PHOTOSYNTHESIS
by: Mihael Fofic
Curriculum Expectations:
C2.1 – use appropriate terminology related to metabolism.
C2.3 – conduct a laboratory investigation of the process of photosynthesis to identify the products of the process, interpret the qualitative observations, and display them in an appropriate format.
C3.2 – explain the chemical changes and energy conversions associated with the process of photosynthesis.
*[C3.3 – use the laws of thermodynamics to explain energy transfer in the cell during the processes of cellular respiration and photosynthesis.]
*[C3.4 – describe, compare and illustrate the matter and energy transformations that occur during the processes of cellular respiration and photosynthesis, including the roles of oxygen and organelles such as mitochondria and chloroplasts.]
*These expectations will be covered in a summary lesson comparing cellular respiration and photosynthesis.
LEARNING GOALS:
Students will:
C2.3 – conduct a laboratory investigation of the process of photosynthesis to identify the products of the process, interpret the qualitative observations, and display them in an appropriate format.
C3.2 – explain the chemical changes and energy conversions associated with the process of photosynthesis.
*[C3.3 – use the laws of thermodynamics to explain energy transfer in the cell during the processes of cellular respiration and photosynthesis.]
*[C3.4 – describe, compare and illustrate the matter and energy transformations that occur during the processes of cellular respiration and photosynthesis, including the roles of oxygen and organelles such as mitochondria and chloroplasts.]
*These expectations will be covered in a summary lesson comparing cellular respiration and photosynthesis.
LEARNING GOALS:
Students will:
- Differentiate between heterotrophs and autotrophs.
- List various organisms that can carry out Photosynthesis.
- Describe the role of chlorophyll in Photosynthesis.
- Label and identify the parts of a chloroplast.
- Compare the chemical formula for Cellular Respiration to that of Photosynthesis.
- List the three main stages of Photosynthesis.
- Describe what is accomplished in each stage of Photosynthesis, and how these stages are interconnected.
- Describe the key roles of photoexitation and redox reactions in Photosynthesis.
- Differentiate between noncyclic electron flow and cyclic electron flow
- Describe the steps involved in the Calvin Cycle
- Identify and describe similarities and connections between cellular respiration and photosynthesis
PHOTOSYNTHESIS OVERVIEW
WHAT IS AN AUTOTROPH?
An autotroph is an organism that can produce energy-containing organic compounds from simple inorganic materials present in its surroundings.
ORGANISMS THAT CAN CARRY OUT PHOTOSYNTHESIS:
Prokaryotic Autotrophs -- Cyanobacteria
Eukaryotic Autotrophs -- Plants, Algae, and some Protists
An autotroph is an organism that can produce energy-containing organic compounds from simple inorganic materials present in its surroundings.
- Organisms that can accomplish this using energy from sunlight (Photosynthesis) are called photoautotrophs
ORGANISMS THAT CAN CARRY OUT PHOTOSYNTHESIS:
Prokaryotic Autotrophs -- Cyanobacteria
Eukaryotic Autotrophs -- Plants, Algae, and some Protists
What do all of these organisms share in common?
The green pigment CHLOROPHYLL
- Chlorophyll absorbs light and begins the process of Photosynthesis.
- Chlorophyll has a porphyrin ring (the light absorbing part of the chlorophyll molecule) with a long hydrocarbon tail.
There are numerous types of chlorophyll
- Two common types are chlorophyll a (blue-green) and chlorophyll b (yellow-green)
- Chlorophyll a and chlorophyll b differ in only one functional group, affecting the type of light energy that each molecule can absorb.
- Chlorophyll a is the primary light-absorbing pigment in all photosynthetic organisms; all other pigments are considered accessory pigments.
WHERE DOES PHOTOSYNTHESIS TAKE PLACE?
- Leaves, in particular, are the primary photosynthetic organ for most plants.
- Leaves maximize the surface area exposed to sunlight and limit the distance gases have to travel to reach the chloroplasts.
PHOTOSYNTHESIS, SUMMARIZED BY A CHEMICAL EQUATION:
- Since they are prokaryotes, Cyanobacteria contain chlorophyll within their cell membranes.
- Algae, photosynthetic protists, and plants contain chlorophyll within the membranes of specialized organelles called CHLOROPLASTS.
- Leaves, in particular, are the primary photosynthetic organ for most plants.
- Leaves maximize the surface area exposed to sunlight and limit the distance gases have to travel to reach the chloroplasts.
PHOTOSYNTHESIS, SUMMARIZED BY A CHEMICAL EQUATION:
*Note that the overall process is essentially the reverse of Cellular Respiration.
CHLOROPLAST STRUCTURE:
- Chloroplasts have an outer membrane and an inner membrane.
- The space inside a chloroplast is filled with a semiliquid material called stroma, with a system of membrane-bound sacs called thylakoids, some of which are stacked on top of one another to form grana.
- Thylakoid membranes contain chlorophyll molecules and electron transport chains.
THE 3 MAIN STAGES OF PHOTOSYNTHESIS:
The third stage is when the cell uses the carbon dioxide in order to make organic compounds. This reaction, requiring ATP and NADPH, is called carbon fixation. It happens in the stroma by going through a cycle of enzyme reactions called the Calvin Cycle.
