Cellular Respiration

Cellular Respiration

Honors Biology

Honors Biology

What is Cellular Respiration?

What is Cellular Respiration?

The process of converting food energy

The process of converting food energy

into ATP energy

into ATP energy

C

C

6

6

H

H

12

12

O

O

6

6

+ 6 O

+ 6 O

2

2

→

→

6 CO

6 CO

2

2

+ 6 H

+ 6 H

2

2

O + 36 ATP

O + 36 ATP

Why are both Photosynthesis and

Why are both Photosynthesis and

Cell Respiration important to

Cell Respiration important to

Ecosystems?

Ecosystems?

Light is the ultimate

Light is the ultimate

source of energy for all

source of energy for all

ecosystems

ecosystems

Chemicals cycle and

Chemicals cycle and

Energy flows

Energy flows

Photosynthesis and

Photosynthesis and

cellular respiration are

cellular respiration are

opposite reactions

opposite reactions

Why do plants need both

Why do plants need both

chloroplasts and mitochondria?

chloroplasts and mitochondria?

Chloroplasts use

Chloroplasts use

energy from the

energy from the

sun to make

sun to make

glucose

glucose

Mitochondria

Mitochondria

convert glucose to

convert glucose to

ATP—the energy

ATP—the energy

currency of the cell

currency of the cell

What is ATP?

What is ATP?

Adenosine Triphosphate

Adenosine Triphosphate

–

5-Carbon sugar (Ribose)

5-Carbon sugar (Ribose)

–

Nitrogenous base (Adenine)

Nitrogenous base (Adenine)

–

3 Phosphate groups

3 Phosphate groups

Energy currency of the

Energy currency of the

cell

cell

The chemical bonds that

The chemical bonds that

link the phosphate groups

link the phosphate groups

together are high energy

together are high energy

bonds

bonds

When a phosphate group

When a phosphate group

is removed to form ADP

is removed to form ADP

and P, small packets of

and P, small packets of

energy are released

energy are released

How is ATP used?

How is ATP used?

As ATP is broken down, it

As ATP is broken down, it

gives off usable energy to

gives off usable energy to

power chemical work and

power chemical work and

gives off some nonusable

gives off some nonusable

energy as heat.

energy as heat.

Synthesizing molecules for

Synthesizing molecules for

growth and reproduction

growth and reproduction

Transport work – active

Transport work – active

transport, endocytosis, and

transport, endocytosis, and

exocytosis

exocytosis

Mechanical work – muscle

Mechanical work – muscle

contraction, cilia and flagella

contraction, cilia and flagella

movement, organelle

movement, organelle

movement

movement

Why use ATP energy and not

Why use ATP energy and not

energy from glucose?

energy from glucose?

Breaking down glucose yields too much energy

Breaking down glucose yields too much energy

for cellular reactions and most of the energy

for cellular reactions and most of the energy

would be wasted as heat.

would be wasted as heat.

1 Glucose = 686 kcal

1 Glucose = 686 kcal

1 ATP = 7.3 kcal

1 ATP = 7.3 kcal

1 Glucose

1 Glucose

→

→

36 ATP

36 ATP

How efficient are cells at converting glucose into

How efficient are cells at converting glucose into

ATP?

ATP?

–

38% of the energy from glucose yields

38% of the energy from glucose yields

ATP, therefore 62% wasted as heat.

ATP, therefore 62% wasted as heat.

Cellular Respiration is a Redox

Cellular Respiration is a Redox

Reaction

Reaction

C

C

6

6

H

H

12

12

O

O

6

6

+ 6 O

+ 6 O

2

2

→ 6 CO

→ 6 CO

2

2

+ 6 H

+ 6 H

2

2

O

O

Oxidation

Oxidation

is the loss of electrons or H

is the loss of electrons or H

+

+

Reduction

Reduction

is the gain of electrons or H

is the gain of electrons or H

+

+

Glucose is oxidized when electrons and H

Glucose is oxidized when electrons and H

+

+

are passed to coenzymes NAD

are passed to coenzymes NAD

+

+

and FAD

and FAD

before reducing or passing them to oxygen.

before reducing or passing them to oxygen.

