8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 1/33

PHOTOSYNTHESIS

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 2/33

Different Types of Organisms as to

Mode of Nutrition:

1. Photoautotrophs

- organisms obtain their energy through

photosynthesis

ex. Plants, algae, photosynthetic bacteria2. Heterotrophs

- rely on other organisms for organic molecules to

build their bodies

3. Chemoautotrophs- obtain their carbon from CO2 and energy from

inorganic chemicals

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 3/33

Differences between autotrophs and

heterotrophs

Source of energy

Source of building

materials

Organisms

Photoautotrophs Heterotrophs

Sunlight

carbon dioxide

photosynthetic plants

AlgaeCyanobacteria

Photosynthetic bacteria

 

Food:proteins

carbohydrates

Food

Completeley parasitic plants 

FungiAnimals; protozoa

Non-photosynthetic parts of 

plants

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 4/33

Photosynthesis

Is the process by which green plants and

autotrophic organisms synthesize food.

6CO2 + 12H20 C6H12O6 + 6O2 + 6H2Ochl 

light

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 5/33

AN OVERVIEW OF PHOTOSYNTHESIS 

• Photosynthesis is the process by which

autotrophic organisms use light energy to

form sugar and oxygen gas from carbon

dioxide and water

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 6/33

Photosynthesis

- use light energy to

convert CO2 and H2O into

sugar

- chloroplast

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 7/33

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 8/33

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 9/33

The location and structure of chloroplasts

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 10/33

Chloroplast

- plastid

- organelle involved in

making or storing food and

pigments

- chlorophyll

- site of photosynthesis

- stem and leaves

-3-5um in diameter,spherical or elongated

- 2 membranes

- thylakoids

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 11/33

Grana

- Conversion of solarenergy to chemical

energy takes place

within the

membrane of the

thylakoids

Stroma

- site of sugarproduction and storage

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 12/33

2 Series of Reactions

I. Light Reaction

II. Dark Reaction/ Calvin Cycle

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 13/33

An overview of photosynthesis

H20

Light Chloroplast 

CO2 

CALVIN

CYCLE

(in stroma) 

LIGHT

REACTIONS

(in grana) 

ATP 

NADPH 

NADP+ 

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 14/33

I. Light Reactions

• Thylakoid membrane

• Photo part of 

photosynthesis

•Capture light energy

• O2 (by product)

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 15/33

II. Calvin Cycle

• Stroma

• Synthesis part of photo-

synthesis

• Assembles 3 simple

carbon sugars using ATP

and NADPH from light

reactions and CO2 fromthe air

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 16/33

LIGHT REACTIONS

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 17/33

 

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 18/33

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 19/33

 

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 20/33

The Nature of Light

• Wavelength is the

distance from peak to

peak

• Energy is inverselyproportional to the

wavelength

• Longer wavelength the

less energy

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 21/33

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 22/33

Types of Chlorophyll

1. Chlorophyll a

- only pigment directlyinvolved in lightreactions

- absorbs light from blueviolet and red ranges of spectrum

- wavelength in red and

blue ranges of spectrumstrongly drivephotosynthesis

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 23/33

Accessory pigments

1. Chlorophyll b c, d, e

- does not take part directly in light reactions

- transmit absorbed energy to chlorophyll a

molecules- accessory pigment

2. carotenoids

- absorb blue-green light and absorb yellow oryellow- orange lights

3. xanthophyll

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 24/33

Light energy enters photosynthesis at locations

called photosystems ( light harvesting units)

Primary

electron acceptor 

PHOTOSYSTEM 

Reaction center 

Pigment

molecules

of antenna

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 25/33

 

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 26/33

 Movement of electrons in the light reactions

- little chlorophyll b

- Almost same amount

of chlorophyll a and b

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 27/33

II. CALVIN CYCLE

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 28/33

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 29/33

Internal Anatomy of Leaf- Dicot

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 30/33

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 31/33

CAM Photosynthesis

•

Crassulacean Acid Metabolism• Carbon dioxide is converted to an acid and stored during

the night

• Stomata open at night

•

During the day the acid is broken and carbon dioxide isreleased to Rubisco for photosynthesis

Adaptive Value:

- better water use efficiency (lower transpiration rates)

- thrive in conditions of high daytime temperatures• CAM plants include many succulents such as

cactuses, agaves, some orchids and bromeliads

pineapple

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 32/33

8/6/2019 Revised Photosynthesis2nd Sem 2010-11 2 - Copy

http://slidepdf.com/reader/full/revised-photosynthesis2nd-sem-2010-11-2-copy 33/33

CAM plants store CO2 in a C4 acid at night for use

in the Calvin Cycle during the day.