Cellular Respiration

Remember

• 1. ETC is a series of Redox on a membrane used to create a [] leading to PE.

• 2. CHOs are made in photosynthesis

Energy Coupling between Photosynthesis and Cellular

Respiration

ECOSYSTEM

Lightenergy

Photosynthesisin chloroplasts

Cellular respirationin mitochondria

Organicmolecules

+ O2CO2 + H2O

ATP

powers most cellular work

Heatenergy

Cell Respiration is Catabolism

• Use O2 to make ATP.• With O2 energy is made in mitochondria• Without O2 energy is made in cytoplasm• - G because its catabolic and exergonic.• There is free energy to do work.

Catabolism• Process where molecules are broken down,

and their energy is released. Two types.• Fermentation-partial degradation of sugars

that occurs without the use of oxygen. (anerobic respiration)

• Cellular respiration- most prevalent and efficient metabolic pathway. Oxygen is consumed as a reactant along with organic fuel. (aerobic respiration)

Photosynthesis and Cellular Respiration chemical reactions

(Remember… conservation of matter.)

6 CO2 + 6 H2O C6H12O6 + 6 O2 + Heat

Photosynthesis

C6H12O6 + 6O2 6CO2 + 6H2O + Heat + Free E

Cellular Respiration

ATP Structure

Cell Respiration has 3 steps

• 1. Glycolysis• 2. Kreb’s Cycle or CAC• 3. ETC aka Oxidative Phosphorylation aka

Chemiosmosis

Glycolysis• Occurs in cytosol• This process occurs with/

without O2 in the cytolasm.• All organisms can do this…

evolution…life before O2.

• Glycolysis Animation• Better Glycolysis Animation

Glycolysis Step-by-Step• 1. Start with a 6C hexose sugar.• 2. 2 PO4 are added to glucose using up 2ATP creating

a 6C sugar diphosphate +2ADP. • 3. 6C sugar splits into 2 G3P molecules.• 4. NAD+ (e- carrier) adds PO4, removes a H+ from

the 3C sugar and turns into NADH . The 2 G3P sugars turn into 2 3C sugars called pyruvate by the removal of both phosphates.

• 5. Each 3C sugar yields 2ATP when converted from sugar phosphate to pyruvate.

Summary of Glycolysis

I. Glycolysis-cytoplasm-

Glucose----> 2 pyruvic acid

2NAD + 2H---->2NADH

2ATP---->2ADP + 2P

4ADP + 4P----> 4ATP

NET 2 ATP for cell use

After Glycoysis

• If oxygen is present: aerobic respiration– Aerobic respiration= glycolysis+CAC+OP

• If oxygen is absent: anerobic respiration– Anerobic respiration =glycolysis + fermentation

Is Oxygen present?

Fermentation

• Two types of Fermentation:– 1. Alcohol fermentation- pyruvate is converted

into ethanol.– 2. Lactic acid fermentation- pyruvate is reduced

(gains electrons from NADH+). (NADH+ NAD+)Lactate formed as waste product.

Cellular Respiration• Carbohydrates, fats, and proteins can all be

broken down by C.R.• Glucose most common molecule broken

down by aerobic respiration.• 6O2 + C6H12O6 -->  6H2O + 6CO2 + energy

• Exergonic release of energy is used to phosphorylate ADP to ATP.

• The goal of cellular respiration is to regenerate ATP that is used by cells as main energy source. (ADP + P ATP)

Oxidation-Reduction Reactions• Cellular Respiration - YouTube• Cellular respiration is an example of an

oxidation reduction reaction. (Redox for short)• In redox reactions electrons are transferred

from one reactant to another.• When a reactant loses electrons it is called

oxidation. This causes a loss of energy.• When a reactant gains electrons it is reduced.

This causes a gain of energy

Another way a cell uses energy is by moving hydrogen, and electrons around. Giving a molecule hydrogen, increases the energy content of that molecule .

For example compare gasoline with carbon dioxide. Which has more energy? Now look at their molecular structure

Oxidizing a molecule, decreases the energy content of that molecule and reducing a molecule increases the energy content of that molecule.

Oxidized Reduce

1. Remove H 1. Add H

2. Remove e- 2. Add e-

3. Add oxygen 3.Remove oxygen

When NAD+ gains 2 electrons and hydrogen it is called NADH and when NADP+ gains 2 electrons and hydrogen it is called NADPH. Look at NAD+ and NADH and see where the extra hydrogen is

Compare FAD and FADH2 and determine what is the difference between these two hydrogen carriers.

Following Glycolysis with Oxygen

• Glycolysis takes place in cytosol.• If oxygen is present, the pyruvate goes into

the mitochondria to complete the second stage of cellular respiration: Citric Acid Cycle aka Kreb’s Cycle

Citric Acid Cycle

• Citric Acid Cycle

• Main purpose of Kreb’s is to make electron carriers for

Citric Acid Cycle Step by Step• 1. Pyruvate (3C) loses CO2, becomes 2C,

NAD is reduced to NADH +H+, Coenzyme A joins the molecule and is now called Acetyl-CoA (2).– Happens between outer and inner m. membrane

• 2. Acetyl CoA joins a 4C molecule forming a 6C molecule and Coenzyme A is released.

