Ch. 7 How Cells Harvest Energy Flashcards
What’s an autotroph able to do?
produce own organic molecules through photosynthesis
Where do heterotrophs live?
on organic compounds produced by other organisms
What does cellular respiration extract?
energy from organic molecules
When dehydrogenation occurs, what’re lost electrons accompanied by?
protons
What does H+ stand for?
a hydrogen ion
What does e- stand for?
electron
How many electrons and protons must NAD+ receive to become NADH?
2 electrons and 1 proton
What is the final electron acceptor in aerobic respiration?
oxygen
What’s the final electron acceptor in anaerobic respiration?
inorganic molecules (that are NOT oxygen)
What’s the final electron acceptor in fermentation?
organic molecules
NAD+ is the _____ form whereas NADH is the ______ form.
Oxidized, reduced
What drives endergonic reactions?
ATP
What are the two mechanisms for synthesis?
1) substrate level phosphorylation
2) Oxidative phosphorylation
What are the 4 steps if oxidation of glucose?
1) glycolysis
2) pyruvate oxidation
3) citric acid cycle
4) electron transport chain and chemiosmosis
During glycolysis, how much glucose is converted into 2 pyruvate?
one
What is the net production of glycolysis?
2
What are the products of glycolysis?
2 pyruvate, 2 water, 4 ATP
What is Aerobic respiration?
when oxygen is available as the final electron acceptor and produces a significant amount go ATP
What is fermentation?
when oxygen isn’t available, so organic molecules are the final electron acceptor (pyruvate is reduced to oxidize NADH into NAD+)
What is the energy yield of respiration?
32 ATP per glucose in bacteria
30 ATP per glucose in eukaryotes
What is the electron carrier process (3 steps)?
1) soluble carriers move electrons from one molecule to the next
2) membrane-bound carriers form a redox chain
3) carriers move w/in the membrane
What is a NAD+ molecule made up of?
1) AMP which acts as the core and provides the shape
2) NMP which is readily reduced since its the active part and easily accepts electrons
How does NAD+ become NADH?
When its reduced by accepting 2 electrons and a proton
How is ATP formed in substrate-level phosphorylation?
by transferring a phosphate group directly to ADP
How is ATP formed in oxidative phosphorylation?
by ATP sythnase using energy from a proton (H+) graident; ADP+Pi= ATP; used by eukaryotes and aerobic prokaryotes
Where is the electron transport chain located in eukaryotes and prokaryotes?
1) mitochondrial inner membrane in eukaryotes
2) inter-foldings of plasma membrane in prokaryotes
What’s the electron transport chain do?
releases energy to be converted to potential energy in the form of an electrochemical gradient
What are the 3 major steps to Glycolysis?
1) primary reactions that change glucose into two separate 3-carbon phosphorated molecules (G3P); needs 2 ATP to activate
2) Cleavage in which the G3P go through more reactions
3) Oxidation and ATP formation in which both G3Ps are oxidized and transfer 2 electrons and 2 proton to NAD+ to create NADH and then transferred to ADP to create ATP
What is the end process of Glycolysis yield?
4 ATP (2 per each G3P) minus 2 ATP (activation energy) = 2 ATP net yield
Which came first? ATP breakdown of G3P or the synthesis of G3P from glucose?
ATP breakdown of G3P
When pyruvate oxidized in the mitochondria, what does it produce?
Acetyl-CoA and CO2 which links glycolysis and the reactions of the citric acid cycle in which CoA is recycled to be used again in oxidation of pyruvate
What’s the Citric Acid Cycle (CAC)?
the oxidation go 2-carbon units in the form of acetyl groups bound to CoA from the oxidation go pyruvate or the oxidation of fatty acids
What is the reaction of the CAC?
the conversion of citrate back to oxaloacetate which generates CO2 and transfers electrons and protons to carriers NADH and NAD+
What are the 3 steps in the CAC?
1) 4-carbon oxaloacetate is combined with acetyl = 6-carbon citrate molecules
2) citrate is converted to 5-carbon intermediate and then into a 4-carbon succinate which produces 2 NADH and 1 ATP
3) succinate undergoes 3 reactions and becomes oxaloacetate which produces 1 NADH; 1 FAD gets reduced to FADH2
What are the 9 reactions in the CAC?
1) condensation in which citrate is formed (irreversible)
2 & 3) Isomerization (a -H group and -OH group change positions to create isocitrate)
4) 1st oxidation in which isocitrate becomes alpha ketoglutarate
5) 2nd oxidation where alpha ketoglutarate becomes succinylcholine-CoA
6) substrate level phosphorylation occurs and GDP takes a phosphate to ADP = ATP
7) 3rd oxidation in which succinate becomes fumarate and FAD is reduced to FADH2
8-9) Regeneration of oxaloacetate and fumarate combines with water to make malate which gets oxidized to oxaloacetate and NAD+ reduces to NADH
What is the end result of the CAC?
2 CO2, 1 ATP, 4 pairs of electrons
What’s the first protein to receive electrons in the transport chain?
NADH dehydrogenase
How many proton pumps get activated by NAD+ and FADH2?
NAD+ = 3
FADH2 = 2
What’s chemiosmosis?
formulation of ATP driven by diffusion; coupling of electron transport and ATP synthesis
ATP sythnase is a molecular rotary motor. What are the two sub portions of this and what do they do?
1) F0 = membrane bound complex that allows electrons to move down their concentration gradients
2) F1 = composed of the stalk and a knob (head domain) and is where enzymatic activity occurs
- both drive the rotation go the ATP syhtnase generator
What is the P/O ratio?
the value for the amount of ATP synthesized per oxygen molecule (aka Phosphate-to-oxygen ratio) which yields about 2.5
What enzyme is the control point for glycolysis?
Phosphofructokinase which is inhibited by ATP, citrate, or both
What enzyme is the control point for pyruvate?
Pyruvate dehydrogenase which is inhibited by NADH
Does anaerobic respiration produce more or less ATP than other respiration methods?
less
What did photosynthesis begin as? When it evolved, what did it do?
Began as an an oxygenic process that once evolved, produced free oxygen which allowed the evolution of aerobic respiration to occur
In anaerobic respiration, pyruvate turns into what at the end of glycolysis?
lactic acid; occurs in animals; makes ATP
A single “turn” of CAC yields what?
1 ATP, 3 NADH, 1 FADH2
Where does ethanol fermentation occur?
yeast; makes ATP
What does Alanine convert to?
pyruvate
What does aspartate convert to?
oxaloacetate
What are the 6 steps in the evolution of metabolism?
1) ability to store chemical energy in ATP
2) evolution of glycolysis
3) anoxygenic photosynthesis (using H2S)
4) use of water in photosynthesis (not using H2S -> changes atmosphere of earth)
5) evolution of nitrogen fixation
6) Aerobic respiration evolves
