Bio Exam 3 Material

ETC (Electron Transport Chain)

• Consist of protein complexes in the inner mitochondrial membrane

• Energy from transferring electrons is used to pump H+ from the matrix to the

inter membrane space creating a H+ gradient = proton motive force

Loss of Electrons is

Oxidation

1,3, and 4 are pumps

They pump hydrogen ions across the membrane

1,3 and 4 get energy from

Electrons

Nadh gets droppef off at 1 and gets shudled to 3 by

Q

With each transfer of electrons

Energy is decreased

FADH 2

Is more electronegative than complex 1

Complex 2 is able to get

Electrons from FADH

The whole purpose of the ETC

Form a hydrogen ion gradient

02 Is the final electron acceptor in the

ETC

ETC forms

Hydrogen ion gradient but no ATP

ATP Synthase (think of a windmill)

• H+ flows down its gradient through ATP synthase.

“Chemiosmosis”

• Energy from release of gradient is used to make ATP. 

Most of the ATP in cellular respiration are generated through

electron transport & oxidative phosphorylation

You breath oxygen to…

Serve as the final electron acceptor in the electron transport chain

ETC Blockers

– Inhibit flow of electrons & pumping of H+ by ETC

– Prevent formation of H+ gradient

Rotenone

• Disrupts electron transport in metabolism

Block electron transport

Cyanide or CO (Block at 4) 

Uncouplers

– Allow pumping of H+, but disconnect it from ATP synthesis

– Let H+ sneak back into matrix without using ATP synthase

Uncoupling protein

• Allow formation of H+

• Disconnect gradient from ATP synthesis - H+ move back into matrix

without using ATP synthase (generate heat instead of ATP)

Cyanide and carbon monoxide block the protein that donates the

electrons to oxygen, thus forming water. Cyanide and carbon

monoxide block ATP synthesis by

preventing the formation of an H+ ion concentration

gradient.

Drugs known as uncouplers facilitate diffusion of protons across the

membrane. With an uncoupler, what will happen to ATP synthesis and

oxygen consumption?

ATP synthesis will decrease; oxygen consumption will greatly

increase.

ATP Synthase inhibitors

– Allow electron flow & creation of H+ gradient

– Directly inhibit activity of ATP synthase

Carbohydrates are

Polar

We tend to burn

Carbs and Fats first

Relationship between photosynthesis & aerobic
respiration

NADPH

Electron Carryier

How does Respiration relate to Photosynthesis?

• Respiration – oxidation of sugars to generate ATP.

What does it use? What does it produce?

• Photosynthesis – reduction of CO2 and water to

build sugar. What does it use? What does it

produce?

Autotroph

produce complex

organic molecules (e.g., glucose,

starch) from simple inorganic

molecules (e.g., CO2, H2O)

Photoautotroph

transform

radiant energy (sunlight) into

chemical energy (ATP) to produce

complex organic molecules (e.g.,

glucose, starch) from simple

inorganic molecules (e.g., CO2,

H2O)

What is a photoautotrophs

Plants, protists and prokaryotes can all be

photosynthetic

Anoxygenic Photosynthesis:

no O2 produced; purple & green bacteria

Oxygenic Photosynthesis:

O2 produced; cyanobacteria, many protists, most green plants.

Producers store potential energy in

covalent bonds of the sugars, starch, etc

Why do apple trees (autotrophs) produce starch?

- Starch is used to fuel respiration

Stomata can be opened and closed to exchange

gases and to regulate H2O loss

Photosynthesis consists of two sets of reactions

Photosynthesis Inside a Leaf

Photosynthesis starts in the photosystems of a thylakoid – Photosystems contain pigment molecules

Light

• Light is a form of energy

• Different wavelengths contain different amounts of energy

• Pigment molecules in chloroplasts absorb light energy

• The pigment in human eyes is retina

Pigments in plants

Pigments (mostly chlorophyll) give leaves their characteristic green color

Chlorophyll is

The main pigment in plants

Carotenoids are accessory

pigments

They capture wavelengths

not efficiently absorbed

by chlorophyll

Carotenoids

are accessory pigments, they capture wavelengths not efficiently absorbed by chlorophyll

Chlorophyll absorbs light energy

Multiple chlorophyll molecules

function together with thylakoid

membranes

Chlorophyll molecules and

accessory pigments are assembled

into…

antennas

About ___ chlorophyll molecules

per antenna

300

Photosystem I

Absorbs longer wavelength

light and funnels energy to a

special chlorophyll a molecule

called P700

Photosystem II 

Absorbs shorter wavelength

light and funnels energy to a

special chlorophyll a molecule

called P680

What is the ultimate purpose of exciting an

electron from chlorophyll?

The excited electron is donated to an electron acceptor.

If one molecule is being  ____ (NADP+ to

NADPH, another molecule is being ____

Reduced, Oxidized

WATER gets ____ and serves as the electron

donor

Oxidized

Thylakoid membranes are packed with photosystems

and ATP synthase

Which of the following are produced

during the Calvin cycle?

glucose, ADP, NADP+