PhotosynthesisPart 1
description
Transcript of PhotosynthesisPart 1
Photosynthesis Part 1Pages 108 to 111
Autotrophs Name some common producers
› Plants, algae, some protists, cyanobacteria Define photoautotroph
› An organism that uses light energy to produce food
Define chemoautotroph› An organism that uses chemical energy to
produce food
Fig. 10-2
(a) Plants
(c) Unicellular protist10 µm
1.5 µm
40 µm(d) Cyanobacteria
(e) Purple sulfur bacteria
(b) Multicellular alga
Location of photosynthesis State the organelle of photosynthesis
› Chloroplast Where are chloroplasts concentrated in
plants?› The green tissue on the interior of the leaf› Mesolphyll
Fig. 10-3a
5 µm
Mesophyll cell
Stomata CO2 O2
Chloroplast
Mesophyll
VeinLeaf cross section
Gas Exchange Explain how gases are exchanged
between the plant and the environment.› Stoma are openings in the epidermis of
leaves› Guard cells surround the stoma and they
regulate the opening & closing of the stoma
› When open, CO2 can enter while O2 and H2O can exit
Fig. 10-3b
1 µm
ThylakoidSpace (lumen)
Chloroplast
GranumIntermembranespace
Innermembrane
Outermembrane
Stroma
Thylakoid
Structure of the
chloroplast
Thylakoid is site of
light reactions
Stroma is site of Calvin Cycle
Plants produce O2 by splitting H2O
1950’s – scientists used heavy isotope of oxygen (18O) to follow oxygen through photosynthesis.
Tagged oxygen of CO2 and found no tagged O2 given off
Tagged O2 of H2O and found tagged O2 given off
Reactants:
Fig. 10-4
6 CO2
Products:
12 H2O
6 O26 H2OC6H12O6
Photosynthesis is a Redox Reaction
Equation› 6CO2 + 6H2O Light C6H12O6 + 6O2
Redox reaction of photosynthesis› Oxidized:
H2O to O2
› Reduced: CO2 to C6H12O6
Overview of Photosynthesis Photosynthesis consists of the light
reactions (photo – absorbs light energy) and the Calvin cycle (synthesis – makes sugar)
2 stages of photosynthesis
Light ReactionsCalvin Cycle
Takes place in the thylakoids Split H2O Release O2 Reduce NADP+ to NADPH Produce ATP via photophosphorylation
Takes place in the stroma Forms sugar using
› CO2 from atmosphere› ATP and NADPH from light reactions
Starts with carbon fixation
Light
Fig. 10-5-4
H2O
Chloroplast
LightReactions
NADP+
PADP
i+
ATP
NADPH
O2
CalvinCycle
CO2
[CH2O](sugar)