PHOTOSYNTHESIS
PHOTOSYNTHESIS
PHOTOSYNTHESIS - Process that converts light energy into the chemical energy that
is stored in sugars.
Light + 6CO2 + 6H2O → C6H12O6 + 6O2
Pigments - Molecules specialized for absorbing certain wavelengths of light.
Ex. chlorophyll, carotene, xanthophylls
- Leaves have different pigments to absorb the many different wavelengths
of light.
- Pigments other than chlorophyll are always present, but only seen when the
unstable chlorophyll is broken down and not regenerated during the autumn.
- Chlorophyll absorbs red and blue wavelengths of light, reflects green light.
LIGHT-DEPENDENT REACTIONS –
- Occur in the thylakoids of the chloroplast. Process converts light
energy into chemical energy.
- Chlorophyll and other pigments are located in units called photosystems,
which are inside the thylakoid membrane. Photosystems absorb light
and energize electrons (e-).
- Absorbs sunlight and uses this energy to help split water (photolysis), energize electrons, and produce the molecules ATP and NADPH.
(these are energy-storing molecules)
- Oxygen is released as a product when water is split. H+ ions and
e- are also released from water.
- High-energy electrons are accepted by NADP+ to form NADPH
- ATP synthase (an enzyme) converts ADP into ATP. This reaction
is powered by the movement of H+ ions down the concentration
gradient.
(underlined words are products of the light-dependent reactions)
PHOTOSYSTEM II –
- Water is split to form H+ ions, oxygen, and electrons (e-)
- Light absorbed by chlorophyll energizes electrons which will be passed
along the electron transport chain (ETC).
ELECTRON TRANSPORT CHAIN (ETC) –
- High energy e- are transferred to a series of electron carriers.
Energy from the e- is used to pump H+ ions across the thylakoid
membrane against the concentration gradient (into the thylakoid).
PHOTOSYSTEM I –
- Light absorbed here re-energizes the electrons. The e- (and H+ ions )
are accepted by NADP+ to form the energy-storing molecule called
NADPH.
ATP FORMATION –
- H+ ions inside the thylakoid flow down the concentration gradient
through a membrane protein called ATP synthase. The energy
released by falling H+ ions is used to power the change of ADP
into ATP.
LIGHT-INDEPENDENT REACTIONS –
- Occurs in the stroma of the chloroplast
- Includes the Calvin cycle which uses the energy stored in ATP and
NADPH to produce glucose from CO2
- Carbon Fixation incorporates inorganic CO2 from the air into a usable
organic compound.
- RuBisCo is an enzyme that catalyzes the reaction between CO2 and
organic RuBP (5-carbon sugar) in the carbon fixation reaction.
- 6 CO2 are required to produce 1 glucose molecule
- The first stable substance formed during the Calvin cycle is a 3-carbon
compound called PGA.
- High-energy phosphates from ATP and electrons from NADPH are
combined with PGA to form another 3-carbon compound called PGAL
(also known as G3P or GAP)
- For every 3 CO2 molecules that enter the Calvin cycle, 1 PGAL leaves
- A complex series of reactions, requiring ATP, rearrange other PGAL
molecules into RuBP molecules to keep the cycle going.
(Ex. 5 PGAL → 3 RuBP) (1 ATP needed for each RuBP produced)
- 2 PGALs can be combined to form glucose
................
................
In order to avoid copyright disputes, this page is only a partial summary.
To fulfill the demand for quickly locating and searching documents.
It is intelligent file search solution for home and business.
Related searches
- products of photosynthesis kids
- biology photosynthesis notes
- biology photosynthesis quiz
- biology photosynthesis quizlet
- honors biology photosynthesis quiz
- biology photosynthesis test
- photosynthesis process step by step easy
- biology photosynthesis worksheet
- ap biology photosynthesis worksheet
- biology corner photosynthesis worksheet
- biology photosynthesis worksheet answers
- photosynthesis coloring worksheet pdf