biochemistry lect 5 2011 colour 2 slides per page

8/13/2019 Biochemistry Lect 5 2011 Colour 2 Slides Per Page

1/11

Fig. 4.6 Control of the

citric acid cycle

From: Biochemistry, 5th Edition,

Berg, Tymoczico and Stryer

LECTURE 5: You just cant get away from

electrons!

Key Concepts (the big picture):Key Concepts (the big picture):

the energy from the oxidation of fuels is converted to

ATP by the process of oxidative phosphorylation

oxidative phosphorylation involves the transfer of

electrons to oxygen and the synthesis of ATP

oxidative phosphorylation takes place in mitochondria

the location and number of mitochondria is correlated

with the energy demands of different tissues


2/11

WHAT YOU NEED TO KNOW!! You shouldWHAT YOU NEED TO KNOW!! You should:

understand how the ener from the trans ort of

electrons to O2 is transformed into the high energy

phosphate bonds of ATP.

understand why the net yield of oxidative

phosphorylation is about 1.5 2.5 moles of ATP per

mole of NADH oxidized or 1.5 moles of ATP per mole of

.

be familiar with the electron transport carriers which

transfer electrons from NADH/FADH2 to O2

understand the chemiosmotic coupling hypothesis

and the role of ATP synthase

Reading: (for onReading: (for on--line testing)line testing)


3/11

Fig. 5.1 The catabolism of various food molecules

Fig. 5.2 Free-energy change during electron transport


4/11

Fig 5.3: Oxidative metabolism in mitochondria

Starvation and stress-induced elongation of mitochondria.

- starvation elicits a number of cellular responses to retrieve nutrients

- mitochondrial fusion enhances ATP production


5/11

Fig. 5.4a: Essence of oxidative phosphorylation

From: Biochemistry (5th edition) Berg, Tymoczico and Stryer)

Oxidation and ATP synthesis are coupled by transmembrane proton fluxes

Fig 5.4b Schematicrepresentation of

the link between

respiration and

ATP roduction

Step 1

Step 2

Step 3

PROTON MOTIVE FORCE(CHEMI-OSMOTIC

GRADIENT)


6/11

From Bioenergetics An Introduction to the Chemiosmotic Theory

David G. Nicholls. Academic Press London New York 1982

Animation: Chemiosmosis: How the mitochondrial membrane

couples electron transport to oxidative phosphorylation


7/11

Animation: Chemiosmosis: How the mitochondrial membrane

couples electron transport to oxidative phosphorylation

FADH2

FAD

Fig. 5.5 Chemiosmosis


8/11


9/11

ELECTRON TRANSFER COMPLEXES

COMPLEX 1

NADH DEHYDROGENASE contains FMN and FeS

COMPLEX 2

SUCCINATE DEHYDROGENASE- contains FAD and FeS

COMPLEX 3

CYTOCHROME bc1 contains heme and FeS

COMPLEX 4CYTOCHROME c OXIDASE- contains heme and Cu

CYTOCHROME c and CoQ

Fig. 6.5 Chemiosmosis


10/11

Electron Micrograph of mitochondrion

showing ATP Synthase


11/11

INTERMEMBRANE SPACE

Rotor

H+

Stator

H+ ions flowing down theirgradient enter a half channel in

a stator, which is anchored in

the membrane.

H+

ions enter binding siteswithin a rotor, changing the

shape of each subunit so that

the rotor spins within the

Fig 5.6: ATP

synthase, a

molecular

machine

Internalrod

Cata-

.

Each H+ ion makes onecomplete turn before leaving

the rotor and passing through a

second half channel in the

stator into the mitochondrial

matrix.

Spinning of the rotorcauses an internal rod to s in

lyticknob

ADP+

P ATPi

MITOCHONDRIAL MATRIX

as well. This rod extends like a

stalk into the knob below it,

which is held stationary by part

of the stator.

Turning of the rod activatescatalytic sites in the knob that

produce ATP from ADP and Pi.

biochemistry lect 5 2011 colour 2 slides per page

Documents