ch9 - making atp

7/29/2019 Ch9 - Making ATP

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Chapter 9 Making ATP

What is the function of ATP?

- to provide E for cellular processes

organisms dont eat ATP; they need to make

it

- that requires E from outside

- that E could come from light (the sun)

or as the PE in molecules (like sugars)


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E enters most ecosystems as __________

photosynthetic spp. transform light E into PE

in the bonds of organic molecules

the breakdown of those molecules can

release the E

used to make

ADP + Pi ATP

ATP is constantly made and used

- a working muscle cell recycles all its ATP in< 1 minute

- = ~ 10 million molecules / second

- we use nearly our body weight worth ofATP/day


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ATP can be made via 2 possible pathways:

i) cellular respiration

ii) fermentation

but first, a little background info


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both photosynthesis and cellular respiration

involve oxidation-reduction (redox)

reactions

oxidation:

reduction:

redox can also occur in covalent situations:

- if reaction results in e- being held by a

more electronegative atom

- e.g. non polar bonds polar


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Why is E released?

takes E to pull an e- from an atom

the more electronegative, the more E it takes

allowing e- to fall closer to a more

electronegative atom releases PE and s

stability

e.g.

2 H H + O O


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e.g. cellular respiration:

C6H12O6 + 6O2 6CO2 + 6H2O + E


C6H12O6 + 6O2 6CO2 + 6H2O + E


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C6H12O6 + 6O2 6CO2 + 6H2O + E

occurs as a seriesof reactions (a pathway)

enzymes pluck off Hs andseparate them into H+ and e-


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enzymes pluck off Hs and separate

them into H+ and e-

the e-s pass thru series of ever-moreelectronegative molecules

(redox reactions release a little E)

final e- acceptor is ____ ( H2O)

whole process = an __ ________ _____

the first molecule to accept the e-

isNAD+ ( )

NAD+ can grab 2 high-energy e- and one H+

NADH (is now reduced + has more PE)

NADH then passes on the e-

s (to e-

transportchain) and turns back into NAD+


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Cellular Respiration has 3 stages:

glycolysis citric acid cycle e- transport

chain

in cytosol matrix inner membrane

mitochondria

1) Glycolysis

10 steps

overall:

glucose pyruvate

(6 C) (2 x 3C)


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2) Citric Acid Cycle

further breaks down pyruvate

pyruvate CO2(3C)

acetyl coenzyme A (2C)

2 CO2

3) The e-

Transport Chain e- (delivered by NADH

and FADH2) passed

from molecule to

molecule

lose PE at each step

used to make ATP(but with an

intermediate step)


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E released by e- flow is used to pump H+ from

matrix to intermembrane space

creates a [H+] gradient (i.e. a different form of PE)

H+

ions flow back into matrix thru ___________

which then makes ATP

(= _________ ____________)

produces 32 34 ATP/glucose


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An overview of cellular respiration

~ 40% efficient


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Some Respiratory Poisons:

i) cyanide:

- clogs up e- transport chain by blocking flow

of e- to O2

- no H+ pumping

no H+ gradient

no H+ flow thru ATP synthase

no ATP made

ii) ATP synthase inhibitors

[H+] gradient forms, but no ATP made

e.g. oligomycin (an antibiotic)


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iii) uncouplers

make inner membrane leaky to H+

e- transport chain continues

H+ diffuse inwards but not thru ATP synthase

no ATP made

Fermentation

an alternate way to transfer E in sugar into E

in ATP

has 2 parts:

i) glycolysis (this makes the ATP)

ii) a mechanism to turn NADH back into NAD+

notice: no Citric Acid Cycle or e- transport chain,

does not need O2

different types named for their waste products:


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a) Alcohol Fermentation

in some bacteria and fungi (e.g. yeasts)

glucose pyruvate

2 ADP, 2 Pi 2 ATP

2 NAD+ 2 NADH

will stop if it runs out of NAD+


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b) lactic acid fermentation

some bacteria, some fungi

+ mammal skeletal muscle cells(if short on O2)

regeneration of NAD+ converts pyruvate to

lactic acid

used to produce cheese, yogurt

glucose pyruvate

2 ADP, 2 Pi 2 ATP

2 NAD+ 2 NADH


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Fermentations

advantage:

disadvantage:

Vocab.: strict aerobes

strict anaerobes

facultative anaerobes


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Making ATP using molecules other than

glucose

i) di and polysaccharides

hydrolysis to monos

fats

glycerol

fatty acids

broken into 2C pieces

acetyl coenzyme A

to

joins glycolysis part way

through


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iii) proteins

amino acids

de-amination

intermediate of

glycolysis or citric

acid cyclenitrogenous waste (NH3, urea)

out of body (urine)

Metabolic pathways can be used to transformcompounds

e.g. pasta (polysaccharides)

glucose

acetyl coenzyme A

fatty acids + glycerol

fat

via glycolysis

ch9 - making atp

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