Lecture 12-14: Catabolic Pathways Flashcards
Catabolic pathways:
release energy by breaking down complex molecules into simpler compounds
aerobic respiration:
oxygen is consumed as a reactant along with organic fuel
anaerobic respiration:
organic fuel is broken down without oxygen
fermentation:
partial breakdown of organic fuel (sugars) without oxygen
what is the chemical formula for cellular respiration?
C6H12O6 + 6O2 -> 6CO2 + 6H2O + Energy
what kind of respiration is cellular respiration?
aerobic (and anaerobic)
what do catabolic reactions depend on during chemical reactions?
transferring of electrons
the transfer of electrons from one molecule to another is…
redox (always coupled!)
catchphrase for loss or gain of electrons?
LEO goes GER
what is nicotinamide adenine dinucleotide (NAD+)?
electron transporter (shuttle)
-> a coenzyme and oxidizing agent
-> cycles between oxidized (NAD+) and reduced (NADH)
why do electrons move in a step-wise process?
if the transfer was uncontrolled, there would be one big release of energy with lots of heat loss
by using small releases of energy at each step, more ATP can be created
two ways ATP is made:
substrate level phosphorylation
oxidative phosphorylation
where does glycolysis/citric acid cycle/OxPhos happen in prokaryotes?
glycolysis/krebs: cytosol
oxphos: plasma membrane
what does glycolysis mean in a nutshell?
sugar-splitting
2 phases of glycolysis:
energy investment (cell “spends” ATP)
energy payoff (ATP is produced via substrate-level phosphorylation)
what do you gain overall from glycolysis?
2 ATP and 2 NADH
where is the pyruvate produced in glycolysis taken?
mitochondrion
what is pyruvate converted into?
acetyl CoA
what does the citric acid cycle produce per cycle?
1 ATP molecule via substrate-level phosphorylation, 2 total because two pyruvate start off the cycle
total of ATP created per glucose molecule in glycolysis and krebs cycle?
4 ATP (2+2)
collection of protein complexes within the inner membrane of the mitochondrion:
electron transport chain
what does ATP synthase make?
ATP from ADP and inorganic P using oxidative phosphorylation
what is chemiosmosis?
an energy-coupling mechanism
-> uses energy stored in the form of H+ gradient across the membrane to drive cellular work
anaerobic respiration:
respiration in which the final electron acceptor is not oxygen
fermentation:
does not have an ETC or oxygen as the final electron acceptor
what does fermentation recycle?
NAD+ from NADH during glycolysis
two types of fermentation:
alcohol fermentation and lactic acid fermentation
alcohol fermentation:
pyruvate is converted to ethanol (aka ethyl alcohol)
lactic acid fermentation:
pyruvate is reduced directly by NADH to form lactic acid, no release of CO2
obligate anaerobes:
organisms that only carry out fermentation or anaerobic respiration
facultative anaerobes:
organisms can utilise both fermentation and cellular respiration to make enough ATP
