BIOL2107H Chapter 8: Cellular Respiration
glycolysis, pyruvate oxidation / the citric acid cycle, and oxidative phosphorylation
3 main metabolic stages of harvesting energy from glucose by cellular respiration
directly from food, glycolysis, the citric acid cycle
small molecules used for biosynthesis can come ____________, from _____________, or from____________.
1 ATP, 3 NADH, 1 FADH2, and 2CO2
what are the products of the citric acid cycle
energy investment phase and the energy payoff phase
what are the two major phases of glycolysis
they must be digested to their constituent amino acids with their amino groups removed
what must happen for proteins to be used for fuel
a pyruvate dehydrogenase enzyme oxidizes pyruvates carboxyl group which is released as CO2, reduces NAD+ to NADH by further oxidizing the remaining 2 carbon fragment, and combines the remaining 2-carbon fragment and coenzyme A to form acetyl CoA. occurs in mitochondrial matrix
what occurs between glycolysis and the citric acid cycle and where
the reduced form of nicotinamide adenine dinucleotide that temporarily stores electrons during cellular respiration. acts as an electron donor to the electron transport chain
NADH
top, higher; bottom, lower
NADH shuttles electrons to the _______, ___________-energy end of the chain. at the _____________, ____________-energy end, O2 captures these electrons along with hydrogen nucleii and forms water
2,2, abt 26 or 28, abt 30 or 32
____ atp made in glycolysis, _____ made in citric acid cycle, and about ________ made in oxidative phosphorylation, for a total of ______________ atp
4,2,2
___________ molecules of ATP are made in glycolysis and __________ are used for a NET amount of ____________ ATP
organic; hydrogen; high energy electrons
_______________ molecules with an abundance of _______________ are excellent fuels because they're excellent sources of _________________
oxidative phosphorylation; substrate-level phosphorylation
_________________ accounts for almost 90% of all ATP generated by respiration. a smaller amount of ATP is formed in the other stages of respiration, called _____________________________.
used in 3rd step of glycolysis, its known as the "pacemaker" of respiration. its allosterically regulated; feedback inhibition occurs when too much ATP is created. the ATP binds to the enzyme and inhibits further production until its time to make more again
explain the importance of the phosphofructokinase enzyme
redox reaction
a chemical reaction involving the complete or partial transfer of one or more electrons from one reactant to another
twice as much
a gram of fat oxidized by respiration can produce ___________ ATP as a gram of carbohydrate or protein
the sugar glucose
although carbs, fats, and proteins are all consumed as fuel, its helpful to trace respiration with ____________
converted by enzymes to intermediates of glycolysis and the citric acid cycle
amino acids present in excess are
chemiosmosis
an energy-coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work, such as the synthesis of ATP
cytochromes
an iron-containing protein that is a component of electron transport chains in the mitochondria and chloroplasts of eukaryotic cells and the plasma membranes of prokaryotic cells
dehydrogenase
anytime you see a __________ enzyme working, electron transfer is going on
2 at step 7 and 2 at step 10
at what step(s) does substrate level phosphorylation occur in glycolysis
oxygen
because ___________ is so electronegative, its one of the most powerful of all oxidizing agents
breaking down complex molecules/oxidizing organic fuels
catabolic pathways yield energy by
a series of steps; catalyzed by an enzyme
cellular respiration oxidizes glucose in _____________, each one _____________
citric acid
citrate is the ionized form of
anaerobic respiration
consumes organic molecules and compounds OTHER than O2 to produce ATP
the fuel (such as glucose); O2
during cellular respiration, __________is oxidized and ___________ is reduced
reduced and oxidized
during electron transport, electron carriers go between _________ and _____________----states
stored energy
each NADH molecule formed during respiration represents
exergonic, negative
electron transfer from NADH to oxygen is a ____________ reaction with a ___________ free energy change
NO
electron transport chain generates ______________ ATP directly
drop in free energy; O2; H20
electrons _______________ as they go down the electron transport chain and are finally passed to ______ to make _______
very little
electrons lose _________ of their potential energy when they are transferred from glucose to NAD+
H;O; lower energy state
energy is released as the electrons of __________ are transferred to ___________, at a _____________--
a series of rxns that splits glucose into two pyruvate molecules. occurs in the cytosol.
