CELLULAR RESPIRATION · Photosynthesis •The sun is the main source of energy for life. •The process of converting light energy into chemical energy is called photosynthesis. carbon

CELLULAR RESPIRATION CELLS AS THE BASIS OF LIFE

Eukaryotic Cell Organisation

PLANT CELL ANIMAL CELL

All Cells Require Energy

• All living cells use energy for movement, synthesis

and maintenance of a stable intracellular

environment.

• Law of Conservation of Energy: energy cannot

be created or destroyed, but simply changed from

one form to another

• Forms of energy: light, heat, chemical, kinetic

Living cells must be able to convert chemical

energy into other forms of energy which are more

useful to the cell

Photosynthesis

• The sun is the main source of energy for life.

• The process of converting light energy into

chemical energy is called photosynthesis.

carbon dioxide + water glucose + oxygen

6CO2 + 6H2O C6H12O6 + 6O2

light

chlorophyll

light

chlorophyll

Photosynthesis

• Photosynthesis occurs in the chloroplasts

– Chloroplasts contain the green pigment chlorophyll

– Light energy is trapped by chlorophyll

Photosynthesis

• Chloroplasts are found in cells called mesophyll cells which

are found in the leaves.

Photosynthesis

• Stomata are located on the under side of a leaf. They consist of

two guard cells surrounding a small pore.

• The guard cells have a very thick cell wall. Water is able to move in

and out of the guard cells, causing them to change shape.

– Turgid (swollen) guard cells = stomata open

– Flaccid (shrunken) guard cells = stomata close

Photosynthesis

FLACCID GUARD CELLS

• Occurs during times of water stress (limited availability or in

warmer air temperatures)

• Causes stomata to close

• Generally occurs during the day

• Reduces water loss

• Oxygen and carbon dioxide does not diffuse into and out of

the leaf

TURGID GUARD CELLS

• Occurs when water is available (particularly in cooler air

temperatures)

• Causes stomata to open

• Generally occurs during the night

• Oxygen and carbon dioxide readily diffuse into and out of

the leaf

Photosynthesis

During the night, cooler

air temperatures

(moisture in the air)

allow guard cells to

swell, opening the

stomata

Open stomata allow

carbon dioxide in the air

to enter the leaf and

oxygen (produced by

photosynthesis) to exit

the leaf During the day, warmer

air temperatures (less

moisture in the air)

cause guard cells to

become flaccid, closing

the stomata

Sunlight shining on the

leaves gets captured by

the green pigment

chlorophyll (found in

the chloroplasts)

The captured energy

allows carbon dioxide

and water to combine

to form glucose and

oxygen

Cellular Respiration

• Photosynthesis involves converting light energy

into chemical energy (in the form of glucose).

• The chemical energy must then be

transformed into a useable form of energy.

carbon dioxide + water glucose + oxygen

6CO2 + 6H2O C6H12O6 + 6O2

light

chlorophyll

light

chlorophyll


• Energy is stored in chemical bonds between atoms in

molecules. The more chemical bonds, the more energy

that the molecule contains.

BREAKING BONDS Energy is released

MAKING BONDS Energy is required


• Glucose is a complex macromolecule that

contains many bonds. These bonds can be

broken to create smaller molecules with less

energy.

• This processes is called cellular respiration.

• As large molecules are broken down into small

molecules some of the stored chemical energy is

converted to energy in chemical bonds of a

small molecule called ATP and the rest is

released as heat.

ATP, ADP and Pi

• ATP = adenosine tri-phosphate

• ATP is the cell’s immediate source of energy. It

is used for almost every energy-requiring

reaction in a cell

ADENINE BASE

5-CARBON

(PENTOSE) SUGAR

THREE

PHOSPHATE

GROUPS

ATP, ADP and Pi

• ATP = adenosine tri-phosphate

• ATP is the cell’s immediate source of energy. It

is used for almost every energy-requiring

reaction in a cell

ADENINE BASE

5-CARBON

(PENTOSE) SUGAR

THREE

PHOSPHATE

GROUPS

This bond can be easily

broken to release free

energy

ATP, ADP and Pi

• When the weak phosphate bond is broken, ATP

is converted to ADP (adenosine di-phosphate)

and phosphate. Free energy becomes available.

+

ATP ADP PHOSPHATE

ATP, ADP and Pi

• Cells use ATP continuously, however ATP stores

can be regenerated when energy from

respiration reactions is used to reform ATP from

ADP and phosphate.

ATP, ADP and Pi

BREAKING BONDS Energy is released

MAKING BONDS Energy is required

ATP ADP + P ATP ADP + P

Aerobic Respiration

Glucose C6H12O6

(from photosynthesis)

Aerobic Respiration

Glycolysis

↓

Citric Acid Cycle

↓

Electron Transport Chain

Anaerobic Respiration

Glycolysis

↓

Fermentation

… is broken down to release energy via …

Aerobic Respiration

• The food we eat reacts with the air we breathe to

produce smaller molecules and energy which is

needed for life.

• Cells extract energy from glucose by breaking

bonds between the carbon atoms, producing

ATP.

