qod - _______ is a membrane system found within the chloroplast, that are a flat, disc shaped...
TRANSCRIPT
QOD - _______ is a membrane
system found within the
chloroplast, that are a flat,
disc shaped structure.
QOD - _______ is a membrane
system found within the
chloroplast, that are a flat,
disc shaped structure.
PhotosynthesisPhotosynthesis
Chapter 9 Section 2 Chapter 9 Section 2
THE SUN: MAIN SOURCE OF ENERGY FOR LIFE ON
EARTH
Harvesting Light Energy
• Chloroplasts – organelle responsible for converting light energy into chemical energy (glucose)
Stru
ctur
e of
Chlo
ropl
ast
Parts:1. Outer membrane - permeable
2. Inner membrane – selectively
permeable3. Stroma – small area inside the
inner membrane4. Thylakoid – flat, discs that contain
pigments
5. Granum – Stack of thylakoids
6. Thylakoid membrane – structure
that is folded to create thylakoids
7. Pigments – substance the absorbs
the light energy and begins the
process of photosynthesis
Pigments
– Chlorophyll – reflects green and yellow (absorbs blues and reds) • Chlorophyll a –• Chlorophyll b –
– Carotenoids – reflect oranges, yellows and reds (absorbs blue and green)• Xanthrophyll – yellow• Carotene - orange
Why are plants green?
Reflected
light
Transmitted light
?
• When fall arrives, the leaves on trees turn red/orange/yellow, why is this? Which pigments are visible?
Now where
• Energy from the sun is absorbed by the pigments and then transferred to electrons at the reaction center.– Electrons becoming “excited”
• Gains energy and move to a higher energy level
Excitedstate
e
Heat
Light
Photon
Light(fluorescence)
Chlorophyllmolecule
Groundstate
2
(a) Absorption of a energy - sunlight
Excitation of chlorophyll in a chloroplast
e
Photosynthesis
• Consists of two phases– Light dependent phase (light is
required) – converts solar energy into chemical energy
– Light Independent (Calvin Cycle) (does not required light to occur) converts carbon dioxide and water to glucose
Light Dependent Phase
• 2 parts – First part creates ATP – Second part created NADPH (electron
carrying molecule)
Play
QOD – The sun’s energy is transferred to _______________ in the
reaction centers.
QOD – The sun’s energy is transferred to _______________ in the
reaction centers.
• Light Dependent Phase
– Occurs in the thylakoid membrane
Making ATP
Pigment
H2O ½ O2 + H2
2e-
2e-
Electron Transport Chain
ATP
Light
Indep
enden
t
Cycle
(Calv
in C
ycle)
To Part 2 making NADPH
ATP Synthase
H+
H+
Hydrolysis
• Breaking down of water into hydrogen and oxygen
Pigment
2 e-
2e-
NADP+
NADPH
e
2e-
+
Light Independent Cycle(Calvin Cycle)
Electron Transport Chain
Making NADPH
H+
H+
From Part I
From Part I
NADPH
• High energy electron carrying that takes that energy to the Light Independent cycle to make glucose
Making Sugar• The high energy carrying
molecules, ATP and NADPH combine with the carbon from carbon dioxide to make Glucose.
• Light Independent Cycle (Calvin Cycle) – occurs in stroma
Play
RuBP (5 carbon)
CO2
2 Pgal (3 carbon)
Rubisco – enzyme that attaches the carbon
6 carbon structure created is not stable and immediately breaks down into 2, 3 carbon structures
2, 3 carbon Goes through a series of step to be modified – uses ATP and NADPH
2 ATP
2 ADP
2 NADPH
2 NADP+
PGAL goes through a series of reaction to become a 5 carbon structure
1 Pgal drops down ever three rotations. This will later become glucose after six rotations
ATP
ADP
Step 1: Carbon Fixation
Step
2: T
rans
ferrin
g En
ergy
Step 3: Making Sugar
RuBP (5 carbon)
Step 4: Recycling
Calvin Cycle
ATP & NADPH enter from the light dependent cycle.
Cycle starts over
• Light Independent (Calvin Cycle)
– Occurs in the stroma of the chloroplast
• The Calvin cycle makes sugar from carbon dioxide– ATP generated by the light
reactions provides the energy for sugar synthesis
– The NADPH produced by the light reactions provides the electrons for the reduction of carbon dioxide to glucose
LightChloroplast
Lightreactions
Calvincycle
NADP
ADP+ P
• The light reactions convert solar energy to chemical energy– Produce ATP &
NADPH
AN OVERVIEW OF PHOTOSYNTHESIS
Factors
• There are 3 environmental factors that affect photosynthesis– Levels of carbon dioxide– Temperature– Light intensity
• Questions?
• QUIZ WEDNESDAY!!!!!!!!