ch.7 cellular respiration Flashcards
how do autotrophs obtain energy?
they capture energy and build organic molecules through photosynthesis
how do heterotrophs obtain energy?
they use organic molecules for energy and to build new organic molecules
how do all organisms extract energy from organic molecules?
cellular respirations
what type of reaction is cellular respiration?
redox reaction
How does NAD+ become NADH?
by accepting two electrons and one proton
what is the goal of cellular respiration?
to generate a lot of atp
what is aerobic cellular respiration?
cellular respiration where the final electron acceptor is oxygen
what is anaerobic cellular respiration?
cellular respiration where the final electron acceptor is an inorganic molecule
what is fermentative cellular respiration?
cellular respiration where the final electron acceptor is an organic molecule (lactate or ethanol)
What happens to electrons during respiration?
they are shuffles via electron carriers to a final electron acceptor
what is another word for aerobic respiration?
exergonic
the change of gibbs free energy = ….
the change in enthalpy - (temp) (change in entropy)
what is enthalpy?
the sum of the internal energy and the product of its pressure and volume
what is the equation of cellular respiration?
C6H12O6 + 6O2 —> 6CO2 + 6H2O
what is delta G?
the change in free energy
what is the DG for cellular respiration?
- 686kcal/mol of glucose
what is the main outcome of cell resp?
transfer of energy in making atp
what happens to energy in cell resp?
it is released from redox reactions as electrons drop from high to lower energy levels
What do electron transport chains do?
shuttle electrons via electron carriers
what are the two ways that cells make ATP from ADP and Pi?
substrate-level phosphorylation and oxidative phosphorylation
what is substrate-level phosphorylation?
transferring a phosphate directly from another molecule to ADP
what is oxidative phosphorylation?
use of a membrane bound atp synthase enzyme and a proton gradient
what is another name for oxidative phosphorylation?
chemiosmosis
what does the enzyme do in substrate-level phosphorylation?
directly transfers from the substrate(PEP) to ADP
what is the function of ATP synthase?
uses a proton gradient(H+) to produce atp from adp and pi
what are the five steps of glucose oxidation?
1.Glycolysis (cytosol)
In mitochondria
2. pyruvate oxidation
3. Krebs cycle
4. Electron Transport Chain
5. Chemiosmosis (ATP synthase and H+ gradient)
what does glycolysis do?
converts glucose to 2 pyruvates
what is glycolysis?
-a 10-step biochemical pathway that occurs in the cytoplasm
how are 2 ATP molecules produced in glycolysis?
substrate level phosphorylation and 2 NADH by reduction of NAD+
what does each NADH produced in glycolysis translate to?
3 atps being made by atp synthase by the electron transport chain
what must happen for glycolysis to continue?
NADH must be regenerated to NAD+ by either fermentation or aerobic respiration
what is aerobic respiration?
uses O2 as the final electron/H+ acceptor forming metabolic water
what does aerobic respiration form?
metabolic water
what is fermentation?
uses an organic molecule as the final electron/H+ acceptor forming a reduced organic molecule. (ETOH or Lactate)
what does fermentation produce?
a reduced organic molecule (EOTC or Lactate)
what does the fate of private depend on?
O2 availability
what is the fate of private when O2 is present?
pyruvate is oxidized in the matrix of the mitochondria to acetyl-CoA, which then enters the Krebs cycle.
when O2 is present, where does pyruvate oxidation occur in eukaryotes?
in the mitochondrial matrix
what is the fate of pyruvate without O2?
pyruvate remains in the cytosol and is reduced in order to oxidize NADH back to NAD+
what catalyzes pyruvate oxidation in the mitochondria?
pyruvate dehydrogenase
when O2 is present, where does pyruvate oxidation occur in prokaryotes?
in the cell membrane
what are the products of pyruvate oxidation?
