Photosynthesis Notes

Photosynthesis Notes - Photosynthesis 3.1 Photosynthetic...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Photosynthesis 3.1- Photosynthetic Organisms: Chlorophyll : light-absorbing green coloured pigments that begin the process of photosynthesis Two main forms of chlorophyll: Chlorophyll a (blue-green) and Chlorophyll b (yellow-green) Porphyrin is the light-absorbing portion of the chlorophyll molecule, contains a Mg atom surrounded by a hydrocarbon ring Chlorophyll a and b differ with one functional group This difference affects the type of light energy each chlorophyll molecule can absorb All photosynthetic organisms use chlorophyll a as the primary light absorbing pigment Cyanobacteria are the largest group of photosynthesizing prokaryotes Cyanobacteria are like blue-green algae and they are unicellular Chloroplasts: the photosynthetic membranes that contain chlorophyll and chlorophyll is what gives leaves, stems and unripened fruit their distinct colour Leaves are the primary photosynthetic organs of most plants Primary function of leaves is to undergo photosynthesis PLANT STRUCTURE: Leaves: primary function →photosynthesis. Thin, narrow to maximize SA for sunlight and CO2. Epidermis: allows light to pass through to mesophyll Mesophyll (Palisade): contain chloroplasts where most of the photosynthetic cells are located Chloroplasts: vacuoles with flat pancakes of thylakoids Guard cells: create microscopic openings called stomata, contract and expand to let in CO2 or let out water. Stomata: openings that allow for exchanges of gases between air spaces in the interior of the leaf and the atmosphere Transpiration: loss of water vapour from plant tissues, primarily through the stomata Transpiration Pull: move water and minerals up roots Evaporative Cooling effect: Prevents from drying up. Transpiration
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
On a hot sunny day, a tree may lose more than 200 L of water through stomata by transpiration Transpiration assists photosynthesis in 2 ways: First, it creates a “transpiration pull” that helps move water, minerals and other substances from the roots of plants where they are absorbed by the leaves where they are used. Second, it produces an evaporative effect that prevents leaves from heating to temperatures that can inhibit or even denature the enzymes used in the Calvin’s Cycle. Guard cells control the size of the stomata by changing their shape in response to changes in environmental conditions STOMATA: Size of guard cells changes when water moves in/out→ due to diffusion of K+ Open: Guard cells swollen (turgid) In morning, light activates receptors in guard cell membranes Activates proton pumps that pump H+ ions out and K+ into cell. Water fallows. They swell and stomata open. Reduction in
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/05/2011 for the course PHYS 1010 taught by Professor Tomkirchner during the Spring '11 term at York University.

Page1 / 11

Photosynthesis Notes - Photosynthesis 3.1 Photosynthetic...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online