Lecture 6 Outline (Ch. 9, 10)

I. Citric Acid Cycle

II. Electron transport chain & oxidative phosphorylation

III. Anaerobic respiration

IV. Respiration with other molecules

V. Chloroplasts

VI. Light

VI. Summary

Steps of Respiration

Glucose is OXIDIZED/REDUCED to _____.Oxygen is OXIDIZED/REDUCED to _____.

Steps of Respiration

• Stages of respiration:

3. Citric acid cycle

Mitochondrial matrix

e- transfer: redox

Cellular Respiration

3. Citric acid cycle

• 2 Acetyl CoA (2C) join oxaloacetate (4C)

• few ATP so far

• e- to carriers

(NAD+, FAD)

• now in mito. matrix

• 2 citrate (6C) converted several steps, 4C lost (CO2)

• 2 ATP made

Where do the outputs go?

In thinking about cellular respiration:

a. What is/are the overall function(s) of glycolysis?

b. What is/are the overall function(s) of pyruvate oxidation and the Krebs cycle?

Steps of Respiration• Stages of respiration:

4. ETC

Cellular Respiration

• ETC e- collection molecules

• embedded on inner mitochondrial membrane

Electron transport chain (ETC)

• accept e- in turn

• e- ultimately accepted by O2

(O2 reduced to H2O)

~100 H+ (stored)

10 H2O

-outputs:

ATP (none yet)

Where do outputs go?

Electron transport chain (ETC)

-inputs:per glucose,

10 NADH

2 FADH2

Cellular Respiration 4. Chemiosmosis

• ATP synthase: inner mitochondrial membrane

• H+ stock-piled in inner membrane space = gradient

• chemiosmosis – ion gradient to do work

Cellular Respiration

• ATP synthase: enzyme that makes ATP using H+ gradient

3. Chemiosmosis

• H+ must enter matrix here

• Generates 1 ATP per ~3.4 H+

In thinking about cellular respiration:

a. At what stage(s) in the overall process is each of the

reactants used?

b. At what stage(s) in the overall process is each of the products

produced?

C6H12O6 + O2 CO2 + H2O + Energy

Cellular RespirationSummary of respiration

KNOW THIS DIAGRAM – EXCELLENT SUMMARY

Cellular Respiration - anaerobic

• no O2 – no oxidative phosphorylation

• fermentation = extension of glycolysis

Cellular Respiration - anaerobic

• Types of fermentation -

1. alcohol

• pyruvate converted to acetaldehyde

• acetaldehyde accepts e- to regenerate NAD+

• ethanol produced

• brewing & baking

Cellular Respiration - anaerobic

• pyruvate accepts e- to regenerate NAD+

• lactate produced

• Types of fermentation -

2. Lactic acid

• muscle fatigue & dairy industry

Cellular Respiration

• Comparison of aerobic vs. anaerobic respiration:

• ATP per glucose:

Aerobic Anaerobic

• initial e- acceptor:

• final e- acceptor:

Let’s say it takes 1,000 g of glucose to grow 10 g of yeast anaerobically.

How many grams of glucose would it take (estimate approximately) to grow 10 g of yeast aerobically?

Hint: If it takes X amount of glucose to grow 10 g of yeast without oxygen, what factor would you have to multiply or divide X by to grow 10 g of the same yeast with oxygen?

Cellular Respiration – other biomolecules

• Glucose catabolism – one option

• Proteins:

• Fats: enter CAC or before

Catabolized into a.a.

Amino group removed (pee out in urine)

• If have more glucose than needed, can run “backward” to store energy as glycogen or fats!

Self-Check

Step of Respiration

Inputs Outputs CO2/H2O ATP produced

e- carriers loaded

Glycolysis 1 glucose 2 pyruvate None 2 net 2 NADH

Coenzyme Junction

Citric Acid Cycle

Electron Transport Chain

Oxidative phosphorylation & Chemiosmosis

Fermentation

Photosynthesis - overview

Overall purpose:

Photosynthesis - overview

• photosynthesis:

light chemical energy

• complements respiration

- light reaction: solar energy harvest

- Calvin cycle: energy to organics

chloroplast recap

Outer membrane

Inner membrane

Thylakoid membrane

Intermembrane space

Stroma

Thylakoid space

Photosynthesis - overview

• Photosynthesis -

1. light reaction: store energy & split water

NADPH & ATP given off

Chloroplast model:

H2O + CO2 + energy C6H12O6 + O2

In photosynthesis,

water is OXIDIZED/REDUCED to _______ and

carbon dioxide is OXIDIZED/REDUCED to ______.

Redox Reactions

Equation for photosynthesis

CO2 + H2O + light energy C6H12O6 + O2

photo synthesis

Photosynthesis – light absorption

• visible light ~380 to 750 nm

• chloroplast pigments – absorb blue-violet & red/orange

- transmit and reflect green

• pigments:

• chlorophyll a

• accessory pigments

-energy-absorbing ring

-hydrocarbon tail

- carotenoids

- photoprotective

Photosynthesis – light absorption

- chlorophyll b

• chlorophyll a – abs blue-violet, red

~400-450, 650-700

• chlorophyll b & carotenoids – abs broadly blue-violet

450-500 & 600-650

• more wavelengths used for photosynthesis = more light energy absorbed

Photosynthesis – light absorption

If a car is red, which light wavelengths are reflected (NOT absorbed)?

Self-Check