Aerobic respiration ONLY occurs in the

presence of oxygen

glucose + oxygen carbon dioxide + water + energy

C6H12O6 + 6O2 6CO2 + 6H2O + energy

Glycolysis

• Glucose (6 carbons) is broken in half forming

two, 3 carbon molecules called pyruvate.

• Occurs in the cytoplasm of cells.

• 2 ATP molecules are produced.

PYRUVATE

(3 carbons)

GLUCOSE

(6 carbons)

2 x ATP

Citric Acid Cycle

• Pyruvate moves to the mitochondrial matrix,

which is where the citric acid cycle occurs.

• The carbon bonds in pyruvate are broken,

forming new, small energy carriers as products.

PYRUVATE

(3 carbons)

CARBON DIOXIDE (waste product)

NEW SMALL

ENERGY CARRIERS

CITRIC ACID

CYCLE


• The electron transport chain is located in the

mitochondria inner membrane.

• It is simply a chain reaction of events that leads

to the production of ATP.

• The small energy carrier products from the citric

acid cycle power the electron transport chain.

• 36 ATP molecules are produced

WATER (from O2 and H+)

NEW SMALL

ENERGY CARRIERS

(from citric acid cycle)

ELECTRON TRANSPORT

CHAIN

36 x ATP

Aerobic Respiration Summary

C6H12O6 + 6O2 6CO2 + 6H2O + 38 ATP

GLYCOLYSIS

Glucose (from photosynthesis) is broken down into 2x pyruvate.

2 ATP molecules produced.

CITRIC ACID CYCLE

Pyruvate is broken down to produce carbon dioxide and new small

energy carriers.

ELECTRON TRANSPORT CHAIN

Small energy carriers (from Citric Acid Cycle) power the electron

transport chain to produce 36 ATP molecules and water.


C6H12O6 + 6O2 6CO2 + 6H2O + 38 ATP

GLYCOLYSIS



CITRIC ACID CYCLE


energy carriers.





C6H12O6 + 6O2 6CO2 + 6H2O + 38 ATP

GLYCOLYSIS



CITRIC ACID CYCLE


energy carriers.





C6H12O6 + 6O2 6CO2 + 6H2O + 38 ATP

GLYCOLYSIS



CITRIC ACID CYCLE


energy carriers.





C6H12O6 + 6O2 6CO2 + 6H2O + 38 ATP

GLYCOLYSIS



CITRIC ACID CYCLE


energy carriers.





C6H12O6 + 6O2 6CO2 + 6H2O + 38 ATP

GLYCOLYSIS



CITRIC ACID CYCLE


energy carriers.





Glucose C6H12O6

(from photosynthesis)

Aerobic Respiration

Glycolysis

↓

Citric Acid Cycle

↓



Glycolysis

↓

Fermentation

Broken down to release energy via …


• When oxygen is NOT available, conditions are

considered ‘anaerobic’.

• In the absence of oxygen, glucose is only partly

broken down, the molecules produced are larger

and there will be less energy available to the cell.

• The first step is glycolysis. Since glycolysis does

not require oxygen, is occurs the same as it does

for aerobic respiration

Fermentation

Plants and Yeast

glucose ethanol + carbon dioxide + energy

C6H12O6 2C2H5OH + 2CO2 + energy

Animals

glucose lactic acid + energy

C6H12O6 2C3H6O3 + energy

Fermentation – Plants and Yeast

• In the absence of oxygen, plants and yeast

undergo fermentation to form ethanol and

carbon dioxide.

• 2 ATP molecules are formed during glycolysis

PYRUVATE

(from glycolysis)

CARBON DIOXIDE (waste product)

ETHANOL

FERMENTATION

Fermentation – Animals

• In the absence of oxygen, animals undergo

fermentation to form lactic acid.

• 2 ATP molecules are formed during glycolysis

PYRUVATE

(from glycolysis) LACTIC ACID

FERMENTATION

Anaerobic Respiration Summary

PLANTS AND YEAST

C6H12O6 2C2H5OH + 2CO2 + 2 ATP

GLYCOLYSIS Glucose (from photosynthesis) is broken down into 2x pyruvate.


FERMENTATION Pyruvate is broken down to produce ethanol and carbon dioxide.


PLANTS AND YEAST






PLANTS AND YEAST






PLANTS AND YEAST






ANIMALS

C6H12O6 2C3H6O3 + 2 ATP



FERMENTATION Pyruvate is broken down to produce lactic acid.


ANIMALS

C6H12O6 2C3H6O3 + 2 ATP





ANIMALS

C6H12O6 2C3H6O3 + 2 ATP





ANIMALS

C6H12O6 2C3H6O3 + 2 ATP




Cellular Respiration Summary

PHOTOSYNTHESIS Production of glucose

AEROBIC RESPIRATION

GLYCOLYSIS Glucose → Pyruvate

CITRIC ACID CYCLE Production of carbon dioxide

and new small energy carriers

ELECTON TRANSPORT CHAIN Production of ATP and water

FERMENTATION Plants/Yeast –

Production of ethanol

and carbon dioxide

FERMENTATION Animals – production

of lactic acid

ANAEROBIC RESPIRATION

2 x ATP

36 x ATP

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CELLULAR RESPIRATION · Photosynthesis •The sun is the main source of energy for life. •The process of converting light energy into chemical energy is called photosynthesis. carbon