key themes (2) “think like a biologist”: understand what life is. “unity” of life: what are...

Key Themes

(2) “Think Like a Biologist”: Understand What Life Is.“Unity” of life: What are common features of eukaryotes?

Energy conversions: Sugar breakdown & mitochondrial ATP formation

1

Lecture 7: Cellular Respiration

Yesterday’s Exit Ticket– Energy-releasing reactions:

• Large, complex smaller, simpler• Release energy and increase entropy

• e.g. ATP ADP and Pi

• e.g. respiration (glucose + O2 H2O + CO2 + ATP)

– Energy-requiring reactions:• Smaller, simpler large complex• Decrease entropy• e.g. ADP + Pi ATP

• e.g. photosynthesis (light E + H2O + CO2 glucose + O2)

Food-to-Energy

Fig. 9.1

Fig. 8.3

Respiration

3

Cellular respiration breaks down energy-rich molecules to CO2 & water, extracting their energy.

Fig. 9.2

Lightenergy

ECOSYSTEM

Photosynthesisin chloroplasts

CO2 + H2OCellular respiration

in mitochondria

Organicmolecules+ O2

ATP powers most cellular work

Heatenergy

ATP

High energy

Low energy

C-H bond

“burned” with O2

to H2O + CO2

4

Photosynthesis:

Respiration:

ATP

Since ATP is too unstable,

C-H bonds in sugars are used for energy storage.

Converts solar energy

to ATP and uses ATP to make sugars

Converts the energy of sugars back to ATP as needed.

Sugar [CH2O]x + O2CO2 + H20

ATPLight (energy)

H+ & e-

H+ & e-

5

What is the goal of cellular respiration?

• Food ATP• Release the energy in C-H bonds• Harness that energy to create ATP

6-C sugar

Glucose + O2

(6-C sugar) ATP + CO2 + H20(energy)

3-C sugars+ some ATP

CO2

+ some ATPH2O + ATP

H+ & e-

O2

H+ & e-

paraibaparadise.com

6

What is the goal of cellular respiration?

6-C sugar3-C sugars

+ some ATPCO2

+ some ATPH2O + ATP

H+ & e-

O2

H+ & e-

Step 1: Glycolysis

Step 2: Citric Acid

Cycle

Step 3: Oxidative

Phosphorylation

7

Step 1: Glycolysis•Occurs in: cytosol•Starts with: glucose, NAD+, ADP, Pi

•Produces: pyruvate, NADH, and ATP

Glucose (6-C sugar)

Pyruvates(3-C sugars)+ some ATP

H+ & e-

8

Cytosol

Fig. 9.6

Glucose Pyruvate

Glycolysis

Electronscarried off by NADH

ATPSome



9


Glucose (6-C sugar)



H+ & e-

NAD+

NADH

Glycolysis can occur with or without O2!!

10


CO2

+ some ATPH+ & e-

Step 2: Citric Acid Cycle•Occurs in: mitochondrial matrix (fluid space)•Starts with: pyruvate, NAD+, FAD, ADP, Pi

•Produces: NADH, FADH2, CO2 and ATP

11

Fig. 9.6

Mitochondrion

Electrons carried off by

NADH & FADH2

Citricacidcycle

ATP

Glucose Pyruvate

Glycolysis


Some ATPSome

Cytosol



12

CO2

+ some ATPH+ & e-



NAD+

FAD

NADHFADH2


13

Step 3: Oxidative Phosphorylation(Using oxygen to phosphorylate ADP)

•Occurs in: mitochondrial inner membranes•Starts with: O2, NADH, FADH2, ADP, Pi

•Produces: H2O, ATP, NAD+, FAD

H2O + ATP

NADH

O2

NADHFADH2

ADPPi

14

Electrontransport

andATP synthase

Mitochondrion

ATP


NADH & FADH2

Citricacidcycle

ATP

Glucose Pyruvate

Glycolysis


Fig. 9.6

Some Some ATPLots of

Cytosol

Step 3: Oxidative Phosphorylation(Using oxygen to phosphorylate ADP)

•Occurs in: mitochondrial inner membranes•Starts with: O2, NADH, FADH2, ADP, Pi

•Produces: H2O, ATP, NAD+, FAD

15

H (electrons and H+) removed from high energy C-H bonds

CO2

+ some ATPH2O + ATP

H+ & e- (via NADH)

O2


Glucose (6-C sugar)

H+ & e- (via NADH & FADH2)

16

I

H - C - OH (CHOH)6 (= C6H12O6 sugar)

