Photosynthesis (Basic Overview)

2. Remember:
• Organisms that make their own food are
called autotrophs.
• Organisms that can NOT make their
food are called heterotrophs.

3. What do all plants have in
common?
• Cell wall (cellulose)
• Most plant cells contain
chlorophyll
1.Photosynthesis -
process where plants
use chlorophyll and
light to make food.
2.Chlorophyll is found in
a cell structure called a
chloroplast.
• Most of the space is taken
up by a large, membrane-
bound structure called a
central vacuole, which
regulates water content.

4. Use this
handout to take
notes for the
next 2 slides.

5. A plant needs four basic things in order to do
photosynthesis:
1. Water (from the ground)
2. CO2 (from the air)
3. Light (energy)
• white light
• collected by the chloroplasts
4. Chlorophyll (pigment molecule)
• Absorbs light
Photosynthesis

7. What does the plant do with this?
• When the plant gets all of things together
it produces glucose (food)
• can then be distributed throughout the
plant.
• produces O2 as a by-product.
• Heterotrophs can’t do this because they
lack:
• chlorophyll.

8. What is the reaction for
photosynthesis?
Carbon Dioxide + Water Glucose + Oxygen
Light
6CO2 + 6H2O C6H12O6 + 6O2
Chlorophyll

9. The Process:
There are 2 stages of
photosynthesis:
1.Light-dependent
• In Thylakoid of
CHLOROPLAST
2. Light independent
• In Stroma of
CHLOROPLAST
• These two stages
reflect the literal
meaning of the term
photosynthesis:
photo = use light
synthesis = to build/make

10. Photosynthesis Summary: 2 Stages
sunlight
required
Energy from sunglight
trapped in bonds of
ATP
Light Reactions
occurs with or
without
sunlight
ATP
used to make
carbohydrates
Dark Reactions
Photosynthesis

11. Structures
of
Photosynthesis:
Where does
this happen?

13. Leaves
• Key parts:
a. stoma
b. mesophyll cells
c. veins
Stoma
Mesophyll
Cell
Chloroplast

14. Stomata (stoma)
• Pores in a plant’s cuticle through which water
vapor and other gases are exchanged
between the plant and the atmosphere.
Guard CellGuard Cell
Carbon Dioxide
(CO2)
Oxygen
(O2)

15. Mesophyll Cell
Cell Wall
Nucleus
Chloroplast
Central Vacuole

16. Chloroplast
• Chloroplast, a structure in the cells of
plants (and algae) where photosynthesis
takes place.
• They occur most abundantly in mesophyll
cells, where they can orient themselves to
light
• They contain saclike photosynthetic
membranes:
– Thylakoids
• Stacked to form Grana

17. Chloroplast
• Organelle where photosynthesis takes place.
GranumThylakoid
Stroma
Outer Membrane
Inner Membrane

19. Thylakoid
Thylakoid Membrane
Thylakoid Space
Granum
chlorophylll

20. A closer look at CHLOROPHYLL
• Molecules of
chlorophyll are
attached to the
thylakoid membranes.
• The light energy
captured by the
chlorophyll is
converted ATP.
– Biochemical pathway

21. • When the light is absorbed, energy is
absorbed too.

23. Visible Spectrum
• The visible spectrum is the light that you
can see. It contains ALL of the colors.

24. • Chlorophyll
pigments harvest
energy (photons) by
absorbing certain
wavelengths (blue-
420 nm and red-660
nm are most
important).
• Plants are green
because the green
wavelength is
reflected, not
absorbed.

27. Dark
Reactions
(aka. Calvin
Cycle
Thylakoid
Stroma

29. Veins = Vascular Bundles
• Veins carry water and
nutrients.
• Embedded in leaf
• Occur throughout the
rest of the plant
• Vein = a bundle of
long tubes
– Xylem
– Phloem

30. For Photosynthesis:
(liquid)
Glucose
(dissolved)