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