Download Photosynthesis - mleonessciencepage

Photosynthesis
All organisms use energy to carry out
the functions of life.
Agenda
What are the reactants and products of photosynthesis?
What are the colors of the visible light spectrum?
In what cellular organelle does photosynthesis take place?
Why is photosynthesis important?
How is the process of photosynthesis in C4, C3, and CAM plants
different?




Go over Vocabulary Definitions
Photosynthesis Web Activity
Notes: Photosynthesis-light & pigments
Worksheet: Absorption of Chlorophyll
Importance of Photosynthesis


Transforms sunlight energy into chemical energy
stored in molecules (bonds)
Bond energy within triose phosphate formed in
photosynthesis is transferred between organisms
within the food pyramid (more energy at bottom
than top)


Triose phosphate (glyceraldehyde 3-phosphate) is
converted to carbohydrates, lipids, amino acids
Photosynthesis releases oxygen to atmosphere
Reactants



Sunlight
Water
Carbon dioxide
Products
Triose phosphate
(Glucose)
Oxygen
H2O + CO2 + light energy  (C6H12O6)+ O2
Capturing the Light
“Light dependent reactions” take place in
chloroplast
found in mesophyll
of leaf.

Grana within
thylakoid membrane
 Stroma-solution
Surrounding grana

Light and Pigments



Sun light appears white, but it is actually
composed of a variety of colors called the
Visible Spectrum.
Light can be reflected, absorbed or
transmitted by an object.
Pigment absorb light, therefore the light
reflected or transmitted no longer appears
white
Peaks indicate
Light absorbed
Trough where light is
reflected


The color you
see is what is
reflected.
Ex. Chlorophyll
(a,b) absorbs
blue and red
light, but
reflects green
light
Review
What are the reactants and products of
photosynthesis?
What are the colors of the visible light spectrum?
In what cellular organelle does photosynthesis take
place?
Why is photosynthesis important?

Complete the Absorption of Chlorophyll
Worksheet
Agenda
How does the structure of a chloroplast lead to light
absorption?
What are the variety of pigments found in the
thylakoid of a chloroplast?




Review Light Absorption
Review Vocabulary
Notes: Structure of Leaf & pigment
Complete Pigments & Light Absorption PSSA Worksheet
Structure of Leaf


Leaves are a plant's main photosynthetic
organs.
Gases and water vapor come in and out of
a leaf through its stoma.

Epidermis



Outer layer which produces a waxy waterproof
coating.
undersurface produces guard cells, which swell and
shrink to close and open the pores (stomata) which
control the loss of water vapor (transpiration) and
the entry of carbon dioxide.
Mesophyll

contain the photosynthetic cells of the leaf.
long columnar cells nearer the surface (palisade
parenchyma)
 looser irregular cells beneath (the spongy mesophyll
parenchyma).

Log onto:
http://www.phschool.com/science/biolog
y_place/biocoach/photosynth/intro.html
Select:
#4 Structure of a Leaf
#6 Chloroplast Structure
Chloroplast
Pigments

Within the thylakoid
are a variety of
pigments.




Chlorophyll ayellow/green
Chlorophyll bblue/green
Carotenoids - orange
Each pigment absorbs
a different wavelength
of light.


Chlorophyll a is directly involved in the
light reactions of photosynthesis
Chlorophyll b and carotenoids are
considered to be accessory pigments,
assisting Chlorophyll a in capturing light
energy.
Review
How does the structure of a chloroplast lead to light
absorption?
What are the variety of pigments found in the
thylakoid of a chloroplast?

Complete Pigments & Light Absorption
PSSA Worksheet
Agenda
What occurs during photolysis?
How does the structure of a photosystem lead to it function?
What is the main purpose of the light dependent phase of
photosynthesis?



Vocabulary Quiz
Notes: Photolysis & light Reaction
Complete Section 6-1 Review Worksheet
& Photosynthesis PSSA Worksheet
Photolysis

Splitting of water molecules



Oxygen is released through stomata
H+ picked up by NADP and pumped through
thylakoid to stroma for Calvin cycle
Carbon Dioxide is absorbed through
stomata and used in the Calvin cycle
Light Dependent Phase-thylakoid

Groups of chlorophyll and carotenoid
pigment molecules are found in the
thylakoid membrane




Photosystem I
Photosystem II
Accessory pigment molecules in both
photosystems absorb light energy causing
electrons to become excited.
Energy is passed within the photosystem
through pigment molecules to chlorophyll a
Electron Transport Chain



Aided by enzymes, therefore affected by temperature
Excited electrons leave chlorophyll a molecules to a
primary electron acceptor in the stroma of the
chloroplast
Electron acceptor donates electrons to a series of
molecules located in the thylakoid
allowing protons(H+) to move into the thylakoid
Electron Transport Chain cont.

Photosystem I electrons are replaced by
electrons from Photosystem II


Photosystem II gets the electrons from
splitting water, for every 2 water split, 4
electrons are available
If this did not happen, photosynthesis would
stop
Chemiosmosis/ATP Synthase



Relies on a concentration gradient of
protons across the thylakoid membrane.
Protons are pushed through ATP Synthase
in the thylaloid membrane
Adds a phosphate group to ADP making
ATP
Review
What occurs during photolysis?
How does the structure of a photosystem lead to
it function?
What is the main purpose of the light dependent
phase of photosynthesis?


Complete Section 6-1 Review Worksheet
Complete Photosynthesis & Light
Absorption PSSA Worksheet
Agenda
What is the main purpose of the light independent phase of
photosynthesis?
How is the process of photosynthesis in C4, C3, and CAM plants
different?




Review
Lab: Plant Stoma
Notes: Light Independent Phase &
Alternative Pathways
Complete Biochemistry of Photosynthesis
PSSA Worksheet
Light Independent Phase

Also called the Calvin Cycle
Produces organic compounds, using the energy stored in ATP
and NADPH in the light reactions and carbon dioxide

Steps


CO2 diffuses into stroma combining with an enzyme
(RuBP), the molecule is split and becomes 3-PGA

Each PGA is converted to another molecule(3phosphate) in a 2 part step
One receives a P from ATP, and the other receives a
Proton (H+) from NADPH
 One G3P leaves to make carbohydrates
 One is converted back to RuBP to be used again

Summary
Carried out by Plants

C3 plants.





C4 plants.






because the CO2 is first incorporated into a 3-carbon compound.
Stomata are open during the day.
Photosynthesis takes place throughout the leaf.
Most plants are C3.
because the CO2 is first incorporated into a 4-carbon compound.
Stomata are partially open during hottest part of the day.
into the plant very quickly, and then it "delivers" the CO2 directly to
RUBISCO for photosynthesis.
Photosynthesis takes place in inner cells
Ex. Corn, Sugar Cane, Crab grass
CAM plants. CAM stands for Crassulacean Acid Metabolism


because the CO2 is stored in the form of an acid before use in
photosynthesis.
Stomata open at night (when evaporation rates are usually lower) and are
usually closed during the day. CAM plants include many succulents such
as cactus, agaves, bromeliads and also some orchids
Review

What is the main purpose of the calvin
cycle of photosynthesis?
•Complete Biochemistry of Photosynthesis PSSA
Worksheet