Quiz 6 - Glycolysis, Citric Acid Cycle, Oxidative Phosphorylation Flashcards
Cellular respiration
Cellular pathways that synthesize ATP by moving electrons from glucose to O2.
Gives off CO2, requires O2, has both anaerobic and aerobic processes
Glycolysis
Anaerobic ATP and electron carrier reduction.
NAD+ is electron acceptor, must be maintained
When/where is glycolyis alone the source of energy?
Erythrocytes (lack mitochondria)
Cancer cells
Anaerobic bacteria
Glycolysis preparatory phase
Glucose + Hexokinase + ATP > G6P + phosphohexose isomerase > F6P + Phosphofructokinase-1 > F16BP + Aldolase > G3P + DHaP
Triose phosphate isomerase
Converts Dihydroxyacetone Phosphate into Glyceraldehyde 3 phosphate
Glycolysis Payoff phase
G3P + G3P dehydrogenase + NAD+ > (NADH) 13BPG + Phosphoglycerate Kinase + ADP > (ATP) 3 PG + Phosphoglycerate mutase > 2 PG + Enolase > PEP + pyruvate kinase + ADP > (ATP) Pyruvate
Net balance of glycolysis
2 Pyruvate
2 ATP
2 NADH + H+
Other sources of Glycolysis molecules
Different sugars can be modified to become different steps of glycolysis
Diabetes mellitus types
Type 1 - lack of cells that produce insulin
Type 2 - cellular insensitivity to insulin
How do insulin and glucagon balance cell glucose levels?
Insulin leads to synthesis of glycolytic enzymes, brings glucose into cells
Glucagon increases enzymes that cause gluconeogenesis and glycogen synthesis
Interplay between these processes balances
Possible fates of pyruvate
Aerobic conditions - Conversion into Acetyl-CoA
Anaerobic conditions - conversion into lactate or ethanol via fermentation
Purpose of Fermentation
Regenerates NAD+ in anaerobic conditions to allow glycolysis to continue
Lactate is electron acceptor of NADH
Cori Cycle
Lactate from muscles enters bloodstream, goes to liver, where it is converted to glucose via gluconeogenesis
Pentose phosphate pathway
Lack of NADPH leads to this pathway to create more NADPH and ribose sugars
Ribose sugars
Nucleotides, ATP, FAD, Coenzyme A
NADPH
Necessary for reductive biosynthesis and free radical protection.
Where do steps of respiration occur
Glycolysis - cytoplasm
Pyruvate»_space; Electron transport chain - Mitochondria
How do mitochondria affect apoptosis?
DNA damage, developmental signals, stress and reactive oxygen species lead to disruption of mitochondria membrane, releasing cytochromes and other contents that activate a chain of proteins. Activation of Caspase proteins lead to cell death.
Pyruvate conversion to Acetyl-CoA
Pyruvate + Pyruvate Dehydrogenase Complex + NAD+ > Acetyl-CoA + CO2 + NADH
Citric Acid Cycle net production per turn
3 NADH
2 CO2
1 GTP (ATP)
1 FADH2
Citric acid cycle
OxA + Acetyl-CoA + Citrate Synthase > Citrate + aconitase > Isoscitrate + Isocitrate dehydrogenase > (CO2 + NADH) alpha ketoglutarate + akg dehydrogenase > (CO2 + NADH) Succinyl-CoA + Succinyl-CoA synthase > (GTP) Succinate + succinate dehydrogenase > (FADH2) Fumarate + fumarase > malate + malate dehydrogenase > (NADH) OxA
Synthetic pathway
Different substrates along the pathway can be pulled to create other products like amino acids, nucleic acids, fatty acids, gluconeogenesis, neurotransmitters, hemes
Oxidative Phosphorylation
Occurs in between inner mitochondrial membrane and the matrix. Electrons from glycolysis and citric acid cycle are moved through proteins to phosphorylate ADP (create ATP)
Regulation of Phosphofructokinase-1
Presence of ATP and/or Citrate inhibits PFK-1
Presence of ADP and/or AMP promotes PFK-1
Insulin promotes synthesis of PFK-1
Glucagon inhibits synthesis of PFK-1
Pyruvate dehydrogenase complex
3 cooperative proteins that convert Pyruvate into Acetyl-CoA. Utilizes an internal acyl lipolysine to transfer acetyl group from pyruvate to the CoA
Regulation of citric acid cycle
Allosteric regulation of enzymes. Regulated at most exergonic steps. Presence of ADP promotes, Presence of ATP inhibits
Mass action regulates function - too much product slows, not enough speeds up
Ubiquinone
Coenzyme Q - carries both electrons and protons (QH2)
Cytochromes
Only accepts electrons
Iron-Sulfur proteins
Only accepts electrons, found within complexes
Regulation of Respiratory chain
Allosteric regulation. Too much ATP or NAD+ inhibits
Excess ADP promotes
Reactive Oxygen species formation
Buildup of ubiquinone can cause transfer of electrons onto O2, creating free radicals.
Mitochondria not making ATP due to lack of O2 or ADP, or excess of NADH promotes formation of ROS