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17.0 PHOTOSYNTHESIS
17.0 Photosynthesis
1) 17.1 Overview of photosynthesis 2) 17.2 Absorption spectrum of
photosynthesis pigments 3) 17.3 Light Dependent Reaction 4) 17.4 Light Independent Reaction/Calvin
Cycle 5) 17.5 Alternative mechanisms of carbon
Fixation : Hatch Slack (C4) and Crassulacean Acid Metabolism (CAM) pathways
17.0 Photosynthesis
1) 17.1 Overview of photosynthesis 2) 17.2 Absorption spectrum of
photosynthesis pigments 3) 17.3 Light Dependent Reaction 4) 17.4 Light Independent Reaction/Calvin
Cycle 5) 17.5 Alternative mechanisms of carbon
Fixation : Hatch Slack (C4) and Crassulacean Acid Metabolism (CAM) pathways
Learning outcomes :
17.1 Overview of Photosynthesis
Give overall outline of photosynthetic
process that lead to the production of
glucose
PHOTOSYNTHESIS
• Photosynthesis is the synthesis of organic
compounds from simple inorganic materials,
namely carbon dioxide and water
• With the presence of chlorophyll that absorbs
the light energy
• Whereby the light energy is converted to
chemical energy that is stored in glucose or
other organic compound such as proteins and
lipids
Learning Outcomes : 17.1 : Give overall outline of photosynthetic process that leads to the production of glucose
• It occurs in plants, algae and certain prokaryotes
• The overall equation for photosynthesis is :
6CO2 + 12H2O + 18ATP + 12NADPH --->
C6H12O6 + 6O2 + 6H2O + 18ADP + 12NADP+ +
18Pi
• Oxygen is released as a by-product
• Photosynthesis is an endergonic process
Learning Outcomes : 17.1 : Give overall outline of photosynthetic process that leads to the production of glucose
CHLOROPLAST
• Any green part of a plant has chloroplasts.
• However, the leaves are the major site of photosynthesis
for most plants.
• There are about half a million chloroplasts per square
millimeter of leaf surface.
• The color of a leaf comes from chlorophyll, the green
pigment in the chloroplasts.
• Chlorophyll plays an important role in the absorption of
light energy during photosynthesis.
Learning Outcomes : 17.1 : Give overall outline of photosynthetic process that leads to the production of glucose
Structure of Chloroplast
Learning Outcomes : 17.1 : Give overall outline of photosynthetic process that leads to the production of glucose
• Chloroplasts are found mainly in mesophyll cells
forming the tissues in the interior of the leaf.
• O2 exits and CO2 enters the leaf through microscopic
pores, stomata, in the leaf.
• Veins deliver water from the roots and carry off sugar
from mesophyll cells to other plant areas.
Learning Outcomes : 17.1 : Give overall outline of photosynthetic process that leads to the production of glucose
• Each chloroplast has two membranes around a central
aqueous space, the stroma.
• In the stroma are membranous sacs, the thylakoids.
• These have an internal aqueous space, the thylakoid
lumen or thylakoid space.
• Thylakoids may be stacked into columns called grana
Learning Outcomes : 17.1 : Give overall outline of photosynthetic process that leads to the production of glucose
17.0 Photosynthesis
1) 17.1 Overview of photosynthesis 2) 17.2 Absorption spectrum of
photosynthesis pigments 3) 17.3 Light Dependent Reaction 4) 17.4 Light Independent Reaction/Calvin
Cycle 5) 17.5 Alternative mechanisms of carbon
Fixation : Hatch Slack (C4) and Crassulacean Acid Metabolism (CAM) pathways
Learning outcomes :
17.2 Absorption spectrum of
photosynthetic pigments
State the photosynthetic pigments
involved in photosynthesis
PHOTOSYNTHETIC PIGMENTS
• Photosynthesis occurs in the chloroplasts in which
chlorophylls are the most important pigments.
• It gives the green colour to the plants
• Chlorophyll is the green pigment that absorbs light
energy and it is a mixture of pigments that comprises :
Chlorophyll a (blue-green pigment) & chlorophyll b
(yellow-green pigment)
Some carotenoids : B-carotene (orange) & xanthophyll
(yellow)
Phaeophytin (grey)
Learning Outcomes : 17.2 : State the photosynthetic pigments involved in photosynthesis
• Chlorophylls a : mainly absorbs light in blue-violet
(430nm) and red (662 nm) region
• Chlorophylls b : absorbs light 453 nm and 642 nm
• Carotenoids : carotenes, xanthophylls, absorbs blue-
violet region (460-550 nm)
Light absorption spectrum
Learning Outcomes : 17.2 : State the photosynthetic pigments involved in photosynthesis