• 3. 6C molecule is oxidized, another NAD+ is reduced to NADH, CO2 is released, and 5C molecule results.

• 4. 5C molecule oxidized again, another NAD+ reduced to NADH, CO2 released, 1ATP generated, and a 4C molecule results.

• 5. 4C molecule is oxidized, FADH to FADH2, NAD+ TO NADH, and the 4C molecule is ready to rejoin the acetyl CoA and start the cycle again.

• Citric Acid Cycle

CoA

Actual Kreb’s Cycle

Summary of Krebs- Occurs in mitochondrion

2X’s

Pyruvate---> 3 CO2 6 CO2

1 ADP ---> 1 ATP 2 ATP

4 NAD ---> 4 NADH2 8 NADH

1 FAD ---> 1 FADH2 2 FADH2

The hydrogen found on pyruvate will be used to reduce NAD and FAD. Only one ADP is phosphorylated at the substrate level or directly by enzymes.

Glycolysis and Citric Acid Cycle are both substrate level

phosphorylation

Step 3 of Cellular Respiration utilizes the process of oxidative

phosphorylation.

Step 3:Oxidative Phosphorylation aka

Chemiosmosis• Located in cristae of mitochondria is the electron transport chain. More folds=more ATP produced.

• ETC will make more ATP using NADH & FADH2.

• Electrons from NADH & FADH2 will move down the ETC and pump H+ across the cristae membrane.

• NADH & FADH are oxidized, and ADP is phosphorylated.

Oxidative Phosphorylation• Each NADH =6H+• Each FADH2=4H+• ~2H+=1ATP

• Notice outside the the difference in (+) and (-)

• ATP synthase uses the osmotic difference to allow H+ to go back into the matrix.

• Oxygen is the final e- acceptor.

8 NADH2 x 6 H = 48 H+

2 FADH2(Krebs)x 4 H = 8 H+

2 FADH2(glyc.) X 4 H = 8 H+ ATP Summary

64 H+ 64 H+ --> 32 ATP

Electron Transport Chain• Electron transport chain powered by

electrons from NADH and FADH. • As these electrons lose energy, that energy

is used to pump H+ into intermembrane space.

• At end of ETC, hydrogen bonds to oxygen to form water. No oxygen the process stops.

• Cellular Respiration (Electron Transport Chain)

• ATP Synthase

Chemiosmosis

• Hydrogen ions will flow back down concentration gradient through a transmembrane protein called ATP synthase.

• The H ions provide a concentration gradient (fuel) that drives ATP synthesis.

• ADPATP in this step

Oxidative Phosphorylation• This term is used because ADP is

phosphorylated into ATP, and oxygen is necessary to keep electrons flowing in the ETC.

• Total ATP Yield for Cellular Respiration: 36-38 ATP.

• 32-34 ATP come from oxidative phosphorylation.

“Building” the proton concentration gradient

Protein complexof electroncarriers

H+

ATP ATP ATP

GlycolysisOxidative

phosphorylation:electron transportand chemiosmosis

Citricacidcycle

H+

Q

IIII

II

FADFADH2

+ H+NADH NAD+

(carrying electronsfrom food)

Innermitochondrialmembrane

Innermitochondrialmembrane

Mitochondrialmatrix

Intermembranespace

H+

H+

Cyt c

IV

2H+ + 1/2 O2 H2O

ADP +

H+

ATP

ATPsynthase

Electron transport chainElectron transport and pumping of protons (H+),

Which create an H+ gradient across the membrane

P i

ChemiosmosisATP synthesis powered by the flowof H+ back across the membrane

Oxidative phosphorylation

ATP Synthetase Complex using kinetic movement of H+ (protons)

ATP WEBSITE

• ATPl• Oxidative Phosphorylation Animation• You Tube- ox phos• cellrespiration

review song- Black Eyed Peas

Data Set 4 Picture

A

B

C

D

• The correct answer is B. This species is not struggling to exist. The environment is very favorable as it is making and storing more energy than it is consuming on metabolism, growth, repair, and reproduction. It has energy to spare.

•  • Answer A is incorrect because species B is consuming more energy

than it can produce. It must be a harsh environment because it is consuming more energy trying to “stay alive”. At this pace, it will eventually die from an energy production deficit.

• Answer C is incorrect because species D, while very much in the “high green” part of the curve, is only still at the

• breakeven point on the y axis. Life is a struggle to exist here because any little disruption to the environment may put the species in a energy deficit situation where Cellular respiration is consuming more energy than being produced.

• Answer D is incorrect for same reason as answer C.

Cellular Respiration Lab (Lab #5)• Lab 5 Set Up• Make sure to time

calibration times!• Practice drawing cell

respiration on boards in down time.

• Practice writing out steps in down time.

• Begin answering questions.