Glucose is oxidized by a

Glucose is oxidized by a

series of smaller

series of smaller

steps

steps

so that smaller packets of energy are

so that smaller packets of energy are

released to make ATP, rather than one large

released to make ATP, rather than one large

explosion of energy.

explosion of energy.

(Oxidation)

(Reduction)

Cell Respiration can be divided into 4

Cell Respiration can be divided into 4

Parts:

Parts:

1) Glycolysis

1) Glycolysis

2) Oxidation of Pyruvate / Transition Reaction

2) Oxidation of Pyruvate / Transition Reaction

3) The Krebs Cycle

3) The Krebs Cycle

4) The Electron Transport Chain and

4) The Electron Transport Chain and

Chemiosmotic Phosphorylation

Chemiosmotic Phosphorylation

Where do the 4 parts of

Where do the 4 parts of

Cellular Respiration take place?

Cellular Respiration take place?

Glycolysis:

Glycolysis:

–

Cytosol

Cytosol

Oxidation of

Oxidation of

Pyruvate:

Pyruvate:

–

Matrix

Matrix

The Krebs Cycled:

The Krebs Cycled:

–

Matrix

Matrix

Electron Transport

Electron Transport

Chain and

Chain and

Cheimiosmotic

Cheimiosmotic

Phosphorylation:

Phosphorylation:

–

Cristae

Cristae

Parts of the Mitochondria

Parts of the Mitochondria

Anaerobic Respiration (no oxygen required, cytoplasm)

Anaerobic Respiration (no oxygen required, cytoplasm)

1. Glycolysis
(substrate level)

Glucose



4 ATP (Net 2 ATP)

2 ATP

2 NADH
2 Pyruvate

Aerobic Respiration (oxygen required, mitochondria)

Aerobic Respiration (oxygen required, mitochondria)

2. Oxidation

of
Pyruvate

2 Pyruvate



2 CO

2

2 NADH
2 Acetyl CoA

1. Krebs Cycle
(substrate level)

2 Acetyl CoA



4 CO

2

2 ATP
6 NADH
2 FADH

2

1. Electron

Transport
Chain

(chemiosmotic)

10 NADH



32 ATP

2 FADH

2

6 H

2

O

6 O

2

Total: 36 ATP produced

ATP is made in two ways:

ATP is made in two ways:

1)

1)

Substrate Level

Substrate Level

Phosphorylation

Phosphorylation

(glycolysis

(glycolysis

& Krebs cycle)

& Krebs cycle)

2)

2)

Chemiosmotic

Chemiosmotic

Phosphorylation

Phosphorylation

(electron

(electron

transport chain)

transport chain)

Substrate-Level

Substrate-Level

Phosphorylation:

Phosphorylation:

Energy and phosphate are

Energy and phosphate are

transferred to ADP using an

transferred to ADP using an

enzyme, to form ATP.

enzyme, to form ATP.

Phosphate comes from one

Phosphate comes from one

of the intermediate

of the intermediate

molecules produced from

molecules produced from

the breakdown of glucose.

the breakdown of glucose.

Glycolysis

Glycolysis

Glucose (C

Glucose (C

6

6

) is split to make

) is split to make

2 Pyruvates (C

2 Pyruvates (C

3

3

)

)

–

1

1

st

st

: ATP energy used to phosphorylate

: ATP energy used to phosphorylate

glucose (stored energy)

glucose (stored energy)

–

2

2

nd

nd

: phosphorylated glucose broken down

: phosphorylated glucose broken down

into two C

into two C

3

3

sugar phosphates

sugar phosphates

–

3

3

rd

rd

: the sugar phosphates are oxidized to

: the sugar phosphates are oxidized to

yield electrons and H

yield electrons and H

+

+

ions which are

ions which are

donated to 2 NAD

donated to 2 NAD

+

+

→

→

2 NADH (stored

2 NADH (stored

electron and hydrogen for the Electron

electron and hydrogen for the Electron

Transport Chain)

Transport Chain)

–

4

4

th

th

: The energy from oxidation is used to

: The energy from oxidation is used to

make 4 ATP molecules (net 2 ATP)

make 4 ATP molecules (net 2 ATP)

This is substrate level phosphorylation

This is substrate level phosphorylation

because an enzyme transfers

because an enzyme transfers

phosphate to ADP making ATP

phosphate to ADP making ATP

Glycolysis produces very little ATP

Glycolysis produces very little ATP

energy, most energy is still stored in

energy, most energy is still stored in

Pyruvate molecules.

