Bioenergetics Learning Goals

1. Understand laws of thermodynamics and howthey relate to biological systems

2. Understand that organisms are interdependent, open systems that respond to their environment by managing their energy resources

3. Understand how mitochondria and chloroplasts work with the cell to harvest chemical energy, or convert solar energy to chemical energy

4. Understand the fundamental cellular process of chemiosmosis and its central role in ATP production

Metabolism/Cellular Energetics(The central concept of Semester 1)

• The Good News:• You know most of this stuff already

– Enzymes– Semipermiable Membranes– Active Transport– Potential/Kinetic/

Chemical Energy– Macromoleules/Mono-

mers– ATP– Kinases– Metabolism

• The New Ideas:• Catabolism and Anabolism• The Stages of Cellular

Respiration

• Chemiosmosis• Oxidative Phosphorylation• Light Dependent/Light

Independent Reactions• Photophosphorylation

Key Concepts

• Metabolism

• Energy: Free Energy:

• Spontaneous vs. non spontaneous reactions

• ATP couples Reactions

• Dynamic Equilibrium

College Board “Performance Objectives”

• Describe the role of ATP in coupling a cell’s catabolic and anabolic reactions.

• Explain how chemiosmosis functions in bioenergetics• How are organic molecules broken down by the

catabolic pathways of cellular respiration• Explain the role of oxygen in energy-yielding

pathways of cellular respiration• Explain how cells generate ATP in the absence of

oxygen.

Definitions

• Metabolism:• Metabolic Pathway:• Catabolism:• Anabolism:

Energy

• Energy:

• Kinetic Energy:

• Potential Energy:

• Chemical Energy

The laws of energy transformation• 1st Law of

Thermodynamics:(pg. 143)

• 2nd Law of Thermodynamics:

FIGHT ENTROPY!

More definitions

• Free Energy:

• Exergonic =

• Endergonic =

Changes in Free Energy

How does this apply to Biological Systems?

C: A or BS:

How are Catabolism and Anabolism “coupled”?

The hydrolysis of ATP yields 7.3kCal/mole of ATP

How does this apply to Biological Systems?

What is ATP?

How does ATP Perform Work?

ATP Phosphorylates other molecules!

Examples of ATP at work:

Bioenergetics: The Big Picture

• Producers

• Consumers

Producers: convert solar energy into chemical energy

Producers: convert solar energy into chemical energy

How does Bioenergetics relate to other concepts in Biology?

Bioenergetics: The Big Picture

• The Equations:

• In general…– Organic Molecules– Food

• Combustion or Oxidation of Glucose (∆G) = • Number of ATP/Glucose Molecule

• Regeneration of ATP (from ADP & Pi) (∆G) =

Consumers (start with organic molecules, give off CO2)

• Some Details:

Glycolysis

– Fermentation Cellular Respiration

These are re-dox reactions

Cellular Respiration

• Oxidation of Food Molecules by Oxygen– Releases Energy

• Cumulative Function of 3 metabolic stages

• Glycolysis

• Citric Acid (Kreb’s) Cycle

• Oxidative Phosphorylation

Cellular Respiration Where…How…Connections

Our Objective

• Learn the important details about the 3 metabolic stages of cellular respiration

• Glycolysis, Citric Acid Cycle, Oxidative Phosphorylation

• Remember that the cell is using glucose to make ATP (it’s harvesting energy)

• Remember these stages are connected!

SLP: Substrate Level Phosphorylation

Glycolysis

• Literally…

• (2 phases)

Fig 9.8

Glycolysis 1: Energy Investment

• What happens, why?

• What’s the “end” product?

Glycolysis 2: Energy Return• G3P is…

• SLP…

• The “end” product(s):– ATP– NADH– Pyruvate

Connections: Pyruvate is Oxidized

1)

2)

3)

Citric Acid Cycle:

• It is a cycle!

• Where does it happen?

• What are the outcomes?

Oxaloacetate(4-C)

Citrate(6-C)

Citric Acid Cycle:The Bottom Line…

Pyruvate is completely oxidized and the energy is converted to NADH and FADH2 (ETC) and ATP via S.L.P.

