Photosynthesis light 6CO2 6H2O C6H12O6 6O2

1
Photosynthesis(light)6CO2 6H2O ? C6H12O6
6O2

• Synthesizing carbohydrates through a series of
  Biochemical Reactions

2
Figure 7.18 The chloroplast, site of
photosynthesis
3
Key structures INSIDE chloroplasts

• Thylakoid saclike structure in chloroplasts
  made of photosynthetic membranes these sacs
  are made up of lipid bilayers
• Granum a stack of thylakoids
• Stroma region outside of the thylakoid
  membranes
• Chlorophyll molecules are embedded in the
  thylakoid membranes.

4
Figure 10.9 Location and structure of
chlorophyll molecules in plants
The pigment molecules have a large head section
that is exposed to light in the surface of the
membrane the hydrocarbon tail anchors the
pigment molecules into the lipid bilayer.
5

• There are 2 stages in Photosynthesis
• 1. Light dependent reactions
• 2. Light independent reactions
• (Calvin Cycle)

6
Figure 8-7 Photosynthesis An Overview
Section 8-3
Chloroplast
Chloroplast
NADP
ADP P
Light- Dependent Reactions
Calvin Cycle
ATP
NADPH
Go to Section
7
2 stages of Photosynthesis

• Stage 1 Light dependent reactions
• require presence of light
• occur in thylakoids of chloroplasts
• use energy from light to produce ATP and
  NADPH (a temporary, mobile energy source that
  helps store even more energy)
• oxygen gas is produced as a by-product

8
Figure 10.4 An overview of photosynthesis
cooperation of the light reactions and the Calvin
cycle (Layer 1)
9
Figure 10.4 An overview of photosynthesis
cooperation of the light reactions and the Calvin
cycle (Layer 2)
10

• Photosystem II -- Light is absorbed by pigment.
  Energy is transferred to e-, which go into ETC
  (electron transport chain.) Hydrolysis breaks
  water up into e-, H, and O2
• ETC moves H ions from stroma into inner
  thylakoid.
• Photosystem I -- light is absorbed by pigments,
  energy goes to e-, NADPH is formed
• Hydrogen movement makes inside positively
  charged.
• As H diffuses through ATP synthase, ADP is made
  into ATP.

Figure 8-10 Light-Dependent Reactions
Section 8-3
Hydrogen Ion Movement
Chloroplast
Photosystem II
ATP synthase
Inner Thylakoid Space
Thylakoid Membrane
Stroma
Electron Transport Chain
Photosystem I
ATP Formation
Go to Section
11
Figure 10.11 How a photosystem harvests light
Chlorophyll a
12
Figure 10.13 A mechanical analogy for the light
reactions
13

• Stage 2 Light Independent Reactions
• do not require light also known as the
  Dark Reactions or the Calvin Cycle
• take place in the stroma of chloroplasts
• ATP and NADPH produced during light
  dependent reactions are used to make glucose

14
Figure 10.x1 Melvin Calvin
15
Figure 10.4 An overview of photosynthesis
cooperation of the light reactions and the Calvin
cycle (Layer 3)
16
Figure 8-11 Calvin Cycle

• 6 CO2s combine with 6 5-C molecules make 12
  3-C molecules
• C. 2 of the 12 3-C molecules are made into
  glucose
• D. Other 10 3-C molecules are broken down into
  six 5-C molecules to start cycle over

Section 8-3
CO2 Enters the Cycle
Energy Input
ChloropIast
5-Carbon Molecules Regenerated
6-Carbon Sugar Produced
Sugars and other compounds
Go to Section
17
Factors affecting Photosynthesis

• Amount of water available too little, stop
  photosynthesis
• Temperature best between Oo Celsius and 35o
  Celsius (too high, damage enzymes too low, stop
  photosynthesis)
• Intensity of light up to a point, increasing
  light intensity increases rate of photosynthesis