4/8/11

Photosynthesis Chemical Reaction (Please Memorize!!!!)

• 6 CO2 + 6 H20 = C6H1206 + 6 O2
• (The numbers are actually subscripts and the "equals" sign is actually an arrow, meaning "yield")
• Reactants= 6 CO2 (Carbon Dioxide), 6 H20 (Water)
• Products= C6H1206 (Glucose), 6 02 (Oxygen Gas)
• Electrons added to Carbon dioxide to produce sugar Water molecules split and release oxygen gas (Sunlight provides the energy for this)
• Simple Summary of Photosynthesis
• 

Light Reactions and Calvin Cycle- 2 different cycles but work together

• Light Reactions
• convert solar energy to chemical energy
• make ATP (for energy storage) and NADPH (is an electron carrier)
• Reactants: NADP+ and ADP and Water (H20) and Light
• Products: Oxygen and ATP and NADPH
• Happens in thylakoid
• Calvin Cycle
• "light independent cycle" or "dark reactions"
• makes sugar from CO2
• uses ATP and NADPH from light reactions
• Reactants: CO2, ATP, NADPH
• Products: Sugar (there are other products too; any other organic product can result also)

Products of Light Reactions are needed for Calvin Cycle and products of Calvin Cycle needed for Light Reactions (Dependent on each other)

Light Reactions

(More Detailed)

• Light is energy!!!
• Sunlight- radiation or electromagnetic energy
• Visible Light is from 380-750 nm (wavelength)
• What we can see- ONLY light reflected from an object

EX- green leaves absorb red-orange and blue-violet light; reflecting green light (chloroplasts convert that absorbed energy into chemical energy)

• Chloroplast Pigments (found in photosystems)
• Chlorophyll a-
• absorbs blue-violet light and red light
• participates directly w/ light reactions
• Chloropyll b-
• absorbs blue and orange light
• increases range of light that can be absorbed (helps light reactions)
• Carotenoids-
• absorbs blue-green light
• absorbs and dissipates excessive light that could damage chlorophyll a

Photosystems and Light

• Photon- fixed quantity of light energy
• pigment molecules absorb photons of light, "exciting" the electrons so that they have more energy (higher energy state)
• electrons "falls" back to normal state (because the more energy they have the more unstable they are)
• releases energy (in form of light or heat)

arrows=light and heat energy being released as electron falls back to normal state

• Photosystems- have clusters of pigment molecules that act as antennae for photons of light
• Photons of light "jump" from pigment to pigment until they reach the Reaction Center (has chlorophyll a)
• Next to Reaction Center= Primary Electron Acceptor
• traps the excited light energy into ATP or NADPH
• 

2 types of Photosystems

• Water-splitting
• light energy to extract electrons from water
• releases oxygen as waste product
• NADPH Producing
• produces NADPH by transferring light excited electrons from chlorophyll to NADP+
• ALL ENERGY IS STORED IN CHEMICAL BONDS!!!!
• Electron transport chain
• connects the 2 photosystems, releases energy used to make ATP

• ATP Synthase- uses energy stored by H+ gradient to make ATP
• H+ molecules= more on the inside than on the outside, so they want to move to the outside

HW:

Read CH. 7

Pre-lab UP pg. 9-12

Next scribe= Kristen :):)