriers embedded into inner mitochondrial membrane.
Krebs Cycle produces
- Releases CO2
- Reduction of NAD+ and FAD
- Production of ATP
ETC transfers electrons from _____ to _____
NADH to FADH
Chemiosmosis
Process where accumulation of protons in the intermemebrane space drive protons into matrix.
Chemiosmosis done via…
Diffusion, primarily through ATP synthase.
Bacteria- Theoretical energy yield
32 ATP per glucose
Eukaryotes- 30 ATP per glucose
Eukaryotes- Theoretical energy yield
30 ATP per glucose
Proton movement- NADH
Moves 10 H
Proton movement- FADH
Moves 6 H+
ATP production per carrier- NADH
Each NADH makes 2.5 ATP
ATP production per carrier- FADH
Each FADH makes 1.5 ATP.
Feedback inhibtion
Process where end product of metabolic pathway inhibits an earlier step.
Phosphofructokinase inhibition
Phosfru. is allosterically inhibited by ATP and citrate.
Pyruvate dehydrogenase inhibtion
Pyruvate dehydro. inhibited by high levels of NADH.
Citrate synthesis inhibition
Citrate synthetase is inhibited by high levels of ATP
Uncoupling of Electron Transport System
Multiple molecules can inhibit the electron transport system by making the membrane ‘leaky’ to H+ or preventing ATP synthase from producing ATP.
Fermentation
Process that uses organic molecules as final electron acceptor
Fermentation uses final electron acceptor to…
Regenerate NAD+
Methanogens
Organisms that reduce CO2 to CH4 (methane)
Sulfur bacteria
Bacteria that reduce inorganic sulfate to hydrogen sulfide
Ethanol fermentation
Occurs in yeast producing CO2, ethanol, and NAD+
Lactic Acid Fermentation
Occurs in animal cells, where electrons transferred from NADH to pyruvate to produce lactic acid.
Deamination
Process that prepares amino acids for energy production by removing amino group.
Catabolism of fat
Fats broken down to fatty acids and glycerol
Fatty acids in catabolism
Fatty acids converted to acetyl groups by B-oxidation.
Evolution of glycolosis
A pathway found in all living organisms that represents an early stage in the evolution of metabolism.