I

to

O = C = O CO2

Where does H go?H (electrons and H+) are loaded onto

electron carriers NADH & FADH2


(all the way to CO2 in the citric acid cycle)

17


CO2

+ some ATPH2O + ATP

H+ & e- (via NADH)

O2


Glucose (6-C sugar)


18

ATP

Mitochondrion

ATP


NADH & FADH2

Citricacidcycle

ATP

Cytosol

Glucose Pyruvate

Glycolysis


Fig. 9.6

2 2 ~34

Most ATP is formed by electron transport chainthrough oxidative phosphorylation

Electrontransport

andATP synthase

19

Smooth outer membrane

Folded inner membrane:

Matrix:Citric acid cycle

Mitochondria

Electron transport chain & ATP formation

Fig. 6.17

20

Fig. 10.16

Potential energy (ion gradient) used for ATP formation

Fig.8.7

21

Protein complexof electroncarriers

H+

H+H+

Cyt c

Q

V

FADH2 FAD

NAD+NADH(carrying electronsfrom food)

Electron transport chain & pumping of protons

2 H+ + 1/2O2 H2O

ADP +Pi

H+

H+

ATP synthase

ATP

21

The electron transport chain pumps protons against the concentration gradient; builds up a high H+ concentration in intermembrane space.

Intermembranespace

Mitochondrial matrix

Innermembrane

Fig. 9.16

ATP synthesis via H+ flow

Step 3: Oxidative Phosphorylation

22

Smooth outer membrane

Folded inner membrane

Intermembrane space

MitochondriaFig. 6.17

Matrix

23

Protein complexof electroncarriers

H+

H+H+

Cyt c

Q

V

FADH2 FAD

NAD+NADH(carrying electronsfrom food)

Electron transport chain & pumping of protons

2 H+ + 1/2O2 H2O

ADP +Pi

H+

H+

ATP

21

Intermembranespace

Mitochondrial matrix

Innermembrane

Fig. 9.16

ATP synthesis via H+ flow

INTERMEMBRANE SPACE

RotorH+ Stator

Internalrod

Cata-lyticknob

ADP+

P ATPi

MITOCHONDRIAL MATRIX

Fig. 9.14Oxygen (O2) is the final electron (and H+) acceptor

ATP synthase

Protons flow downhill through the ATP synthase, driving phosphorylation of ADP to ATP.

Step 3: Oxidative Phosphorylation

24

Let’s take a look at the whole sequence: • Step 1: Glycolysis• Step 2: Citric Acid Cycle • Step 3: Oxidative Phosphorylation

http://www.colorado.edu/ebio/genbio/09_15ElectronTransport_A.html

25

Electron Donors and Electron Acceptors

CO2

+ some ATPH2O + ATP

H+ & e- (via NADH)

O2


Glucose (6-C sugar)


Original electron donor in cellular respiration

Electron donors for mitochondrial

electron transport chain

Electron acceptor from mitochondrial

electron transport chain

26

ATP links the energy from breakdown of energy-rich food molecules to cellular work

P iADP+

Energy frombreakdown ofenergy-rich molecules

Energy for cellularwork

ATP + H2OEnergy loaded onto

ATPEnergy released from

ATP

Fig. 8.12

27

Proteins

Proteins Carbohydrates

Aminoacids

Sugars

Fats

Glycerol Fattyacids

Glycolysis

Glucose

Glyceraldehyde-3-

Pyruvate

P

NH3

Acetyl CoA

Citricacidcycle

Oxidativephosphorylation

Fig. 9.20

The cellular respiration pathway for

Carbohydrates

Fats

28

Predict how the enzymes that function early in glycolysis, and start the breakdown of glucose, should be regulated: The enzymes should

A) not be regulated.B) be turned off when enough (ATP) energy is available.C) be turned on when more (ATP) energy is needed.D) be regulated in a dual way, both by activation when more ATP energy is needed and by inactivation when enough ATP energy is available.

