Biology: Photosynthesis
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Photosynthesis

Videos: Photosynthesis

The paper Objectives:

After studying this material you should be able to:
1.Describe the energy transformations that occur in a chloroplast as light energy
is converted to the chemical bond energy of carbohydrate.
2.Draw a sketch of a chloroplast and indicate where these energy
transformations take place.
3.List the inputs (raw materials) and outputs (products) of the light reactions and
the Calvin Cycle.
4.Describe the role of ADP, ATP, NADP, and NADPH in linking the light
reactions and Calvin Cycle.
5.Describe the role of enzymes in the process of photosynthesis
6.List the environmental factors that would affect photosynthesis and use your
diagram from Objective 2 to indicate where and how they would have their
affect. (What is the relationship between stomatal opening, temperature, water
loss, and CO2 availability?)
7.Explain what the plant does with the carbohydrate that is produced by
photosynthesis.

Professor Govindjee's web page
Professor Govindjee, here at UIUC, is one of the leaders in the field of photosynthesis research and education. There are some web resources in his section on "Teaching Material on Photosynthesis, UIUC" for those who would like a little more detail and a different perspective.

THE PHOTOSYNTHETIC PROCESS Web Paper by U of I plant Biology professors John Whitmarsh and Govindjee

Webquest

Photosynthesis - The Basic Reaction

CO2 +

H2O +

---

Plants (Chloroplasts)
Light Energy

---

Simple
Sugars

+ O2

Chloroplast Structure

Outer membrane
Inner membrane systems
Thylakoid membranes
Thylakoid space (within the thylakoids)
Granum(a) (stack(s) of thylakoids membranes)
Stroma (the liquid area outside the thylakoid membranes)

Chloroplast diagram from The Photosynthetic Process by Dr.s John Whitmarsh and Govindjee

The Photochemical (Light) Reactions

Capture of light energy
Thylakoid membranes
Photosystems II and I
Chlorophyll and accessory pigments

Light absorbance and Photosynthesis
Whitmarsh & Govindjee fig. 5

Energy Transformations
flow of Electrons
Splitting of water molecules
Release of oxygen molecules
Accumulation of H+ in thylakoid Spaces
Reduction of NADP to NADPH
Production of ATP
ATP synthase
Powered by flow of H+
ADP + Phosphate --- ATP

Energy transformations in the thylakoid membranes. Whitmarsh & Govindjee fig. 3.

Animation of energy transformations during the light reactions
By Govindjee and Matej Lexa (This requires quite a bit of memory)

Summary of Light reactions: Light energy --- usable Chemical energy (ATP & NADPH)

The Biochemical Reactions: The Calvin Cycle

"Fixing" CO2
Cyclic series of enzyme reactions
Rubisco (the enzyme that fixes CO2)
Stomates and CO2 availability
Addition of CO2 to a 5 carbon compound
Production of Carbohydrate
Energy input from ATP (ATP --- ADP + Phosphate)
Addition of H+ and energy
Production of carbohydrates for storage, transportation, and biosynthesis
Recycling of 5 carbon compound to fix more CO2

Summary of Calvin Cycle:
Fig. 16 Whitmarsh & Govindjee

Energy of ATP and NADPH used to fix CO2 and produce carbohydrate.

Photosynthesis: Summary This is what it all distills down to:

Light Reactions
Light energy + H2O + Pigments	---O2 released
ADP+Phosphate+NADP--	ATP + NADPH--	ADP+Phosphate+NADP
CO2 + enzymes + RUBP--	Carbohydrate + enzymes + RUBP
Light Independent Reactions

Photosynthesis Problem Set 1 Photosynthesis Problem Set 1
The objectives of this problem set are to test your understanding of how light energy is
converted into different forms of chemical energy during photosynthesis, to review the
equations for the light reactions of photosynthesis, to study the pathway for electron transport
during cyclic and non-cyclic photophosphorylation, and to explore the mechanism for
coupling electron transport to ATP synthesis.

1.Chloroplast compartments
2.Energy source for ATP formation
3.Overall redox reaction
4.Result of electron transport
5.Overall energy source
6.Events during light reaction
7.Cyclic photophosphorylation
8.Equation for light reaction
9.Fate of excited pigment molecules
10.Overall result of photosynthesis
11.Photosystem II features

Photosynthesis Problem Set 2 Photosynthesis Problem Set 2
The objectives for this problem set are to review the location
and overall reactions of carbohydrate biosynthesis during
photosynthesis, including RUBISCO, and to understand the
difference between C3 and C4 plant leaf anatomy and
pathways for carbohydrate biosynthesis.

1.Calvin experiment
2.Calvin cycle reactions
3.Equation for dark reaction
4.Calvin cycle experiment
5.Basic equation of photosynthesis
6.Dark reactions
7.Products of the dark reactions
8.C4 plants
9.C4 photosynthesis