Photosynthesis

An introduction

Photosynthesis

Class Brainstorm

The 5 Ws of Photosynthesis Who?

Photoautotrophs What?

Use light energy and CO2 to make sugars Where?

Chloroplasts When?

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 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 cuticleUpper EpidermisPalisade

Mesophyll

Lower Epidermis

MesophyllSpongy Mesophyll

Vascular Bundle

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 149-150. 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)

Qs: p145 #5b, 7, 9 Qs: p154 #1, 3, 6, 7, 8