Pyruvate molecules.

Glucose 

2 Pyruvate

2 ATP

4 ATP (Net 2 ATP)
2 NADH

Oxidation of Pyruvate /Transition

Oxidation of Pyruvate /Transition

Reaction

Reaction

When Oxygen is present,

2 Pyruvates go to the

matrix where they are

converted into 2 Acetyl

CoA (C

2

).

Multienzyme complex:

– 1

st:

each Pyruvate releases

CO

2

to form Acetate.

– 2

nd:

Acetate is oxidized and

gives electrons and H

+

ions

to 2 NAD

+

→ 2 NADH.

– 3

rd

Acetate is combined with

Coenzyme A to produce 2

Acetyl CoA molecules.

2 NADH’s carry electrons

and hydrogens to the

Electron Transport Chain.

2 Pyruvate



2 CO

2

2 NADH
2 Acetyl CoA

The Krebs Cycle / Citric Acid

The Krebs Cycle / Citric Acid

Cycle

Cycle

8 Enzymatic Steps in Matrix of Mitochondria:

Break down and Oxidize each Acetyl

CoA (2-C’s) to release 2 CO

2

and yield

electrons and H

+

ions to 3 NAD

+

+

1 FAD → 3 NADH + FADH

2

. This yields

energy to produce ATP by substrate level

phosphorylation.

The first step of the Krebs cycle combines

Oxaloacetate (4 C’s) with Acetyl CoA to

form Citric Acid, then the remaining 7

steps ultimately recycle oxalacetate.

Two Turns of the Krebs Cycle are required to

break down both Acetyl Coenzyme A

molecules.

The Krebs cycle produces some chemical

energy in the form of ATP but most of the

chemical energy is in the form of NADH

and FADH

2

which then go on to the

Electron Transport Chain.

2 Acetyl CoA



4 CO

2

2 ATP
6 NADH
2 FADH

2

The Electron Transport Chain

The Electron Transport Chain

NADH and FADH

NADH and FADH

2

2

produced

produced

earlier, go to the Electron

earlier, go to the Electron

Transport Chain.

Transport Chain.

NADH and FADH

NADH and FADH

2

2

release

release

electrons to carriers/proteins

electrons to carriers/proteins

embedded in the membrane

embedded in the membrane

of the cristae. As the

of the cristae. As the

electrons are transferred, H

electrons are transferred, H

+

+

ions are pumped from the

ions are pumped from the

matrix to the intermembrane

matrix to the intermembrane

space up the concentration

space up the concentration

gradient. Electrons are

gradient. Electrons are

passed along a series of 9

passed along a series of 9

carriers until they are

carriers until they are

ultimately donated to an

ultimately donated to an

Oxygen molecule.

Oxygen molecule.

½ O

½ O

2

2

+ 2 electrons + 2 H

+ 2 electrons + 2 H

+

+

(from NADH and FADH

(from NADH and FADH

2

2

)

)

→

→

H

H

2

2

O.

O.

10 NADH



32 ATP

2 FADH

2

H

2

O

Oxygen

http://vcell.ndsu.nodak.edu/animations/etc/movie.htm

Chemiosmotic Phosphorylation

Chemiosmotic Phosphorylation

Hydrogen ions travel down their concentration gradient through a channel

Hydrogen ions travel down their concentration gradient through a channel

protein coupled with an enzyme called

protein coupled with an enzyme called

ATP Synthase

ATP Synthase

.

.

As H

As H

+

+

ions move into the matrix, energy is released and used to combine

ions move into the matrix, energy is released and used to combine

ADP + P

ADP + P

→

→

ATP.

ATP.

Hydrogens are recycled and pumped back across the cristae using the

Hydrogens are recycled and pumped back across the cristae using the

Electron Transport Chain.

Electron Transport Chain.

