Cellular Respiration Flashcards
the breakdown of organic molecules can be described as..?
exergonic
fermentation
partial degradation of sugars that occurs without O2
aerobic Respiration
consumes organic molecules and O2 and yields ATP
anaerobic respiration
similar to aerobic respiration but consumes compounds other than O2
Cellular Respiration
includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration
redox reaction
transfer of electrons
oxidation
substance loses electrons
reduction
substance gains electrons
reducing agent
electron donor (substance being oxidized)
if a particular redox rxn. doesn’t transfer electrons it…
changes the electron sharing in covalent bonds
what is oxidized/reduced during cellular respiration
- glucose is oxidized
- oxygen is reduced
dehydrogenase
enzyme used in reduction of NAD+
(NAD+ —> NADH)
- NAD+ is the oxidizing agent (electron acceptor)
stages of cellular respiration
- glycolysis
- citric acid cycle (Kreb’s Cycle)
- oxidative phosphorylation
glycolysis
breaks down glucose into two molecules of pyruvate
citric acid cycle
completes breakdown of glucose
oxidative phosphorylation
accounts for 90% of the ATP generated by cellular respiration
phases of glycolysis
- energy investment phase
- energy payoff phase
substrate-level phsphoylation
accounts for smaller amounts of ATP formed in glycolysis and citric-acid cycle
what accounts for the most energy extracted from food?
following glycolysis and the C.A.C, NADH and FADH2
what do NADH and FADH2 do?
these two electron carriers donate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation
where is the electron transport chain?
in the cristae of the mitochondrion
what makes up the ETC?
proteins which exist in multiprotein complexes
what do the carriers do in the ETC?
alternate reduced and oxidized states as they accept and donate electrons
what do electrons do in the ETC?
electrons drop in free energy as they go down the chain and are finally passed to O2, forming H2O
where are electrons tranferred?
from NADH or FADH2 to the ETC
what are electrons passed through
a number of proteins including cytochromes (each with an iron atom) to O2
does the ETC generate ATP?
no
what is the ETC’s function?
to break the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts
what does electron transfer in the ETC cause?
it causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space
ATP synthase
where channels, which pass H+ through the membrane, are located
what driver the phosphorylation of ATP?
ATP synthase using the exergonic of H+
chemiosmosis
the use of energy in a H+ gradient to drive cellular work
what happens to the H+ stored in the H+ gradient across the membrane?
the H+ stored in a H+ gradient couples redox reaction of the ETC to ATP synthesis
proton-motive force
a term used to refer o the H+ gradient, emphasizing its capacity to do work
sequence of energy flow during cellular respiration
glucose–>NADH–>ETC–>proton-motive force–> ATP
how much ATP is made during cellular respiration?
about 40% of the energy in a glucose molecule is transferred to ATP during cellular respiration, making about 38 ATP
under what condition can glycolysis produce ATP?
aerobic or anaerobic conditions
(with or without O2)
glycolysis in the absence of O2
glycolysis couples with fermentation or anaerobic respiration to produce ATP
describe fermentation
- uses phosphorylation to generate ATP
- consists of glycolysis plus rxn.s that generate NAD+, which can be reused by glycolysis
two common types of fermentation
alcohol fermentation and lactic acid fermentation
alcohol fermentation
pyruvate is converted to ethanol in two steps, with the first releasing CO2
when is alcohol fermentation used?
(by yeast) is used in brewing, winemaking, and breadmaking
lactic acid fermentation
pyruvate is reduced to NADH, forming lactate as an end product, with no release of CO2
when is lactic acid fermentation used?
(by some fungi) to make cheese and yogurt
what do human muscles use?
human muscles use lactic acid fermentation to generate ATP when O2 is scarce
what do fermentation and cellular respiration have in common?
both processes use glycolysis to oxidize glucose and other organic fuels to pyruvate
where do fermentation and cellular respiration differ?
the processes have different final electron acceptors
- Cell. Resp. = O2
- Fermentation = org. molecule (pyruvate or acetalaldehyde)
obligate anaerobes
carry out fermentation or anaerobic respiration and cannot survive in the presence of O2
facultative anaerobes
