respiration SLOP Flashcards
State 5 processes that ATP is used in
Active transport, DNA replication, cell division, endocytosis and exocytosis, protein synthesis, movement of bacterial flagella, phosphorylation of glucose in glycolysis
Describe the structure of ATP
Ribose (pentose) sugar, 3 phosphate groups (phosphoester bond attaches ribose to first phosphate; phosphoanhydride attaches adjacent phosphates), adenine base
State the name of two processes used to produce ATP in aerobic respiration
Substrate-level phosphorylation and oxidative phosphorylation
State all the stages of aerobic respiration in which ATP is produced
Glycolysis, Krebs cycle, oxidative phosphorylation
Describe how energy is released from ATP
ATP is hydrolysed to ADP, releasing an inorganic phosphate molecule
State the location of glycolysis
Cytoplasm
Describe how glucose is phosphorylated in glycolysis
2 x ATP molecules are broken down and their phosphate groups added to glucose to form hexose bisphosphate
Describe what happens to hexose bisphosphate in glycolysis
It splits into 2 x triose phosphate molecules
Describe how pyruvate is produced in glycolysis from triose phosphate
TP oxidised and H atom added to NAD to produce NADH; 2 x Pi group removed from TP and added to 2 x ADP molecules to form 2 x ATP
State the yield of ATP, NADH and pyruvate in glycolysis per glucose molecule
4 x ATP produced (net 2); 2 x NADH; 2 x pyruvate
Describe the process by which ATP is produced in glycolysis
Substrate-level phosphorylation - enzyme with 2 active sites (pyruvate kinase) takes Pi off phosphorylated compound (TBP) and adds them directly to ADP to make ATP
Describe how pyruvate and NADH reach the mitochondrion
Mitochondrial shunt mechanism - actively transported into mitochondrion
glycolysis involves oxidation despite it being an anaerobic reaction
Hydrogen atoms are being removed from TBP
Describe how the inner mitochondrial membrane is adapted for oxidative phosphorylation
Folded into cristae to provide a larger SA for electron carriers, ATP synthase enzymes, NADH dehydrogenase enzymes
State 3 things found in the mitochondrial matrix
Mitochondrial DNA, 70s ribosomes, enzymes for link reaction and Krebs cycle
Explain how the proton gradient is maintained in the intermembrane space
Phospholipid bilayer impermeable to protons (charged particles); they must pass through a hydrophilic channel protein or be pumped by active transport through a carrier protein
Suggest why the synaptic knobs of neurones contain many mitochondria
They need to synthesise many molecules of neurotransmitter and export them, via exocytosis, into the synaptic cleft. The mitochondria supply the energy needed to do this.
How are mitochondria replicated?
Divide by binary fission
Which stages of respiration take place in the mitochondrial matrix?
Link reaction and Krebs cycle
In what ways is the structure of the mitochondrion similar to that of a chloroplast?
For example, has envelope; folded inner membrane to give large surface area; ATP synthase enzymes and proton channels; electron transport chains; matrix; both have prokaryote-type ribosomes; both have loops of DNA.
In what ways is the structure of the mitochondrion different from that of a chloroplast?
For example, chloroplasts have chlorophyll; coenzymes in chloroplasts are NADP, in mitochondria NAD and FAD; different enzymes; chloroplast usually a bit larger, but both in region of 2–10 μm
Define the terms decarboxylation and dehydrogenation
Decarboxylation - removal of a CO2 molecule; dehydrogenation - removal of H atom(s)
Describe what happens to pyruvate in the Link reaction
Pyruvate is decarboxylated and dehydrogenated by pyruvate decarboxylase enzyme –> this produces carbon dioxide, reduced NAD and acetate. The acetate (acetyl group) is added to coenzyme A to form Acetyl CoA.
State the yield of ATP, NADH, acetate and CO2 in the Link reaction per glucose molecules
0 ATP produced, 2 x NADH, 2 x CO2, 2 x acetate
How is the acetyl group carried to the Krebs cycle?
It is added to coenzyme A to form acetyl CoA
How many ATP molecules are produced PER TURN of the Krebs cycle, and by what process?
1; substrate-level phosphorylation
Describe how the acetyl group is used in the Krebs cycle
It is added to oxaloacetate (4C) to become citrate (6C)
How many reduced NAD molecules are produced per glucose molecule in the Krebs
6
How many reduced FAD molecules are produced per glucose molecule in the Krebs cycle
2
How many CO2 molecules are produced PER TURN of the Krebs cycle?
2
Which is the only stage of aerobic respiration that does NOT produce ATP
link reaction
Define chemiosmosis
The flow of protons down their electrochemical gradient, through channels associated with ATP synthase
Describe the roles of NADH and FADH in oxidative phosphorylation
They release their H atoms, which split into protons and electrons. The protons are pumped across the inner mitochondrial membrane, the electrons enter the electron transport chain
State the names of three enzymes found in the inner mitochondrial membrane
ATP synthase, NADH dehydrogenase, FADH dehydrogenase
Explain why oxygen is described as the final electron acceptor in aerobic respiration
It accepts electrons that are released from the last membrane-embedded electron carrier.
State the name of the final electron acceptor in oxidative phosphorylation
oxygen
Explain why the pH measured within the intermembrane space of mitochondria, is lower than that of both the mitochondrial matrix and the cytoplasm
The accumulation/high concentration of protons lowers the pH.
State the process by which animals and plants respire anaerobically
Animals - lactate fermentation; plants - ethanol fermentation
Describe the ethanol fermentation pathway
Pyruvate is decarboxylated (pyruvate decarboxylase) to form ethanal; ethanal is reduced (ethanol dehydrogenase) to ethanol using H atoms from NADH. NAD is therefore free to accept more H atoms allowing glycolysis to continue
Describe the lactate fermentation pathway
Pyruvate is reduced (gains H atoms from NADH) (catalysed by lactate dehydrogenase) to form lactate, freeing up NAD to accept more H atoms in glycolysis
Describe the fate of lactate
Carried to the liver where it is reconverted to pyruvate (which can then enter Link reaction) OR converted back into glucose/glycogen
How many ATP molecules per glucose are produced in both lactate and ethanol fermentation?
4 (net 2)
State the equation for RQ
CO2 produced/O2 absorbed
Explain why lipids produce more energy per g than carbohydrates
More C - H bonds = more H atoms, = more protons can be formed, = steeper proton gradient, therefore more ATP via oxidative phosphorylation
State the RQ values of proteins, carbohydrates and lipids
Proteins - 0.8; lipids - 0.7; carbohydrates - 1
What is the purpose of sodium hydroxide in respirometer tubes?
Absorbs CO2 produced