1 CO2
-1 NADH
-1 acetyl-CoA
(2 carbons from pyruvate attached to coenzyme A)
what composes acetyl-CoA?
2 carbons from pyruvate attached to coenzyme A
where does acetyl-CoA go after pyruvate oxidation?
the krebs cycle
what is the krebs cycle?
a nine step biochemical pathway that brings in acetyl-CoA
what is the purpose of biological cycles?
to provide a carbon-based molecular scaffold upon which other molecules can be attached, then degraded or built, with the end result being the return of the original scaffold molecule
What comes out of the Krebs Cycle?
-release 2 molecules of CO2
-reduce 3 NAD+ to 3 NADH
-reduce 1 FAD to FADH2
-produce 1 ATP from ADP + Pi via substrate-level phosphorylation
-regenerate the scaffold oxaloacetate so that cycle can continue
what are the products from glucose after glycolysis, pyruvate oxidation, and the Krebs cycle?
- 6 CO2
- 4 ATP
- 10 NADH
- 2 FADH2
where do the electron carriers go after the krebs cycle?
the electron transport chain
what is the ETC?
a series of electron carriers embedded in the mitochondrial inner membrane.
where are electrons transferred from to the carriers in the etc?
NADH and FADH2
what happens as electrons are transferred among carriers?
some energy is lost
what is the “lost” energy in the ETC used for?
to pump protons (H+) across the membrane from the matrix to the inner membrane space
what is established during the ETC?
a proton gradient
in the ETC, what attracts the protons in the matrix from the intermembrane space?
the high negative charge
what is the purpose of atp synthase?
produce atp from adp and pi
what is the theoretical energy yield per glucose for bacteria?
38 atp
what is the theoretical energy yield per glucose for eukaryotes?
36 ATP
what is the actual energy yield per glucose in eukaryotes?
30 atp
why is there a lesser actual energy yield than theoretical energy yield?
“leaky” inner membrane and use of the proton gradient for purposes other than ATP synthesis
what are the two forms of oxidation with out O2?
anaerobic respiration and fermentation
what does anaerobic respiration uses as the final electron/H+ acceptor?
inorganic molecules other than O2
what does fermentation uses as the final electron/H+ acceptor?
organic molecules
anaerobic methanogens use ____ to reduce ____ to _____
NADH, CO2, CH4 (methane)
anaerobic sulfur bacteria use ____ to reduce _____ to ________.
NADH, SO4 (inorganic sulfur), H2S (hydrogen sulfide)
what does ethanol fermentation occur in?
yeast
what does fermentation do?
reduces organic molecules in order to regenerate NAD+
what happens in ethanol fermentation?
CO2 is released from pyruvate forming acetaldehyde which is then reduced by NADH to ethanol and NAD+
where does lactic acid fermentation occur?
in animal cells, especially muscles
what happens in lactic acid fermentation?
NADH reduces pyruvate to lactic acid and NAD+
What proteins and fats are catabolized during glycolysis?
carbohydrates, some amino acids, and glycerol
What proteins and fats are catabolized during pyruvate oxidation?
fatty acids and some amino acids
What proteins and fats are catabolized during the citric acid cycle?
some amino acids
what happens to fats when they are catabolized?
they are broken down into fatty acids and glycerol
what happens to fatty acids that come from catabolized fats?
they are concerted into acetyl groups
the respiration of a 6-carbon fatty acid yields how much more (%) than glucose?
20%
what do ATP and citrate allosterically inhibit?
phosphofructokinase (enzyme)
what does ANDH inhibit?
pyruvate dehydrogenase (enzyme)
what enzyme does ATP inhibit?
citrate sythetase
what is a hypothetical timeline for the evolution of metabolism?
- ability to store chemical energy in ATP
- evolution of glycolysis
- anaerobic photosynthesis (using H2S)
- use of H2O in photosynthesis (not H2S)
- evolution of nitrogen fixation
- aerobic respiration evolved most recentl