explain glycolysis
an electron loses potential energy when it shifts from a less electronegative atom toward a more electronegative one, so a redox reaction that moves electrons closer to more electronegative atoms can release chem energy
explain how a redox reaction can release chem energy that can be put to work
some redox reactions just change the degree of electron sharing in covalent bonds. ex) combustion of methane: covalent electrons in methane are shared equally bc H and C have nearly same electronegativity. but when methane reacts with oxygen, electrons are shared less equally between the carbon atom and its new covalent partners, oxygen, which r very electronegative. the O's in the O2 reactant share their electrons equally, but when O reacts with H to form H2O, the electrons spend more time near the oxygen, so O has in effect gained electrons and been reduced.
explain how some redox reactions dont have to involve the complete transfer of electrons from one substance to another
energy flows into an ecosystem as sunlight and exits as heat, and the chemical elements essential to life are recycled. sunlight is used in photosynthesis to create oxygen and organic molecules, which are used by mitochondria as fuel for cellular respiration in eukaryotes. respiration breaks this fuel down, using oxygen and generating ATP (giving off heat energy when used). the CO2 and H2O produced by respiration is then used in photosynthesis.
explain the energy cycle
this is where the electron transport chain accepts electrons from NADH generated from the first two stages and passes these electrons down the chain. at the end of the chain, electrons are combined with molecular oxygen and hydrogen ions, forming water. the energy released at each step of the chain is stored in a form the mitochondrion can use to make ATP from ADP.
explain the general idea behind oxidative phosphorylaton
pyruvate oxidation occurs when, in eukaryotes, pyruvate enters the mitochondrion and is oxidized to a compound called acetyl CoA. acetyl CoA then enters the citric acid cycle, where it is further oxidized to CO2.
explain the general idea behind pyruvate oxidation and the citric acid cycle
fuel source such as glucose --> NADH --> electron transport chain --> oxygen
explain the general route of electrons during cellular respiration
glycerol; fatty acids; glycolysis; enter the citric acid cycle as acetyl CoA
fats are digested to ____________ and _____________. the former is converted to an intermediate of _____________, and the latter is broken down to 2 carbon fragments that _______________
NADH; FADH2
following glycolysis and the citric acid cycle, ______ and _______ account for most of the energy taken from our food
32
for each molecule of glucose degraded to CO2 and H2O, _________ molecules of ATP are made on avg (varies by cell type and other factors)
convert some kinds of molecules to others as we need it
glycolysis and the citric acid cycle function as metabolic interchanges that enable our cells to
carbohydrates; catabolism; starch; glycogen; several disachharides; glucose
glycolysis can accept a wide range of ___________ for ___________, including ______,_______, and _______. they are hydrolyzed to form ______________ before being sent to glycolysis
10
glycolysis has ____ steps
whether or not
glycolysis occurs (only when/whether or not) O2 is present
cytoplasm
glycolysis occurs in the
enzymes called dehydrogenases remove a pair of hydrogen atoms (2 electrons and 2 protons) from the substrate, thereby oxidizing it. the enzyme delivers the 2 electrons along with 1 proton along to its coenzyme, NAD+, forming NADH. the other proton is released as a hydrogen ion (H+) into the surrounding solution.
how does NAD+ trap electrons from glucose and the other organic molecules in food?
when atp concentration begins to drop, respiration speeds up. when theres plenty of ATP, respiration slows down.