ATP diffuses out of the mitochondria through channel proteins to be used

ATP diffuses out of the mitochondria through channel proteins to be used

by the cell.

by the cell.

http://vcell.ndsu.nodak.edu/animations/atpgradient/movie.htm

ATP Synthase

ATP Synthase

Multisubunit complex

Multisubunit complex

with 4 parts:

with 4 parts:

–

Rotor

Rotor

– spins as H

– spins as H

+

+

ions flow

ions flow

–

Stator

Stator

– holds the rotor and

– holds the rotor and

knob complex together in the

knob complex together in the

cristae

cristae

–

Internal Rod

Internal Rod

– extends

– extends

between rotor and knob, spins

between rotor and knob, spins

when rotor spins which then

when rotor spins which then

turns the knob

turns the knob

–

Knob

Knob

– contains 3 catalytic

– contains 3 catalytic

sites that when turned change

sites that when turned change

shape and activate the enzyme

shape and activate the enzyme

used to make ATP

used to make ATP

Review ATP Production:

Review ATP Production:

1) Glycolysis

1) Glycolysis

→

→

2 ATP

2 ATP

2) Oxidation of Pyruvate

2) Oxidation of Pyruvate

→

→

No ATP

No ATP

3) The Krebs Cycle

3) The Krebs Cycle

→

→

2 ATP

2 ATP

4) The Electron Transport Chain and

4) The Electron Transport Chain and

Chemiosmotic Phosphorylation:

Chemiosmotic Phosphorylation:

–

Each NADH produces 2-3 ATP so 10

Each NADH produces 2-3 ATP so 10

NADH

NADH

→

→

28 ATP

28 ATP

–

Each FADH

Each FADH

2

2

produces 2 ATP so 2

produces 2 ATP so 2

FADH

FADH

2

2

→

→

4 ATP

4 ATP

Total = 36 ATP

Total = 36 ATP

1 Glucose = 686 kcal

1 Glucose = 686 kcal

1 ATP = 7.3 kcal

1 ATP = 7.3 kcal

1 Glucose

1 Glucose

→

→

36 ATP

36 ATP

How efficient are cells at converting

How efficient are cells at converting

glucose into ATP?

glucose into ATP?

–

38% of the energy from glucose

38% of the energy from glucose

yields ATP, therefore 62% wasted as

yields ATP, therefore 62% wasted as

heat (used to maintain body

heat (used to maintain body

temperature or is dissipated)

temperature or is dissipated)

–

Ex. Most efficient Cars: only 25% of

Ex. Most efficient Cars: only 25% of

the energy from gasoline is used to

the energy from gasoline is used to

move the car, 75% heat.

move the car, 75% heat.

All Types of Molecules can be

All Types of Molecules can be

used to form ATP by Cell

used to form ATP by Cell

Respiration:

Respiration:

Proteins, Carbohydrates,

Proteins, Carbohydrates,

and Lipids must first be

and Lipids must first be

broken down into their

broken down into their

monomers and absorbed

monomers and absorbed

in the small intestine.

in the small intestine.

Monomers may be

Monomers may be

further broken down into

further broken down into

intermediate molecules

intermediate molecules

before entering different

before entering different

parts of Cell respiration

parts of Cell respiration

to ultimately form ATP.

to ultimately form ATP.

Anaerobic Respiration:

Anaerobic Respiration:

Fermentation

Fermentation

If there is NO oxygen, then cells can make ATP by

If there is NO oxygen, then cells can make ATP by

Fermentation

Fermentation

Without oxygen, Oxidation of Pyruvate and the Electron Transport

Without oxygen, Oxidation of Pyruvate and the Electron Transport

Chain do not operate.

Chain do not operate.

Glucose

Glucose

→

→

Pyruvate

Pyruvate

→

→

Lactate

Lactate

NAD

NAD

+

+

Glycolysis

Glycolysis

2 NADH

2 NADH

Reduction Rxn

Reduction Rxn

or

or

2 ATP

2 ATP

Alcohol + CO

Alcohol + CO

2

2

Fermentation yields a net gain of 2 ATP by substrate level phosphorylation

Fermentation yields a net gain of 2 ATP by substrate level phosphorylation

for every 1 Glucose. (Inefficient)

for every 1 Glucose. (Inefficient)

Two Forms of Fermentation

Two Forms of Fermentation

:

:

Lactic Acid Fermentation (animals)

Lactic Acid Fermentation (animals)

Alcohol Fermentation (yeast)

Alcohol Fermentation (yeast)