The Light Independent Reactions

1
The Light Independent Reactions

• The Light Independent reactions take place in
  sunlight.
• If ATP and NADPH are provided, they can be
  carried out without light (dark reactions).
• Like the light-dependent reactions they occur in
  the chloroplast but in the area surrounding the
  thylakoid membranes called the stroma.

2
The Light Independent Reactions

• The light independent reactions are also called
  the Calvin Cycle.
• This is because the reactions form a cycle and
  were discovered by Melvin Calvin.
• The Calvin cycle reactions use carbon dioxide
  (CO2) along with ATP and NADPH, which were formed
  by the light reactions, to produce PGAL.

3
The Light Independent Reactions

• PGAL (phosphoglyceraldehyde) is a molecule that
  is used to make glucose and other organic
  compounds (e.g., amino acids lipids).
• Glucose is made because it is more stable and
  can store more energy than either NADPH or ATP.
• To summarize, the light independent reactions
  provide the raw materials that are used to make
  most of what the cell needs to survive.

4
Calvin Cycle
5
The Light Independent Reactions
6
Light Reactions
H2O

• produces ATP
• produces NADPH
• releases O2 as a waste product

Energy Building Reactions
NADPH
ATP
O2
7
Calvin Cycle

• builds sugars
• uses CO2, ATP NADPH
• recycles ADP NADP
• back to the light-dependent reactions to make
  more ATP NADPH

CO2
ADP
NADP
SugarBuilding Reactions
NADPH
ATP
sugars
8
Photosynthesis
9
The Light Independent Reactions
10
What factors affect photosynthesis?

• 1. Temperature Photosynthetic enzymes function
  best between 0C (32F) and 35C (95F).
• 2. Light High light intensity increases the rate
  of photosynthesis, up to a certain level.
• 3. Water A shortage of water can slow or even
  stop photosynthesis.

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GLYCOLYSIS AND RESPIRATION

• glucose (sugar) oxygen carbon dioxide
  water
• C6H12O6 6O2 6CO2
  6H2O
• Energy stored in chemical bonds of glucose can
  be used when the bonds are broken.
• Cells capture the energy of glucose through the
  processes of glycolysis and respiration.

12
GLYCOLYSIS

• Glycolysis, which means glucose breaking, is the
  first phase in the break down of glucose.
• It is an anaerobic phase because it takes place
  without oxygen.
• It takes place in the cytoplasm of the cell.
• It requires two molecules of ATP to start the
  process.

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GLYCOLYSIS

• During the process, the 6-carbon glucose is
  split into two 3- carbon PGAL molecules.
• The two PGAL molecules are then transformed into
  two molecules of pyruvic acid.
• During the process, 4 molecules of ATP are
  produced, resulting in a net gain of 2 ATP.
• Also, 2 NADH molecules are produced.
• NADH is an energy-storing compound.

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GLYCOLYSIS

• Summary
• In glycolysis, glucose is changed by enzymes
  into different molecules one step at a time
  through a series of chemical reactions.
• The initial glucose molecule is broken down and
  transformed into the final product, which is two
  molecules of pyruvic acid.

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GLYCOLYSIS