Photosynthesis
An introduction
Class Brainstorm
Photosynthesis
The 5 Ws of Photosynthesis

Who?
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
What?
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
Chloroplasts
When?


Use light energy and CO2 to make sugars
Where?


Photoautotrophs
Need light
Why?

Source of energy for other organisms
Chlorophyll

Definition: A green colored pigment that
absorbs light

Two types: Chlorophyll a (blue-green) and
Chlorophyll b (yellow-green)

Consists of a porphyrin ring and a long
hydrocarbon tail

See page 139 for image

Porphyrin ring: a Mg atom at the centre
and a hydrocarbon ring of alternating
single and double bonds
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

Chlorophyll a has a methyl group (-CH3)
Chlorophyll b has an aldehyde group (-COH)
Hydrocarbon tail or Phytol tail: anchors
molecule to a membrane
Eukaryotic Autotrophs

Algae, Photosynthetic Protists, and Plants

Chlorophyll in organelles: chloroplasts

Chloroplasts found in leaves (gives them
green color)
Leaf Structure
Waxy cuticle
Upper
Epidermis
Palisade
Mesophyll
Spongy
Mesophyll
Mesophyll
Vascular
Bundle
Lower
Epidermis
Guard
Cells
Chloroplast: Photosynthetic “Factories”
Sketch and label a chloroplast
Inner and outer membrane
 Stroma – protein-rich semi-liquid
 Thylakoids – membrane bound sacs
contain chlorophyll and ETC
 Grana – stacks of thylakoids
 Lamellae – unstacked thylakoids that
connect grana


See page 144
Photosynthesis Overview

Step 1. Capture light
energy.

Step 2. Make ATP
and reduced NADP+

Step 3. Make
glucose and organic
compounds.
Light

Electromagnetic radiation (EM): light
is a form of energy


Visible light 380 (violet) -750 (red) nm
Travels in wave packets called photons

Absorption Spectrum: the wavelengths
of light that a pigment will absorb

Action Spectrum: the most effective
wavelength for photosynthesis

See page 152
Read “A Brief History of
Photosynthesis Research” on page 149150.
What experiment did J.B. Van Helmont
conduct? What did he conclude?
 What experiment did Joseph Priestly
conduct? What did he conclude?
 What is the source of O2 in
photosynthesis?

Hmwk
Prelab for Fermentation Lab
 Study for Quiz
 Hmwk (take-up on Tues)

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Qs: p145 #5b, 7, 9
Qs: p154 #1, 3, 6, 7, 8