Lecture 3 Outline (Ch. 9, 10)

I. Recap of Glycolysis, Coenzyme Junction

II. Cellular Respiration continued

A. Citric Acid Cycle (aka Krebs/TCA cycle)

B. Electron Transport Chain (ETC)

C. Chemiosmosis

III. Anaerobic respiration

IV. Respiration using other biomolecules

V. Introduction to Photosynthesis

A. Chloroplasts

B. Light wavelengths

VI. Preparation for next lecture

Steps of Respiration

Steps of Respiration

• Stages of respiration:

2. Citric acid cycle

Mitochondrial matrix

e- transfer: redox

Cellular Respiration

2. Citric acid cycle

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

• few ATP so far

• e- to carriers

(NAD+, FAD)

• now in mitochondrial matrix

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

• 2 ATP made

-inputs:

4 CO2

(H2O = none)

-outputs:

2 Acetyl CoA (2C)

2 ATP

6 NADH

2 FADH2

[2 oxaloacetate (4C)]

Where do outputs go?

Citric acid cycle

Which step so far has loaded the most electron carriers?

A. Glycolysis

B. Coenzyme junction

C. Citric acid cycle

D. They are all equal so far

E. No electron carriers have been loaded yet

Steps of Respiration

• Stages of respiration:

3. ETC

Proton Motive Force

Cellular Respiration

3. Electron transport chain (ETC)

• lots of energy harvested

• released in stages

• so far, 4 ATP – made by substrate phosphorylation – not as efficient

• now, many ATP – made by oxidative phosphorylationoxidative phosphorylation

Steps of Respiration

• Stages of respiration:

4. Chemiosmosis

ATP produced!

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

4. Chemiosmosis

• H+ must enter matrix here

• Generates 1 ATP per ~3.4 H+

Where is the electron transport chain located in the diagram?

A. Green area

B. Blue area

C. Yellow area

D. Pink area

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-

• ethanol produced

• brewing & baking

Cellular Respiration - anaerobic

• pyruvate accepts e-

• lactate produced

• Types of fermentation -

2. Lactic acid

• muscle fatigue

Cellular Respiration

• Comparison of aerobic vs. anaerobic respiration:

• e- carriers loaded:

• ATP per glucose:

Aerobic Anaerobic

• initial e- acceptor:

• final e- acceptor:

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 (2H2O) 2 net 2 NADH

Coenzyme Junction

Citric Acid Cycle

Electron Transport Chain

Oxidative phosphorylation

Fermentation

Which cells perform aerobic cellular respiration?

A. Plant cells only

B. Animal cells only

C. Bacteria only

D. Plant and animal cells

E. Plant, animal and bacterial cells

Photosynthesis - overview

Overall purpose:

Photosynthesis - overview

• photosynthesis:

light chemical energy

• complements respiration

- light rxn: solar energy harvest

- “dark” rxn: energy to organics

Cellular Respiration:(Exergonic)

Photosynthesis:(Endergonic)

Cellular Respiration vs. Photosynthesis

chloroplast recap

Outer membrane

Inner membrane

Thylakoid membrane

Intermembrane space

Stroma

Thylakoid space

Photosynthesis - overview

• Photosynthesis -

1. light rxn: store energy & split water

NADPH & ATP given off

Chloroplast model:

Redox Reactions

Equation for photosynthesis

CO2 + H2O + light energy C6H12O6 + O2

photo synthesis

In photosynthesis, which of the following happens to H2O?

A. Oxidized to oxygen gas

B. Reduced to oxygen gas

C. Oxidized to glucose

D. Reduced to glucose

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)?

A. Green (500-550 nm)B. Red (650-700 nm)C. Blue (450-500 nm)D. All wavelengths are reflectedE. All wavelengths absorbed

Things To Do After Lecture 3…Reading and Preparation:

1. Re-read today’s lecture, highlight all vocabulary you do not understand, and look up terms.

2. Read chapter 9, focus on material covered in lecture (terms, concepts, and figures!)

3. Ch. 9 Self-Quiz: 1-7 (correct using the back of the book).

4. Skim next lecture.

“HOMEWORK”:

1. Draw a diagram similar to the cell on the next slide, and show where each step of cellular respiration occurs.

2. Match up the three boxes each for the citric acid cycle and oxidative phosphorylation (from last lecture).

3. Compare and contrast aerobic respiration and fermentation for three things that are similar/shared AND three things that are different!

4. Diagram a chloroplast labeling the three membranes and three spaces.

5. In the spectrum of visible light (380 to 750 nm), indicate which wavelengths (number AND color) are absorbed by chloroplasts and which are not absorbed.

Self-Check