29

5 min break

www.stthomasblog.com

30

Key Themes

Energy conversions: Sugar breakdown without oxygen

via glycolysis + fermentation

31

Glucose

Glycolysis

PyruvateCYTOSOL

MITOCHONDRION

Fig. 9.19

• Step 1 of cellular respiration:

Glycolysisoutside

mitochondria

From glucose (6 C) to 2

pyruvate (3 C)Citricacidcycle

32

Glucose

Glycolysis

PyruvateCYTOSOL

O2 present:

Aerobic cellular respiration

MITOCHONDRION

Acetyl CoA

Citricacidcycle

Fig. 9.19

•Only when oxygen is present

can glucosebe broken

down completely

in the mitochondria

for high energy yield

33

Glucose

Glycolysis

PyruvateCYTOSOL

No O2 present:Fermentation

MITOCHONDRION

Acetyl CoAEthanolor

lactateCitricacidcycle

Fig. 9.19 34

Alcoholic fermentation (forms ethanol plus CO2) by yeasts and bacteria under anaerobic conditions

Glycolysis & fermentation

2 ADP + 2 P i 2 ATP

Glucose Glycolysis

2 Pyruvate

2 NADH2 NAD+

+ 2 H+CO2

2 Acetaldehyde2 Ethanol

(a) Alcohol fermentation

2

Fig. 9.18

The solution when oxygen runs out or is unavailable (anaerobic conditions):

35

Glycolysis and fermentation Fermentation to ethanol

2 ADP + 2Pi 2 ATP

Glucose Glycolysis

2 Pyruvate

2 NADH2 NAD+

+ 2 H+CO2

2 Acetaldehyde2 Ethanol(a) Alcohol fermentation

2

Fig. 9.18(a)

Yeasts use alcoholic fermentation to convert hexoses (from sugar cane sucrose or corn starch or

cellulose) into ethanol for fuels

Production of Foods & Fuels

36

Alcohol fermentation (forms ethanol plus CO2)• Yeasts & bacteria• Anaerobic conditions

Glycolysis & fermentation

2 ADP + 2 P i 2 ATP

Glucose Glycolysis

2 Pyruvate

2 NADH2 NAD+

+ 2 H+CO2



2

Fig. 9.18

Do all organisms use alcohol fermentation when oxygen is in

short supply?37

Alcohol fermentation (forms ethanol plus CO2)• Yeasts & bacteria• Anaerobic conditions

Glycolysis & fermentation without oxygen (anaerobic

conditions)

2 ADP + 2 P i 2 ATP

Glucose Glycolysis

2 Pyruvate

2 NADH2 NAD+

+ 2 H+CO2



2

Glucose

2 ADP + 2 Pi 2 ATP

Glycolysis

2 NAD+ 2 NADH

+ 2 H+

2 Pyruvate

2 Lactate

(b) Lactic acid fermentation

Fig. 9.18

Lactic acid fermentation • Other fungi & bacteria • Also in muscle cells under anaerobic conditions

38

Production of Foods and Fuels by Microbes in home & industryYeasts for beer & wine [alcohol fermentation] & for bread leavening [from the CO2 gas formed]; lactic acid bacteria for fermented products from milk or other foods[lactic acid fermentation].

http://www.bact.wisc.edu/themicrobialworld/Effects.html39

Fermentation versus aerobic respiration

Different human muscle fibers use different metabolism (See also Table 49.1):

Glucose

Glycolysis

Pyruvate

CYTOSOL

Fermentation


MITOCHONDRION

Acetyl CoALactate

Citricacidcycle

Fig. 9.1940



Glucose

Glycolysis

Pyruvate

CYTOSOL

Fermentation


MITOCHONDRION

Acetyl CoALactate

Citricacidcycle

Fig. 9.19

• Fast-twitch glycolytic fibers (for sprint) use glycolysis - quick, but does not provide much energy.

Glycogen

41



[Glucose]

Glycolysis

Pyruvate

CYTOSOL

Fermentation


MITOCHONDRION

Acetyl CoALactate

Citricacidcycle

Fig. 9.19

• Fast-twitch glycolytic fibers (for sprint) use glycolysis - quick, but does not provide much energy.

• Slow-twitch oxidative fibers (with many mitochondria for extended exercise) use oxidative respiration -slower, but yields much more energy.

Fats

42

Glucose

Glycolysis

PyruvateCYTOSOL

No O2 present:Fermentation

O2 present:


MITOCHONDRION

Acetyl CoAEthanolor

lactateCitricacidcycle

Fig. 9.19

Fermentation in absence

of O2

Aerobic respiration in

presence of O2

43

Fig. 9.544

Hank’s Crash Course in Cellular Respiration

3:30-end

http://www.youtube.com/watch?v=00jbG_cfGuQ&feature=relmfu

45

Today’s Exit Ticket

Glucose

Process:

Location:

# ATPs:

Process:

Location:Products Released:

Location:Products Released:

# ATPs:

# ATPs:

Process:

46

key themes (2) “think like a biologist”: understand what life is. “unity” of life: what are...

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