8 NADH and 2 FADH2 per glucose molecule

The intersection between Glycolysis and OXY PHOS

Oxidatative Phosphorylation Overview:

During oxidative phosphorylation, chemiosmosis couples electron transport to ATP Synthesis.

• Where?

• What?

• How?

• What else happens?

Oxidative Phosphorylation 1:E.T.C.

P.C.

Oxidative Phosphorylation 2

• So What?– E.T.C. drives…

– ATP Synthase

Oxidative Phosphorylation 3: Putting it all together

[ ]

[ ]

Chemiosmosis!An energy-coupling

mechanism that uses energy stored in the form of a H+ gradient across a membrane to drive cellular work.

1)

2)

3)

1)

2)

3)

Hints for building ETC Model1. Start with aligning yourselves from least electronegative

(greatest Potential energy) to most electronegative. This should be a physical change in height. Use stools, chairs, bench tops etc.

2. Get comfortable passing electrons down from least electronegative molecule to most electronegative molecule. (I suggest saying “Grrrr” when you get reduced. Perhaps the “Grrr” gets louder as electo-negativity increases.)

3. Once you are comfortable passing electrons, add in the protons moving across the protein complexes, into the intermembrane space and then through ATP synthase to generate ATP.

4. Use your textbook, each other, and me as a resource. I will be videotaping the process and product.

Cellular Respiration: Review (F9.16)(don’t look at the book, let’s work this out together.)

Reactants, Products, major intermediates, processes, specific locations

Net ATP Production

Mode of ATP Production

ATP Accounting?• Catabolism of Glucose, ∆G = -686 kCal/mol

• Anabolism of ATP from ADP + Pi, ∆G = 7.3 kCal/mol

• About 36-38 mol ATP/mol glucose• ATP synthesis is roughly… …efficient• Where does the rest of the energy go?

ATP/NADH

ATP/FADH2

ATP/H+

Beyond Cellular Respiration

Fermentation: an alternate pathway for energy production (ATP synthesis)

• Fermentation is…

• fermentation starts with...

• F.A…

• O.A…

Fermentation: (2 processes)

• What do these pathways have in common?

• What’s different?

• What’s the significance of alcohol fermentation?

• What’s the significance of lactic acid fermentation?

• What else do these pathways have in common?

Comparing Fermentation and Cellular Respiration

• Commonalities:

• Differences:

Oxidative Phosphorylation

Glycolysis is ancient…

• How old is it?– Est. to be ________

• What else do we know– – – –

Regulation of Cellular Respiration

Enzymatic Regulation: Allosteric Regulation

Fluctuating concentrations

ATP vs. ADP + Pi

Life on Earth is solar powered

Bioenergetics: Background Info

• Producers

• Consumers

Photosynthesis: Biochemistry conserved throughout several Domains

Across four levels of organization

• Plants • Leaves

• Mesophyll Cells

• Chloroplasts

A Closer Look at the Organelles

PS: 2 Reactions in 1 organelle

Food for thought:

How are cellular respiration and photosynthesis similar? How are they different? Think about it on

an organismal level, on an organelle level, and on a biochemical level.

More Food…Check out Figure 10.16

Light Reactions begin with…

• Light (Visible Light)• • • • • •

is Absorbed by 3 Pigments

• Chlorophyll a

• Chlorophyll b

• Carotenoids

Why peaks?

So What? • So what happens when

light is absorbed?

photosystem

If photosystems are membrane-bound, then you can build a “battery”

If we could get down on the thylakoid membrane…

No, really, so what?

• Where does the electron from water go once it replaces the electron in the chlorophyll molecule in the center of PSII (PS 680)?

Just a few questions, if you please

• Is there any oxidation happening?• Is there any reduction happening?• Is there any catabolism happening• Is there any anabolism happening?• Is there any coupling occuring?• What is this process called?

What happens? Well, chemiosmosis happens.

What do the Light Reactions produce?

• Light Reactions…

Light Reaction Review…

Gimmie Some Sugar!

Photosynthesis: The Big Picture

Location

Energy conversions

Material inputs/outputs