Living cells require what from outside sources?
Energy flows into an ecosystem as __________ and leaves as _____.
Photosynthesis generates O2 and organic molecules, which are used in what?
Cells use what stored in organic molecules to regenerate ATP, which powers work?
fermentation, aerobic respiration, anaerobic respiration
The three ATP producing pathways are
A partial degradation of sugars that occurs without O2
Consumes organic molecules and O2 and yields ATP
Similar to aerobic respiration but consumes compounds other than O2
What includes both aerobic respiration and anaerobic respiration but is often used to refer to aerobic respiration?
Although carbohydrates, fats, and proteins are all consumed as fuel, it is helpful to trace cellular respiration with what?
C6H12O6+6O2 = 6CO2+6H2O+Energy (ATP+heat)
Equation for respiration
The transfer of electrons during chemical reactions releases energy stored in what?
The energy released in organic molecules is ultimately used to do what?
oxidation-reduction (redox reactions)
Chemical reactions that transfer electrons between reactants are called what?
A substance loses electrons
a substance gains electrons
The electron donor is called what?
The electron receptor is called what?
Some redox reactions do not transfer electrons but change the electron sharing in what?
During what is fuel (such as glucose) oxidized and O2 is reduced?
NAD+ (a coenzyme)
Electrons from organic compounds are usually first transferred to what?
As an _______ ________, NAD+ functions as an oxidizing agent during cellular respiration.
Each ______ represents stored energy that is tapped to synthesize ATP.
electron transport system
NADH passes the electron to what?
series of steps
Unlike an uncontrolled reaction, the electron transport chain passes electrons in what instead of one explosive reaction?
O2 pulls electrons down the chain in what kind of tumble?
The energy yielded is used to regenerate what?
Aerobic respiration: The main pathway for energy release is from carbohydrate to ATP; What serves as the ultimate hydrogen acceptor?
C6H12O6+6O2+H2O = 6CO2+7H2O+36ATP
Formula for Aerobic respiration
What breaks down glucose into two molecules of pyruvate (PYR)?
What oxidizes PYR to Acetyl-Coenzymes A (AA)?
Completes the breakdown of glucose
Electron Transport System (Oxidative Phosphorylation)
Accounts for most of the ATP synthesis
The process that generates most of the ATP is called what because it is powered by redox reactions?
Oxidative phosphorylation accounts for what percentage of the ATP generated by cellular respiration?
A smaller amount of ATP is formed in glycolysis and the citric acid cycle (Krebs cycle) by what?
For each molecule of glucose degraded to CO2 and water by respiration, the cell makes up to how many molecules of ATP?
Glycolysis ("splitting of sugar") breaks down glucose into two molecules of what?
Where does glycolysis occur?
energy investment phase, energy payoff phase
The two major phases of glycolysis
In the presence of O2, pyruvate enters the what (in eukaryotic cells) where the oxidation of glucose is completed?
acetyl coenzyme A
Before the Krebs cycle can begin, pyruvate must be converted to what, which links glycolysis to the citric acid cycle?
Completes the break down of pyruvate to CO2
The cycle oxidizes what derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH^2 per turn?
Following glycolysis and the citric acid cycle, NADH and FADH^2 account for most of the what extracted from food?
electron transport chain
NADH and FADH^2, both electron carriers, donate electrons to what, which powers ATP synthesis via oxidative phosphorylation?
electron transport chain
Is in the inner membrane (cristae) of the mitochondria
Most of the chain's components are what, which exist in multiprotein complexes?
reduced and oxidized
The carriers alternate ________ and ________ states as they accept and donate electrons.
Electrons drop in what as they go down the chain and are finally passed to O2, forming H2O?
What are transferred from NADH or FADH^2 to the electron transport chain?
Electrons are passed through a number of proteins including what to O2?
The electron transport chain does not generate this directly.
The electron transport chain breaks the large what from food to O2 into smaller steps that release energy in manageable amounts?
What in the electron transport chain causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space?
H+ moves back across the membrane, passing through the proton called what?
ATP synthase uses what of H+ to drive phosphorylation of ATP?
The use of energy in a H+ gradient to drive cellular work is an example of what?
The energy stored in what across a membrane couples the redox reactions of the electron transport chain to ATP synthesis?
The H+ gradient is referred to as what, emphasizing its capacity to do work?
About what percentage of the energy in glucose molecule is transferred to ATP during cellular respiration, making about 32 ATP?
Normally, for every NADH processed by the electron transport system, three ATP are formed; FADH^2 yields two ATP
NADH cannot enter the mitochondrion and must transfer its electrons
skeletal, brain, and most cells
In these places, electrons are transferred to FAD and thus yield two ATP (for a total yield of thirty-six)
liver, heart, and kidney cells
In these places, NAD+ accepts the electrons to yield three ATP; because two NADH are produced per glucose, total yield is 38 ATP.
Most cellular respiration requires what to produce ATP?
electron transport chain
Without O2, what will cease to operate?
final electron acceptor
In the case that there is no O2, anaerobic respiration uses an electron transport chain with what other than O2, for example sulfate?
uses substrate-level phosphorylation instead of an electron transport chain to generate ATP
Consists of glycolysis plus reactions that regenerate NAD+, which can be reused by glycolysis
alcohol fermentation and lactic acid fermentation
Two common types of fermentation
Pyruvate is converted to ethanol in two steps, with the first releasing CO2
Alcohol fermentation by what is used in brewing, winemaking, and baking
lactic acid fermentation
Pyruvate is reduced to NADH, forming lactate as an end product, with no release of CO2
fungi and bacteria
Lactic acid fermentation by some what is used to make cheese and yogurt
human muscle cells
What in humans use lactic acid fermentation to generate ATP when O2 is scarce?
Fermentation, aerobic respiration, and anaerobic respiration all use what to oxidize glucose and harvest chemical energy of food?
Aerobic Respiration: The main pathway for energy release from carbohydrate to ATP; what serves as the ultimate hydrogen acceptor?
Anaerobic respiration: The release of lesser amounts of energy for transfer to a small number of ATP; what other than oxygen serves as the ultimate hydrogen acceptor?
Fermentation: Release of the least amount of energy for transfer to a smallest number of ATP; usually what serves as the ultimate hydrogen acceptor?
catabolic and anabolic
Glycolysis and the citric acid cycle are major intersections to various _________ and ________ pathways.
Funnel electrons from many kinds of organic molecules into cellular respiration
converts sunlight energy to sugar
converts sugar to ATP
Takes place in both photosynthesis and respiration