- Capturing light energy.
- Using the captured energy to make ATP and NADP+ into NADPH (which is the energy transporting coenzyme).
- Using the free energy of ATP and reducing power of NADPH to make organic compounds like glucose, from CO2.
The third stage is when the cell uses the carbon dioxide in order to make organic compounds. This reaction, requiring ATP and NADPH, is called carbon fixation. It happens in the stroma by going through a cycle of enzyme reactions called the Calvin Cycle.
THE ROLE OF LIGHT IN PHOTOSYNTHESIS:
Only about 5% of the light energy that reaches the Earth’s surface, from the Sun, is used in Photosynthesis.
-- Chlorophylls a and b absorb photons in the blue-violet and red regions of the visible colour spectrum.
-- Most photosynthetic organisms look green to us humans because the wavelengths in the green part of the visible spectrum are either reflected or transmitted by these pigments.
-- Various wavelengths of visible light from 400nm to 700nm are absorbed by chlorophyll or one of the other accessory pigments (with some pigments absorbing certain wavelengths better than others), supporting photosynthesis.
Only about 5% of the light energy that reaches the Earth’s surface, from the Sun, is used in Photosynthesis.
- Embedded in the thylakoid membrane are clusters of photosynthetic pigments that absorb light energy, called photosystems.
-- Chlorophylls a and b absorb photons in the blue-violet and red regions of the visible colour spectrum.
-- Most photosynthetic organisms look green to us humans because the wavelengths in the green part of the visible spectrum are either reflected or transmitted by these pigments.
-- Various wavelengths of visible light from 400nm to 700nm are absorbed by chlorophyll or one of the other accessory pigments (with some pigments absorbing certain wavelengths better than others), supporting photosynthesis.
- The electrons (in the form of H atoms) that are needed to reduce NADP+ to NADPH are supplied by water molecules that enter the thylakoids from the stroma.
- ATP and NADPH are synthesized in the stroma, where the carbon fixation reactions occur.
PHOTOSYNTHESIS Learning ACTIVITIES
Spongelab - What plants need game
A game in which you can adjust the resources the plant receives and view the results. Learn what happens to plants in green light, or if different gases are present in the atmosphere.
spongelab - The Light Reaction Game
In this game, students control the placement of the protein complexes to harness light energy and make ATP and NADPH. Includes one tutorial level and three applied levels. Students are able to visualize the key steps, such as water splitting, electrons flowing, and the pumping of hydrogen ions across the membrane.
Spongelab - The Calvin cycle game
In the Calvin cycle game users play the system learning about the enzymes and components involved, and about the concept of 'recycling' as it pertains to a biochemical 'cycle.
The Calvin cycle or Calvin–Benson cycle or reductive pentose phosphate cycle is a series of biochemical redox reactions that take place in the stroma of chloroplasts in photosynthetic organisms. The net result of this cycle in the production of sugar.
Big idea Research Paper
Brochure Assignment
By clicking on the photo to your left, you can access your final assignment based on Photosynthesis.
For this assignment you will be researching Deforestation, with a focus on the role that the products of Photosynthesis have on Climate Change.
For this assignment you will be researching Deforestation, with a focus on the role that the products of Photosynthesis have on Climate Change.
GLOSSARY
- Absorption spectrum a graph illustrating the wavelengths of light absorbed by a pigment
- Autotroph an organism that can produce energy-containing organic compounds from simple inorganic materials present in its surroundings
- Calvin cycle a cyclic set of reactions occurring in the stroma of chloroplasts that fixes the carbon of CO2 into carbohydrate molecules and recycles coenzymes
- Carbon fixation the process of incorporating CO2 into carbohydrate molecules
- Chlorophyll the light-absorbing green-coloured pigment that begins the process of photosynthesis
- Grana (singular: granum) a stack of thylakoids
- Photosystem I a photosystem embedded in the thylakoid membrane containing chlorophyll P700
- Photosystem II a photosystem embedded in the thylakoid membrane containing chlorophyll P680
- Photosystems clusters of photosynthetic pigments embedded in the thylakoid membranes of chloroplasts that absorb light energy
- Porphyrin the light-absorbing portion of the chlorophyll molecule, containing a magnesium atom surrounded by a hydrocarbon ring
- Stroma the protein-rich semiliquid material in the interior of a chloroplast
- Thylakoids a system of interconnected flattened membrane sacs forming a separate compartment within the stroma of a chloroplast
Content: Di Giuseppe, M., Vavitsas, A., Ritter, B., Fraser D., Arora, A., and Lisser, B. (2003) Biology 12, Nelson Thomson Learning, Toronto.
Seeing Green Activity: Blake, L. (2002). McGraw-Hill Ryerson biology 12. Toronto: McGraw-Hill Ryerson.
Investigation of Leaf Stomata: Adapted from: http://www.biologycorner.com/worksheets/stomata.html
Interactive Activities: www.spongelab.com
Seeing Green Activity: Blake, L. (2002). McGraw-Hill Ryerson biology 12. Toronto: McGraw-Hill Ryerson.
Investigation of Leaf Stomata: Adapted from: http://www.biologycorner.com/worksheets/stomata.html
Interactive Activities: www.spongelab.com