M1B: Topic 7 - Cellular Energy

Thermodynamics

The study of energy and energy transfer

• First Law of Thermodynamics: energy cannot

be created or destroyed

• Energy must be transferred from one place to

another

• Potential Energy: stored energy in an object

because of position, arrangement, or state

• Kinetic Energy: Energy of an object due to its

motion

Metabolism

The process of building and breaking down molecules

• Anabolism – use energy to build complex molecules

• Catabolism – break down complex molecules down to release

energy

ATP Production and Energy Storage

Catabolism breaks chemical bonds to release energy

• Energy is stored as ATP

ATP

Adenosine Triphosphate

• Energy “currency” molecule

• concentrated energy in

phosphate bonds

• breaking phosphate bond

releases energy

• ATP  ADP + Pi + Energy

• ADP + Pi + Energy  ATP

ATP Production and Energy Storage

Biomolecules contain energy

• Energy is spread over ALL of the molecule’s

chemical bonds (DIFFUSE)

• Anabolism requires CONCENTRATED energy

• High-energy phosphate bonds of ATP

• Phosphate bond broken to release

energy for anabolism

How do organisms obtain energy?

The sun is the ultimate source of nearly ALL biological energy on earth

• The sun provides light energy for plants to synthesize glucose (anabolism)

• Photosynthesis

• 6CO 2 + 6H2O + Energy  C6H12O 6 + 6O2

• Consumers eat plants and break down glucose to release energy (catabolism)

• Cellular Respiration

• C6H12O 6 + 6O 2  6CO 2 + 6H2O + Energy

Cellular Respiration: Glycolysis

Inputs

• Glucose (C 6H12O6

• 2 ATP

• 2NAD+

• Outputs

• 4 ATP

• 2 NADH

Cellular Respiration: Citric Acid Cycle

Inputs (per glucose)

• 2 Pyruvate

• 8NAD+ + 2FAD

• Outputs (per glucose)

• 2 ATP

• 8 NADH + 2 FADH 2

• 6 CO2

Universal Electron Carriers

NAD+ and FAD

• Derived from B vitamins and

nucleotides

• Carry electrons in high-energy

bonds

• Electrons transferred along

with protons (H+ )

Oxidized form of Universal Electron Carriers

NAD+

• FAD

Reduced form of Universal Electron Carriers

NADH

• FADH2

True or False? Cellular Respiration Happens in the Mitochondria

True

Cellular Respiration: Oxidative Phosphorylation

Inputs (per glucose)

• 10 NADH and 2 FADH

• 6 O2

• Outputs

• 26-28 ATP

• 6 H2O

Electron Transport Chain

Electrons transferred

through a “chain” of

proteins, ending at O2

• Protons are pumped

across membrane

• Generates

electrochemical gradient

• Proton motive force (pmf)

Oxidative Phosphorylation (pt 2)

Protons diffuse down gradient

• Through ATP synthase

• Energy from proton motive force is used to

make high-energy phosphate bonds in ATP

• Lots of ATP generated!

• 26-28 ATP per glucose molecule

How do organisms obtain energy?

The sun is the ultimate source of nearly ALL biological energy on earth

• The sun provides light energy for plants to synthesize glucose (anabolism)

• Photosynthesis

• Light Reactions – light energy converted into ATP

• Dark Reactions – ATP used to synthesize glucose from CO 2

• Consumers eat plants and break down glucose to release energy (catabolism)

• Cellular Respiration

• Glycolysis – glucose is broken down, generating some ATP

• Citric Acid cycle – cyclic process, some ATP made, lots of electron carriers

• Oxidative Phosphorylation – electron carriers used to make LOTS of ATP

Photosynthesis: Light Reactions

Photons excite (energize)

electrons

• Electrons pass through ETC

• Pump protons

• Generate pmf

• ATP synthase converts pmf

into phosphate bonds in ATP

Inputs

• Light (photons)

• H2O

• Outputs

• O2

• ATP

True or False? Photosynthesis happens in chloroplasts

True

Photosynthesis: Calvin Cycle

Inputs

• 6CO2

• 18 ATP

• 12 NADPH

• Outputs

• Glucose (C6H12O6)