Download NOTES Photosynthesis 2013

Photosynthesis
Photosynthesis
Process uses the sun’s energy to make glucose
Carried out in green plants and some bacteria
Purpose is to trap sun’s energy and store it in
glucose (food for the plant)
Photosynthesis occurs in the chloroplast
photons
SUN
6CO2 + 12H2O C6H12O6 + 6O2 + 6H2O
carbon dioxide + water  glucose + oxygen + water
2
6CO2 + 12H2O C6H12O6 + 6O2 + 6H2O
carbon dioxide + water 
glucose + oxygen + water
3
Stomata (stoma)
Pores in a plant’s cuticle through which
water and gases are exchanged
between the plant and the
atmosphere.
Oxygen
(O2) & Water
Carbon Dioxide
(CO2) & Water
Guard Cell
Guard Cell
Found on the underside of leaves
Chloroplast
Organelle where photosynthesis
takes place.
Stroma: gel filled space
Outer Membrane
Thylakoid: green disks
Granum: stack
Inner Membrane
of thylakoids
Inter
Membrane
Space
Thylakoid stacks are connected together
6
Thylakoid
Thylakoid Membrane
Granum
Thylakoid Space
(Lumen)
Grana make up the inner membrane
7
Why are
plants
green?
Electromagnetic Spectrum
Pigments
Pigments are light-absorbing
compounds.
Pigments appear colored because they
absorb light of certain wavelengths
and reflect that of others.
Chlorophyll a and b are the primary
pigments in green plants that absorbs
red and blue/violet light and reflects
green light.
Structure
of
Chlorophyll
Accessory Pigments
Chloroplasts also contain other pigments
called accessory pigments that capture
other wavelengths to absorb more energy.
Carotenoids-yellow/orange
Anthocyanin-red/purple
Photosynthesis Reactions
CO2
Dark Reactions
ATP
NADPH
H2O
+
CO2
Sugars
Light Reactions
O2
14
Light and Dark
Reactions
Photosynthesis Steps
1. Light reaction (Light-dependent reaction)
Chlorophyll traps sunlight and makes
electrons and ATP to run the dark
reaction.
2. Dark reaction (Light-independent reaction)
Calvin Cycle uses ATP and electrons from
the light reaction and carbon dioxide from
the air to make glucose.
ATP
All organisms require energy for:
Active transport
Cell division
Movement
Production of proteins
17
NADPH
NADP+ is an electron acceptor
NADP+ + 2e- + 2 H+  NADPH + H+
LIGHT REACTION
Requires light
Pigments absorb
photons of light and
excite electrons
Occurs in two
photosystems in the
thylakoid membranes
Photosystem: a unit
of several hundred
chlorophyll molecules
and associated
acceptor molecules
Light Reaction Summary
Input:
light energy
H2O
Output:
ATP
NADPH
O2
20
Dark Reaction (Calvin
Cycle)
American scientist Melvin
Calvin
Occurs in the stroma.
Uses ATP and NADPH from
light reactions.
Uses CO2 to produce
glucose (C6H12O6).
To produce 1 glucose: it
takes 6 turns of the cycle and
uses 18 ATP and 12 NADPH.
Dark Reactions Summary
Input:
ATP
NADPH
CO2
Output:
ADP
NADP+
H2O
Sugars (glucose)
22
Rate of Photosynthesis
The rate at which a plant can carry photosynthesis is affected
by its environment.
1. Temperature – enzymes
directly impacted
2. Light intensity – no light
= no photosynthesis
3. Water - required
4. [CO2]- Calvin (Dark) cycle
requirements
The End!