Transcript Prentice Hall Biology

Photosynthesis
Photosynthesis
•
•
Energy and Life
Autotrophs and Heterotrophs
–
Autotrophs use light energy to produce food
Ex: all plants
– Heterotrophs obtain energy from food
they consume Ex: all animals
REMEMBER
• Cellular Respiration Makes ATP in the
mitochondria used for growth and life
processes
– Autotrophs (plants) and Heterotrophs (animals)
do this process
• ATP for Photosynthesis comes from light
energy
• Chemical Energy and ATP
– Storing Energy – ATP
– Releasing Energy - ATP
ADP
• Using Biochemical Energy
– ATP is used to power all cell activities including
photosynthesis
• ATP - basic energy source of all cells, both plants
and animals
– By breaking the bond between the second & third
phosphate, energy is released
– Adenosine Triphosphate - ATP - high energy
compound
– Adenosine Diphosphate - ADP - low energy
compound
ATP
ATP - Adenosine triphosphate - high energy compound
Adenine
Ribose
3 Phosphate groups
2 phosphate
groups
ADP - Adenosine Diphosphate - low energy compound
Comparison of ADP and ATP to a
Battery
ATP
ADP
Energy
Energy
Adenosine diphosphate (ADP) + Phosphate
Partially
charged
battery
Adenosine triphosphate (ATP)
Fully
charged
battery
Section Outline
• Investigating Photosynthesis
– Plants use the energy of sunlight to convert water and
carbon dioxide into oxygen and high energy sugars
• Van Helmont’s Experiment - Plant growth & weight
comes from water and CO2 in the air
• Priestley’s Experiment - plants produce O2
• Jan Ingenhousz - Light is necessary for plants to live
and produce O2 and sugar (this led to the
photosynthesis equation)
Photosynthesis Equations
6 CO2 + 6 H2O
Light
Carbon dioxide + water
Reactants
Carbon Dioxide
Water
C6H12O6 + 6 O2
Light
sugars + oxygen
Products
Sugar
Oxygen
Since oxygen is produced we can assume that
photosynthesis is occurring and what is
produced?
Glucose
Photosynthesis Location
• Takes place in the chloroplasts of the cell
Parts of a Chlorplast
Light Energy
Stroma (space) = Light
independent reaction
called Calvin Cycle
takes place here
Granum - stack
of thylakoids
Chloroplast
Thylakoid - photosystems are
CO2 + H2O clusters of pigments that absorb
light energy. Found in sac-like
photosynthetic membranes. Lightdependent reaction occurs here
Sugars + O2
• Light and Pigments
Chlorophyll-a and
chlorophyll-b are pigments
in a chloroplast
Green is
reflected = green
leaves on plants
Two reactions in photosynthesis
Process
Location
Reactants Products
Light
dependent
reactions
Thylakoid Sun
Water
ATP
NADPH
Oxygen
(Photosystem I&II)
Light
Stroma
independent
reactions
(Calvin Cycle)
ATP
NADPH
Carbon
Dioxide
Glucose
• Light-Dependent Reactions
– In light collecting pigments called Photosystem II & I
located In the thylakoid membrane ATP and NADPH
are sent to the stroma.
– Excited electrons are passed to electron transport
chain (similar to Cellular Respiration)
– What is given off?
• Oxygen, ATP, NADPH & 2 electrons
• NADPH and ATP are high energy and will be used
in the dark reaction cycle.
• Light-Dependent Reactions
– Inside a Chloroplast
– Photo II - Light hits chlorophyll in the thylakoid
membrane = H+ is a carrier
– Electron Carriers Photo I = re-energizes ATP &
NADPH
Photosynthesis: An Overview
Chloroplast
Light
H2O
Light absorbed
- photosystem II
ATP & NADPH
are formed photosystem I
NADP+
ADP + P
Calvin
Cycle
LightDependent
Reactions
ATP
NADPH
O2
Light-Dependent Reactions
Photosystem II
Hydrogen
Ion Movement
Chloroplast
ATP synthase
Inner
Thylakoid
Space
Thylakoid
Membrane
Stroma
Electron
Transport Chain
Photosystem I
ATP Formation
• The Calvin Cycle - occurs in the stroma
– High energy sugars are the product of Calvin
Cycle, uses CO2, and ATP & NADPH from Photo I
to make sugar. No light needed.
• RuBP- ribulose bisphosphate, 5C starts and
ends Calvin Cycle. Combines with CO2
• PGA – phosphoglyceric acid, 3C
• PGAL - phosphoglyceraldehyde
Photosynthesis: An Overview
Chloroplast
Light
H2O
CO2
NADP+
ADP + P
Calvin
Cycle
LightDependent
Reactions
ATP
NADPH
O2
Sugars
Calvin Cycle
CO2 Enters the Cycle
PGA
Energy Input
RuBP
ChloropIast
5-Carbon
Molecules
Regenerated
PGAL
6-Carbon Sugar
Produced
Sugars and other compounds
PHOTOSYNTHESIS VS. CELLULAR
RESPIRATION
The products of one are used as the reactants of the other: