PHOTOSYNTHESIS Sun Hwa Dong. Photosynthesis Produces organic substances Uses light Energy, Simple inorganic substances Light Energy to Chemical Energy.

PHOTOSYNTHESIS

Sun Hwa Dong

Photosynthesis

Produces organic substances

Uses light Energy, Simple inorganic substances

Light Energy to Chemical Energy

Absorption of Light

Sunlight = White light, but made up of wavelengths like red, green, blue

Pigments absorb lights Red, Blue > Green Green light cannot be reflected

Absorption of Energy

Some used to produce ATP. Some split water molecules – Photolysis

of Water This forms Oxygen and Hydrogen.

CO₂ is absorbed to make organic substances. Carbon in a gas to carbon in solid compounds –

Carbon Fixation This involves use of Hydrogen from photolysis

and Energy from ATP.

Measuring Rates of Photosynthesis

Production of O₂ : Aquatic plants release bubbles of O₂

Uptake of CO₂ :If CO₂ is absorbed from water, the pH of water rises

Increases in biomass : the rate of increase in biomass means more photosynthesis.

Effect of Light Intensity

Effect of CO₂ Concentration

Low light intensity - shortage of ATP and hydrogen

Effect of Temperature

CO₂ fixation is catalyzed by enzymes.

Limiting Factors

Each factors can limit the rate when below optimal level.

Combination of factors – only one factor furthest from its optimum limits

When 2 of the factors are equally close to optimum, increasing them rises the rate.

Action and Absorption Spectra

Action Spectra: % use of wavelengths of light in photosynthesis

Absorption Spectra: % use of the wavelengths of visible light that are absorbed

Photoactivation

Chlorophyll & accessory pigments -Photosystem

Chlorophyll molecules in photosystem absorb light energy and pass it to 2 special chlorophyll molecules in the reaction centre.

Electron within the molecules become excited and photoactivated.

Photophosphorylation

Photophosphorylation: the production of ATP, using E from light which is carried out by thylakoids

Thylakoids: regular “stack” of membranes that contain Photosystem I & , ATP Ⅱsynthase, a chain of electron carriers

Chemiosmosis

1. Protons pass across membrane and release E which is used by ATP synthase to produce ATP.

2. The coupling of ATP synthesis to electron transport via a concentration gradient of protons → CHEMIOSMOSIS

Chloroplasts structure

Chloroplast envelop Thylakoids Small fluid filled spaces inside Thylakoids Mostly have stacks of thylakoids called grana Colorless fluid around Thylakoids = stroma

Bibliography Course Companion p95-108 Study Guide p21, p75,p76-81 Pearson: p 74-78, p227-236 http://biotransitioneng.wordpress.com/2009/05/10/fossils-fuels-%E2%80%93-a-great-problem/ http://botit.botany.wisc.edu/images/130/Chlorophyta/Eremosphaera_Images/Chloroplasts_MC.html Pearson Education, Inc., publishing as Benjamin Cummings http://www.cbu.edu/~seisen/Photosynthesis.htm http://helpmyphysics.co.uk/wordpress/?m=200902 http://botit.botany.wisc.edu/images/130/Chlorophyta/Eremosphaera_Images/Chloroplasts_MC.html http://generalhorticulture.tamu.edu/lectsupl/physiol/physiol.html http://fhs-bio-wiki.pbworks.com/Factors-effecting-the-rate-of-photosynthesis http://reefbuilders.com/2010/08/23/chlorophyll-f-a-newly-discovered-photosynthetic-pigment-uses-infrared-light/ www.theoremeinnovation.com/revolution-en.html www.firstrays.com/plants_and_light.htm http://image.absoluteastronomy.com/images/encyclopediaimages/c/ch/chemiosmosis1.png www.cbs.dtu.dk/staff/dave/roanoke/bio101ch07.htm micro.magnet.fsu.edu/.../chloroplasts.html

Vocabulary

Photosynthesis: The process used by plants and other organisms to produce all their own organic substances (food), using only light energy and simple inorganic substances.

Photolysis of water: Splitting of water by energy absorbed by chlorophyll. Carbon Fixation: The conversion of carbon in a gas to carbon in solid compounds. Photosystem: protein complexes involved in photosynthesis Photoactivation: The initial stage of photosynthesis in chlorophyll Molecules where

the presence of light Energy raises the energy. Chemiosmosis: The coupling of ATP synthesis to electron transport via a

concentration gradient of protons Photophosphorylation: the production of ATP, using E from light which is carried out

by thylakoids Thylakoids: regular “stack” of membranes with very small fluid-filled spaces inside

that contain Photosystem I & , ATP synthase, a chain of electron carriersⅡ Grana: stacks of thylakoids Stroma: a colorless fluid around the thylakoids that contains many different enzymes