cellular respiration-may 3

7/31/2019 Cellular Respiration-May 3

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Chapter 9:

Cellular RespirationHarvesting

Chemical Energy


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O

xidationand

Re

duc

tion

Oxidation is the Loss of Electrons

E.g., something that is oxidized in the course of a

chemical reaction with Oxygen has had electronsstolenby Oxygen

Reduction is the Gain of Elections

E.g., a gain of electrons results in a decrease(reduction) in electrical charge (since electrons carry

a negative charge)

Metal ores are Reduced to metals (via the addition

of electrons)metals found in ores are in an oxidized

form relative to metals found as metals


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ATP Genesis in Eukaryotes


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Glycoslysis

Glycolysis feeds material toelectron transport chains plus

makes ATP in its own right

Note in eukartyotic cellsthat glycolysis takes

place in the cytoplasm,i.e., outside of the

mitochondria


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Glucose P

P

Glyceraldehyde

3-phosphate (x2)

PP

Pi

ATP

ADP

ATP

ADP

+ NAD+

+ NADH + H+ (2x)

ATP(2x)

ATP(2x)

1,3-biphosphoglycerate

(2x)

cellular respirationor fermentation

cellular respiration

or fermentation

Fructose

1,6-biphosphate

Pyruvate (x2)


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Step

so

fG

lyco

lys

is First priming

ATP

Phosphorylatedhexose


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Step

so

fG

lyco

lys

is

Secondpriming ATP

Isomerizationstep

BiphosphorylatedHexose


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Step

so

fG

lyco

lys

is

Sugar-splitting(glyo-lysis) step Phosphorylated

trioses


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Step

so

fG

lyco

lys

isThis reaction is driven to the right bythe removal of reactant to the right

Note that these are phosphorylatedversions of the two simplest sugars


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Step

so

fG

lyco

lys

is

Noteinorganic

phosphate

This iswhere

NAD+ isrequired

Note that stoichiometry istwo of these reactionpathways per starting

glucose (hence the 2s)


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Glyceraldehyde-3-Phosphate Dehydrogenase

enzyme

substrates

products

Have to have NAD+for glycolysis to work


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Step

so

fG

lyco

lys

is

First ATPsproduced (2)

This is asubstrate-levelphosphorylation

step

Movement ofphosphate


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Step

so

fG

lyco

lys

is

Second ATPsproduced (2)

Increase in

electron densitynear phosphate

Three-carbonproduct


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Into the Mitochondria

Oxidation ofpyruvate step


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Oxidation of Pyruvate

Production of

first CO2

2nd

and 3rd

NADH


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Removal of Rest of CO2s and Energy

Krebs cycleconverts

remainingcarbons (2 x 2)

to CO2s


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Ou

tlin

eo

fKre

bs

Cyc

le

Note that thereare 2 AcetylCoAs per

glucose so 2turns perglucose

Substrate-levelphosphorylation


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Kre

bs

Cycle

inDe

tail

Note acetyl CoA

Note citric acid

Noteconversion of

carboxylgroups to

CO2

Noteformation of

FADH2


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Electron Transport & Oxidative Phosphorylation


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Elec

tron

Trans

port

Sy

stem

Note differentlocations ofaddition of

electrons

Note additionof both

electrons and

protons tooxygen

Not shown isproton

pumping!

Series of

redoxreactions


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ATP Bookkeeping


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ATP

Book

keepin

g

One glucose yields:

2 ATP in glycolysis

2 NADH in glycolysis

2 NADH as pyruvate enters citric acid cycle

2 ATP in citric acid cycle

6 NADH in citric acid cycle 2 FADH2 in citric acid cycle

Thats 2 + 6 2 + 6 + 2 + 18 + 4 = 36

The 2 is an NADH transportation into the

mitochondria cost

Thats 2 + 6 0 + 6 + 2 + 18 + 4 = 38 in bacteria(where cytosol and inside of mitochondrium are

equivalent)


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Anaerobic Respiration

employs an

inorganicmolecule otherthan O2 as a

terminal electronacceptor.

Less ATP is

produced becausethese electron

acceptors requiremore energetic

electrons


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F

ermen

tation

Alternativemeans of NAD+

regeneration


27/27L

ac

ticA

cidFe

rmenta

tion

To glycolysis

cellular respiration-may 3

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