Chapter 7 - How Cells Harvest Energy Flashcards
proton
Positively-charged particle of an atom - H+
NAD+
- nicotinamide adenosine dinucleotide
- one of the most important electron (e-) acceptor/carriers
- a cofactor that accepts a pair of e- and a proton (H) to create NADH
- composed of two nucleotides bound together by the phosphates
NADH
- NAD+ that has accepted 2 e- and one proton
* Reaction is reversible: can release 2 e- and 1 proton to become NAD+ again
FADH2
- FAD that has accepted 2 e-
* Bound to its enzyme in the inner mitochondrial membrane, so only releases e- to the electron transport chain.
G-3-P
- Step 4/5 product in glycolysis.
Krebs Cycle (summary description and location)
- 9-step process to reduce the acetyl group from Pyruvate Oxidation
- Occurs in the matrix of the mitochondria
- Otherwise known as the citric acid cycle
- When the cell’s ATP concentration is high, the process shuts down and acetyl-CoA is channeled into fat synthesis.
Glycolysis (definition/description)
- The break-down of glucose in a cell for metabolism
- E- of C-H bonds are stripped off in a series of reactions (including the Krebs cycle)
- Occurs in the cytoplasm
cytoplasm
Material inside a cell, not including the nucleus.
oxaloacetate
- “Feeder” molecule (4-carbon) that reacts with acetyl-CoA to start the Krebs Cycle
- Also the Step 9 product of the Krebs Cycle
alpha-ketoglutarate
Step 4 product of the Krebs Cycle, a 5-carbon molecule
acetyl-CoA
- The end product of Pyruvate Oxidation
- Feeds the Krebs Cycle
- consists of 2 carbons from pyruvate attached to coenzyme A
citric acid
- Step 1 product of the Krebs Cycle, a 6-carbon molecule
electron transport system
- Series of e- carriers to store energy from oxidation reactions
- Located in the inner membrane of the mitochondrion.
- Electrons from NADH and FADH2 are transferred from complex to complex, with some e- energy lost at each transfer, used to pump H+ out of matrix to inter-membrane space.
fumarate
Step 7 product of the Krebs Cycle, a 4-carbon molecule
malate
Step 8 product of the Krebs Cycle, a 4-carbon molecule
succinate
Step 6 product of the Krebs Cycle, a 4-carbon molecule
succinyl-CoA
Step 5 product of the Krebs Cycle, a 4-carbon molecule
isocitrate
Step 2/3 product of the Krebs Cycle, a 6-carbon molecule
aerobic
involving oxygen (final electron acceptor is O)
anaerobic
not involving oxygen (final electron acceptor is an inorganic molecule other than O)
pyruvate
- Step 10 product of glycolysis.
- The further fate of pyruvate depends on oxygen availability:
- When oxygen is present, pyruvate is oxidized to acetyl-CoA which enters the Krebs cycle
- Without oxygen, pyruvate is reduced in order to oxidize NADH back to NAD+
glucose 6-phosphate
- Step 1 product of glycolysis
glucose has gained a phosphate from ATP
fructose 6-phosphate
- Step 2 product of glycolysis
glucose 6-phosphate has been reorganized
citric acid cycle
Also known as the Krebs Cycle
fructose 1,6-biphosphate
- Step 3 product of glycolysis
substrate level phosphorylation
- The creation of ATP from ADP by transferring a phosphate group from another molecule
(Endergonic, enzyme-facilitated reaction where PEP and ADP bind to an enzyme’s active sites and a phosphate group is transferred from PEP to ADP.)
ATP synthase
- An enzyme that facilitates the synthesis of ATP through oxidative phosphorylation (a second method to substrate-level - energy to transfer the phosphate comes from a proton gradient).
- A membrane-bound enzyme that uses the energy of the proton gradient to synthesize ATP from ADP + Pi
cellular respiration
The process by which energy is harvested through the oxidation of organic compounds, extracting energy from the chemical bonds.
The final e- acceptor in aerobic respiration
Oxygen
1,3-Biphosphoglycerate (BPG)
- Step 6 product of glycolysis.
3-Phosphoglycerate (3PG)
- Step 7 product of glycolysis.
2-Phosphoglycerate (2PG)
- Step 8 product of glycolysis.
Phosphoenolpyruvate (PEP)
- Step 9 product of glycolysis.
Glycolysis Steps
- Step 1: Phosphate group added to glucose by ATP (to ADP). Produces Glucose 6-phosphate
- Step 2: Rearrange Glucose 6-phosphate into Fructose 6-phosphate. Produces Fructose 6-phosphate
- Step 3: Phosphate group added to Fructose 6-phosphate by ATP (to ADP). Produces Fructose 1,6-biphosphate
- Step 4/5: Fructose 1,6-biphosphate is split into two 3-carbon molecules. Produces one G3P and one that is converted into G3P in a second reaction.
- Step 6: Two G3P molecules are each oxidized by NAD+ and a P-group added. Produces 2 NADH and 2 BPG.
- Step 7: One phosphate group removed from each BPG by ADP. Produces two ATP and two 3PG.
- Step 8: Two 3PG molecules rearranged into two 2PG.
- Step 9: Dehydration reaction on two molecules of 2PG. Produces 2 molecules of water and two PEP.
- Step 10: One phosphate group removed from each of two molecules of PEP by ADP. Produces two ATP and two Pyruvate.
Phosphorylation
Chemical process to add a phosphate group to an organic molecule.
Glycolysis: summary of 1st 5 reactions and 2nd 5 reations
- 1st 5: Convert a molecule of glucose into two molecules of G3P.
- 2nd 5: Convert two molecules of G3P into two molecules of pyruvate.
Krebs Cycle output
- 2 CO2
- 1 ATP
- 3 NADH (3 pairs of e-)
- 1 FADH2 (1 pair of e-)
Krebs Cycle steps
- Step 1: (Condensation) Oxaloacetate reacts with acetyl-CoA to produce citrate.
- Steps 2/3: (Isomerization) 2-step process to rearrange citrate into an isomer isocitrate.
- Step 4: (1st Oxidation) Isocitrate is oxidized, producing alpha-ketoglutarate, one CO2, and one NADH.
- Step 5: (2nd Oxidation) alpha-ketoglutarate is oxidized, producing succinyl-CoA, one CO2, and one NADH.
- Step 6: (Substrate-level Phosphorylation) Succinyl-CoA is cleaved into two molecules and the energy released bonds a phosphate to GDP, which releases it to ADP, producing succinate and one ATP.
- Step 7 (3rd Oxidation) Succinate is oxidized, producing fumarate and one FADH2.
- Step 8/9 (Regeneration of Oxaloacetate) Fumarate accepts a water molecule, turning into malate, which is then oxidized, producing oxaloacetate one NADH.
fermentation
- Occurs when oxygen is not available
- ATP must be produced by glycolysis
- Final electron acceptor is an organic molecule
Reduces organic molecules in order to regenerate NAD+
fermentation
ethanol fermentation
- occurs in yeast
* CO2, ethanol, and NAD+ are produced
lactic acid fermentation
- occurs in animal cells (especially muscles)
* electrons are transferred from NADH to pyruvate to produce lactic acid
matrix
The inner-mitochondrial space, inside the inner membrane.
cristae
The folds of the inner membrane layer of the mitochondrion, creating many layers.
lactate
Ionized form of lactic acid
alcohol
A reduced organic compound through fermentation.
