Lecture 7 Flashcards
What is the difference between substrate level phosphorylation and oxidative phosphorylation?
Substrate level phosphorylation directly transfers of phosphate group from a high energy molecule, two ATP, producing ATP. Oxidative phosphorylation involves the electron transport chain and electrons are passed through a series of protein complexes to generate a concentration gradient across the membrane, driving synthesis of ATP through ATP synthase.
Why is Lactic Acid NOT produced in the presence of oxygen? Where does the oxidation of the reduced coenzymes occur?
Lactic acid is not produced in the presence of oxygen because cells use aerobic respiration when oxygen is present and aerobic, respiration does not require the conversion of pyruvate into lactic acid. The oxidation of the reduced enzymes occur occurs in the mitochondria.
What are the products of glycolysis? Which are shuttled (transported) into the mitochondria? Once in the mitochondria, how is pyruvate assisted into the Krebs Cycle? (hint: what organic “helper” can assist the enzymatic breakdown of the carbon skeleton? What are the products of this incorporation of pyruvate into the mitochondrion (what are the products of the “prep steps”?) What happens to each of the products?
What two sets of chemical reactions occur within the mitochondria in the process of ATP production? Which one uses substrate level phosphorylation and which one uses oxidative phosphorylation?
Within the mitochondria, Krebs cycle and electron transport chain. Krebs cycle use a substrate level phosphorylation and electron transport chain uses oxidative phosphorylation.
What are the products of the Krebs Cycle (per pyruvate)? Following the transport of pyruvate into the mitochondria and the movement into and through one “turn” of the Krebs Cycle, how many CO2 molecules are produced? When the Krebs cycle is complete, are any bonds from the original glucose remaining from which to harvest energy? Where is the remaining energy located that is needed to power the remaining 26 – 28 ATPs?
1 ATP, 3 NADH + H+, 1 FADH2, and 2CO2. The energy comes from electrons carried by NADH + H+ and FADH2, which will then be used in the electron transport chain to generate the remaining 26 to 28 ATP.
What is the functional significance of the Krebs Cycle – is it to make ATP or is it to make something else?
The functional significance of the Krebs cycle is to produce 1 ATP which then generates NADH and FADH2 in order to produce high energy electrons.
What are the four main functions of the electron transport & oxidative phosphorylation processes?
Redox (oxidize NADH and FADH2 to transport electrons to adjacent carriers) , proton pump (active transport of hydrogen from the matrix into the inner mitochondrial space generating a hydrogen concentration gradient) , disposal of electrons (reduce oxygen into water) , and produce ATP.
What purpose do the reduced coenzymes of NADH and FADH2 have in the electron transport chain? (What energy storing activity occurs because of the transfer of these electrons?)
What is the ultimate fate of the electrons (which originally came from the glucose) in the electron transport chain? What is the FINAL electron acceptor of the electrons and what results from the process?
It gets passed through the electron transport chain via H+ pumps to generate a H+ gradient. The final electron acceptor is ATP synthase which ultimately generates 26-28 more ATP.
How is the hydrogen concentration gradient formed? What is the concentration gradient used for?
It is formed by H+ pumps in the electron transport system pumping hydrogens up its concentration gradient to create a higher H+ ion concentration gradient. The concentration gradient is then used by ATP synthase to generate ATP. H+ ions enter the rotor to turn it, which needs a concentration gradient.
What are the respiratory assemblies? What are there two parts and what is the primary function of each?
It is a 2 part protein complex that uses a H+ channel for facilitated diffusion and ATP synthase as the enzyme. ATP synthase has binding sides for ADP and inorganic phosphate to generate ATP.
Cyanide is a poisonous gas that results in rapid death. Cyanide functions by binding to and adversely affecting the last electron transport in the chain so that the electrons can not be removed. Using your knowledge of the ETC, explain why cyanide results in death.
It blocks the transfer of electrons and blocks ATP production so cells are deprived of the energy that they need to function.
How much ATP is produced in glycolysis, How much ATP is produced in Krebs? How much ATP is produced by the oxidative phosphorylation at the ETC?
2, 2. And then 30-32 depending on if FADH2 or NADH is utilized in ETC.
The theoretical ATP yield for the complete oxidation of glucose is 36 or 38 ATP. Why is the actual ATP yield slightly less (30 or 32ATP)? (Hint: What is the difference between mitochondrial ATP yield and cytoplasmic ATP?)
Why is the overall mitochondrial ATP production listed as either 30 or 32 (or theoretical as 36 or 38)? Hint: What is the difference between the NADH oxidation of FADH2 by the electron transport chain?)
