Lesson 2 chloroplast structure and leaf adaptations
Transcript of Lesson 2 chloroplast structure and leaf adaptations
Photosynthesis #1
Learning objectives...•Link leaf structure to efficiency in photosynthesis
•Review chloroplast structure•Describe and explain the role of photosynthetic
pigments in light harvesting
Photosynthesis overview and chloroplast structure
• (d) state that in plants photosynthesis is a two-stage process taking place in chloroplasts;
• (e) explain, with the aid of diagrams and electron micrographs, how the structure of chloroplasts enables them to carry out their functions;
Stages of photosynthesis...
• Light harvesting
• Light independent
• Light dependent
(d) state that in plants photosynthesis is a two-stage process taking place in chloroplasts
Leaf adaptations…
Why might a plant be variegated?
Cross-section of a leaf
100 m
Mesophyll cells
How are chloroplasts positioned?
• http://www.saps.org.uk/secondary/teaching-resources/795-video-clip-chloroplasts-and-starch
Chloroplast structure…
a
hg f
e
dcb
Schematic chloroplast
sealed thylakoid membrane
membrane-enclosed stroma
Thylakoid membrane
• chlorophyll• light-harvesting• electron transfer
• O2 evolution
• energy production
Stroma
• Rubisco
• CO2 fixation
• sugar and starch synthesis
Peachloroplast
1 m
a) Membrane-bound sacs containing chlorophyll moleculesb) Liquid that contains a variety of photosynthetic enzymes and
starch grains.c) Stacks of membrane bounded, flattened, discoid sacs,
arranged like neat piles of coins.
A. ThylakoidsB. StromaC. Grana (1 granum)
Summary test...• Leaves are the main site of photosynthesis which occurs
mainly in the (1) cells. They have numerous (2) that allow exchange of gases between themselves and the air around them and a network of veins that make up the tissue (3) that brings water to the leaf and (4) that carries away (5) produced in photosynthesis. Chloroplasts are surrounded by a double membrane or (6) and possess both (7) and (8) that enable them to make their own proteins. Inside, there is a fluid-filled matrix called the (9) that carries out the (10) reaction and also contains structures like (11) grains and oil droplets. Within this matrix are disc-like structures called (12) stacked in groups called (13) where the (14) reaction of photosynthesis takes place.
Light is absorbed by individual chlorophylls in the light-harvesting complexes
Energy is transferred from one pigment to another via Resonance Energy Transfer
This transfer funnels the energy to a reaction centre
where electron transfer starts
Energy transfer in light-harvesting complexes