HS Biology class photosynthesis notes

1. Photosynthesis

2. Autotrophs vs. Heterotrophs
Autotroph
 Make their own
food
Example: Plants
Heterotroph
 Obtain energy from
foods they eat
Example: Animals,
fungi

3. Autotrophs
Photosynthesis occurs within:
Some bacteria
Algae
Within leaves of plants
does NOT happen in ALL cells

4. Chemical Energy
Energy – the ability to do work
Adenosine Triphosphate (ATP)
Adenine
Ribose
3 phosphate groups
ADP + P
Adenosine diphosphate + phosphate

5. Chemical Energy
=
Adenosine
Triphosphate
(ATP)

6. Photosynthesis
The process of creating sugar
from CO2.
Consumes H2O and is powered
by light.

7. Photosynthesis Equation
Light
CO2 + H2O  C6H12O6 + O2
carbon dioxide + water  sugars + oxygen
6 6 6

8. Electromagnetic Spectrum

9. Absorption of Light by
Chlorophyll a and Chlorophyll b

10. Light and Pigment
Plants gather the Sun’s energy
with light absorbing molecules
called pigments
Chlorophyll (Green)
chlorophyll a and chlorophyll b

11. Chloroplast
Stroma - Liquid
Granum – stack
of thylakoids
Thylakoid – contains chlorophyll

12. Photo Synthesis
Light To make or create

13. Photosynthesis Part I:
Light Dependent Reactions
Location: Thylakoid Membrane

14. Light-Dependent Reactions

15. Light-Dependent Reactions
Location: Thylakoid Membrane
1. Photosystem II
 Light energy absorbed by electrons
and increases their energy level
 Enzymes break up water molecules
into:
 2 electrons
 2 hydrogen ions
 1 oxygen atom

16. Light-Dependent Reactions
Location: Thylakoid Membrane
2. Electron Transport Chain
 High-energy electrons move
hydrogen ions from the stroma
into the inner thylakoid space

17. Light-Dependent Reactions
Location: Thylakoid Membrane
3. Photosystem I
Uses energy from light to re-energize
the electrons.
NADP+ picks up electron and 2 H+
ions
Produces NADPH

18. Light-Dependent Reactions
Location: Thylakoid Membrane
4. Hydrogen Ion Movement
 Hydrogen ions move
across the thylakoid
membrane making the
inside positively charged

19. Light-Dependent Reactions
Location: Moves from Thylakoid to Stroma
5. ATP Formation
Hydrogen ions pass through ATP
synthase (protein)
Energy is converted from ADP
to ATP

21. Photosynthesis Part II:
Light Independent Reactions
a.k.a. Calvin Cycle
Location: Stroma

22. Calvin Cycle
Uses CO2, ATP and
NADPH to produce
high energy sugars

23. Calvin Cycle
Location: Stroma
1. Carbon Fixation
6 CO2 combines with a
five-carbon sugar
Enzyme breaks down to
12 three-carbon molecules

24. Calvin Cycle
Location: Stroma
2. Energy Input
ATP is broken down giving each
three-carbon molecule a
phosphate
NADPH gives up electrons to
provide more energy

25. Calvin Cycle
Location: Stroma
3. Sugar Production
2 three-carbon molecules exit
cycle to be used by the plant
10 three-carbon molecules are
recycled

26. Calvin Cycle
Location: Stroma
4.5-Carbon Molecule Regeneration
10 three-carbon molecules are
converted back into 6 5-carbon
molecules to be used in the next
cycle
6 ATP molecules are used to complete
this process

29. Factors Affecting Photosynthesis
Water
Plants in dry conditions have a waxy coating
on the leaves that reduce water loss
 Temperature
Photosynthesis depend on enzymes that
function best between 0oC and 35oC
 Light Intensity
Increasing light intensity increases the rate
of photosynthesis
However, a plant has a maximum rate of
photosynthesis that can be reached