Cellular respiration Flashcards
What is a difference between oxidative phosphorylation and substrate level phosphorylation?
Oxidative phosphorylation relies on the action of a large multiprotein complex that spans the inner mitochondrial inner membrane called ATP synthase. Substrate-level phosphorylation involves the transfer of a phosphate group from a high energy substrate molecule to ADP.
When does substrate-level phosphorylation occurs?
It occurs during glycolysis and citric acid cycle.
When does oxidative phosphorylation occur?
During chemiosmosis.
What is chemiosmosis?
It is the harnessing of the proton motor force generated by the proton gradient (differences in concentration of H+ and voltage across the inner membrane.
Explains how the ATP synthase produces ATP.
The proton motive force propels H+ through the channels of the enzyme down their concentration gradient and into the matrix. Binding of individual proton to sites in the headpiece causes it to rotate, which catalyzes the formation of ATP from ADP + Pi.
What is an active transport pump?
It is an ATP synthase that is working in reverse. It uses the free energy released by the hydrolysis of ATP to pump ions against their gradient.
What is fundamental to all forms of life and developed early in the evolution of it?
Chemiosmosis, harnessing the potential energy present in a proton gradient to synthesize ATP. ATP synthase complexes found in the thylakoid membrane of chloroplasts and the plasma membrane of many bacteria and archae are similar.
What is the purpose of the electron transport system?
The ETS generate a proton gradient.
ATP is a product of what process?
ATP is a product of chemiosmosis, which consumes the proton gradient generated by ETS.
Explain a fundamental concept linked to ETS and chemiosmosis.
ETS and chemiosmotic generation of ATP are separate and distinct processes and they are not always coupled. It is possible to have high rates of electron transport thus oxygen consumption with no production of ATP with mechanisms that involve uncoupler that provide an alternative route for protons to flow back across the membrane.
What is a proton motive force?
It is the stored energy that contributes to ATP synthesis and to the cotransport of substances to and from mitochondria.
What is important to hibernating animals or newborn infants?
Uncoupling proteins, localized in the inner membrane of mitochondria, form channels through which proton can freely flow, the energy released during ET is lost as heat, this regulates temperature.
How many ATP are produced by the oxidation of NADH, FADH2 during the ETS?
respectively, 3, 2.
Give one reason why the theoretical yield 38 ATP in bacteria, but 36 in eukaryotic cells?
In eukaryotic cells, the energy cost of transporting NADH generated by glycolysis across the mitochondria membrane. The active transport system needed to transport the electrons associated with NADH consumes 1 ATP for each molecule of NADH transported. 2NADH are transported which brings the loss of 2 ATP.
Why are energy transformation not a 100% efficient?
Some of the energy is used to increase the entropy of the surroundings.
