CELL PROCESSES

CHAPTER 7

PHOTOSYNTHESIS

photo=light synthesis=forming

the process by which a plant uses the energy from the

light of the sun to make its own food.

OXYGEN PRODUCTION

Marine algae make 70-80% of the oxygen we breathe!

TWO PHASES OF PHOTOSYNTHESIS

1. Light-dependent phase

Involves capturing energy from sunlight.

2. Light-independent phase

Involves changing that energy into a form that an organism can use (glucose).

These two phases take place in different parts of a cell’s chloroplast.

IMPORTANT CHEMICAL PAIRS IN PHOTOSYNTHESIS

ADP/ATP

When ATP is produced, energy is stored.

When ADP is produced, energy is released.

NADP+/NADPH

NADP+ is like an electron shuttle that binds with

hydrogen ions and takes up electrons.

Water enters the roots

of plants.

Carbon dioxide enters

through tiny openings

on the undersides of the

leaves called stomata.

As a byproduct of

photosynthesis, stomata

also release the oxygen

we breathe.6

LIGHT-DEPENDENT PHASE

LIGHT-DEPENDENT PHASE

Sunlight enters the chloroplasts in

plant cells, passing through the

clear fluid in the chloroplasts

called the stroma.

In the interior of the chloroplasts

are grana, stacks of green sacks

called thylakoids.

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CHLOROPHYLL

Thylakoid membranes contain

chlorophyll embedded in strategic

places.

Chlorophyll is a pigment that absorbs

energy from sunlight to produce its

green color.

It uses sunlight to energize electrons,

which kickstart photosynthesis.

LIGHT-DEPENDENT PHASE- ELECTRON TRANSPORT CHAIN

Water molecules are split, forming oxygen, hydrogen ions and free electrons

Energized electrons pass through the electron transport chain

ATP synthase makes ATP from ADP

NADPH is generated

LIGHT-INDEPENDENT PHASE: THE CALVIN CYCLE

Does not rely on sunlight.

NADPH and ATP from the electron transport chain enter the Calvin cycle in the stroma to make food(glucose).

ATP provides energy to turn carbon dioxide and water into glucose.

NADPH provides electrons to keep the process going.

CALVIN CYCLE- 3 PHASES

1. Carbon fixation

2. Carbon reduction

3. RuBisCO regeneration

CO2 and H2O are used to

make glucose

CALVIN CYCLE OVERVIEW

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PHOTOSYNTHESIS OVERVIEW

PHOTOSYNTHESIS SUMMARY

Light-dependent phase Light-independent phase

Light energy is absorbed NADPH is converted to NADP+

and hydrogen ions

Oxygen gas is produced G3P is produced

Electrons move through the

electron transport chain

Glucose is produced

NADPH is generated RuBisCO is regenerated

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CELLULAR RESPIRATION

Both producers and

consumers get energy from

energy-containing molecules

in their food through cellular

respiration.

Cellular respiration happens

mostly in the mitochondria

and produces ATP.

THREE PHASES OF CELLULAR RESPIRATION

1. Glycolysis Cytoplasm

Produces pyruvate, NADH and 2ATP

2. Citric acid cycle Matrix of mitochondria

Produces NADH, CO2 and 2ATP

Provides third stage with electrons

3. Electron transport chain Inner membrane of

mitochondria

Uses electrons from NADH toproduce 32 ATP

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FERMENTATION

In the absence of oxygen,

some organisms can use

fermentation to obtain energy.

Like glycolysis, fermentation

takes place in the cytoplasm.

Because it includes no

electron transport chain,

fermentation produces far less

ATP than aerobic cellular

respiration.