Topic 11: Cellular Respiration Flashcards
Describe the glycolysis process and TCA cycle
- Glycolysis: sugar splitting
+ 1 glucose molecule takes 2 phosphate groups from ATP to integrate at the 2 ends
+ the new compound is unstable so it splits to make 2 new G3Ps
+ G3Ps are then converted to pyruvate which gives off electron in the process to make NADH and energy as ATP
+ the products are 2 pyruvates, 2 net ATP, and 2 NADH - TCA/Krebs cycle: mainly take away electrons from the glycolysis products
+ pyruvate enters the cycle by losing 1 carbon, making CO2, and becoming Acetyl (2C)
+ Acetyl joins with CoA to become acetyl Coa which enter the cycle
+ Acetyl CoA combines with oxaloacetate (4C) to make citrate (6C) is produced, then converted to alpha-ketoglutarate (5C) to succinyl CoA (4C) to succinate (4C) to fumarate to malate with water added. Back to oxaloacetate.
+ CO2, NADH and FADH2 are produced along the way with the C and H+/e- being released. 1 ATP is also one product.
Describe the electron transport chain and oxidative phosphorylation in mitochondria
- On the inner membrane of the mitochondrion
- NADH and FADH2 donates electrons to proteins integrated in the membrane and the electrons keep going through the transport chain which helps to pump protons into the inter-membrane space.
- The terminal electron acceptor is oxygen which receives electrons to make water.
- The proton gradient drives protons to move back in the matrix via ATP synthase. Protons moving makes energy to catalyze the phosphorylation of ADP by ATP synthase to make ATP. (oxidative phosphorylation)
Compare photosynthetic electron transport and the electron transport chain in mitochondria
- Photophosphorylation in photosynthetic ECT
- NADP is the terminal e- acceptor in photosynthetic ECT
- Oxidative phosphorylation in mitochondrial ECT
- O2 is the terminal e- acceptor in mitochondrial ECT
Describe variations on the basic model of cellular respiration (special proteins in ECT)
In mitochondria in plants:
- Alternative oxidase (AOX):
+ as usual, electrons flow from complex I-IV to pump protons, making proton gradient with O2 being terminal e- acceptor –> energy-conserving cytochrome pathway
+ in mitochondrion of plants, the electrons don’t go to complex III-IV but go through AOX to react with O2.
+ fewer electrons travel in ECT –> smaller proton gradient –> less ATP produced –> non-energy conserving pathway - Uncoupling protein:
+ lets H+ ions passively diffuses through the membrane into the matrix without going through the ATP synthase –> less ATP being produced + wasted energy released as heat
Why do AOX and UCP exist in mitochondria of plants even though they are wasting energy?
These proteins act to control or finetune the process of ATP production to make sure the demand is sufficient, like a safety valve to prevent ECT from being saturated with electrons.
What is the difference in the energy being released in burning and aerobic respiration?
- Burning results in energy being released on 1 go and as heat.
- Aerobic respiration results in energy being released in 4 steps with a controlled fashion and as heat and also energy stored in ATP.
Where do glycolysis, Krebs cyclea and ECT happen in a cell?
- Glycolysis happens in the cytoplasm
- Krebs cycle happens in the mitochondrion matrix
- ECT happens within the inner membrane of mitochondrion
How are mitochondria and chloroplast similar?
- Both have outer and inner membrane
- Have mechanisms to increase surface area:
+ mitochondria: inner membrane fold to make crista
+ chloroplast: thylakoids stack to make grana - Independent existence within cells with ability to make their own proteins from their own DNA
–> suggest endosymbiosis engulfing by early prokaryotic ancestors
What is the use of AOX in some plants? and what is special about it being used in respiration in sacred lotus?
AOX is utilized in some plants to heat plant tissues.
- When temperature decreases, respiration in lotus increases to warm tissues.
- When temperature increases, respiration goes down.