how does feedback inhibition/stimulation work in cellular respiration
it can be tapped to make ATP when electrons complete their "fall" in a series of steps down an energy gradient from NADH to oxygen
how does the stored energy in NADH get tapped to make ATP
binding sites; rotor; ATP synthase; spin in a way that catalyzes the phosphorylation of ADP to ATP
in chemiosmosis in cellular respiration, H+ moves into ________________ on the __________________ of __________________, causing it to ________________
lower; liberates energy that becomes available for ATP synthesis
in respiration, the oxidation of glucose transfers electrons to a _________ energy state, which effectively:
proteins, multiprotein complexes
most of the chain's components are _____________, which exist(s) as _______________________________
build their own molecules; biosynthesis, anabolic
not all organic molecules from food are destined to be fuel for ATP. the body uses some small molecules from digestion of food to ______________, a process known as ____________ which is a __________ pathway
the arrangement of electrons in the bonds between their atoms
organic compounds possess potential energy as a result of
the electron transport chain and chemiosmosis
oxidative phosphorylation consists of both
fermentation
partial degradation of sugar that occurs without O2. limited atp produced
3rd, glycolysis, ATP, AMP
phosphofructokinase, the enzyme in the ____ step of ________, is inhibited by _____ and stimulated by ______
combining with the compound oxaloacetate; citrate; citrate; oxaloacetate; acetyl CoA
the acetyl group of acetyl CoA joins the citric acid cycle by ____________________, forming ____________________. the next seven steps decompose the ________________ back to ____________________, which can then be used to bind to more __________________.
exergonic, negative
the breakdown of glucose is ____________, having a ________________ free energy change
aerobic respiration
the catabolic pathway for organic molecules, using O2 as the final electron acceptor in an electron transport chain and ultimately producing ATP
cellular respiration
the catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of ATP
8
the citric acid cycle has _____ steps
reduction
the complete or partial addition of electrons to a substance involved in a redox reaction
oxidation
the complete or partial loss of electrons from a substance involved in a redox reaction
oxidizing agent
the electron acceptor in a redox reaction
reducing agent
the electron donor in a redox reaction
inner membrane of the mitochondria
the electron transport chain is in the
pump H+ from the mitochondrial matrix to the intermembrane space; H+; down its electrochemical gradient back across the membrane; ATP synthase; phosphorolyze ADP to get ATP
the energy released as electrons are passed down the electron transport chain is used to _______________________ . then, ____________ moves _________________________, passing thru _____________________, which uses the energy of that gradient to ___________________
the redox rxns of the electron transport chain; atp synthesis
the energy stored in an H+ gradient across a membrane couples _________________ to _____________________
the sun
the energy stored in organic molecules of food ultimately comes from _____________
regenerate ATP
the energy yielded from cellular respiration is used to
kinase
the family of enzymes used in phosphate transfer
feedback inhibition
the most common mechanism for metabolic control
proton-motive force
the potential energy stored in the form of a proton electrochemical gradient, generated by the pumping of hydrogen ions (H+) across a biological membrane during chemiosmosis
aerobic; anaerobic; aerobic
the term cellular respiration includes both _________ and __________ processes, but primarily refers to ___________________ process
the transfer of electrons. the relocation of electrons releases energy stored in organic molecules, and this energy ultimately is used to synthesize ATP
what releases stored energy in organic molecules during chemical reactions
the oxidized form of nicotinamide adenine dinucleotide, a coenzyme that can accept electrons, becoming NADH. NADH temporarily stores electrons during cellular respiration
whats NAD+
an organic non-protein compound that binds with an enzyme to catalyze a reaction
whats a coenzyme
a sequence of electron carrier molecules (membrane proteins in the inner membrane of mitochondria of eukaryotic cells and the plasma membrane of respiring prokaryotes) that shuttle electrons down a series of redox reactions that release energy used to make ATP
whats an electron transport chain? be sure to comment on the difference bt eukaryotic and prokaryotic cells
the enzyme catalyzed formation of ATP by direct transfer of a phosphate group to ADP from an intermediate substrate in catabolism
whats substrate-level phosphorylation
glucose--> NADH--> electron transport chain--> proton-motive force---> ATP
whats the general energy flow in cellular respiration
1,3,4; pump H+ from matrix to intermembrane space; electrochemical gradient
when complexes ____,_____,and _____ pass electrons thru redox, they ________________________, building ________________________
step 6 of glycolysis. NAD+ reduced to NADH
where does the first redox reaction of cellular respiration occur and whats happening
