Photosyntehsis PPT [Autosaved] Version two

This ppt contains the steps of photosynthesis including and the light and dark reaction

1. PHOTOSYNTHESISPHOTOSYNTHESIS

2. I. Introduction to photosynthesis
•From the Greek
PHOTO = produced by light
SYNTHESIS = a whole made of parts put
together.
Definition: PHOTOSYNTHESIS is the process
whereby plants, algae, some bacteria,
use the energy of the sun to synthesize organic
compounds (sugars) from inorganic compounds
(CO
2 and water).

3. WHY IS PHOTOSYNTHESIS
SO IMPORTANT?
PHOTOSYNTHESIS is one of the most
important biological process on earth!
• Provides the oxygen we breathe
• Consumes much of the CO
2
• Food
• Energy
• Fibers and materials

4. GENERAL FORMULA FOR
PHOTOSYNTHESIS
light
6 CO
2
+ 12 H
2
O ---------> C
6
H
12
O
6
+ 6 O
2
+ 6 H
2
O
pigments, enzymes
* *
• Oxygen on earth allowed for the evolution of aerobic
respiration and higher life-forms.
• Respiration: extracting energy from compounds (sugars)
C
6
H
12
O
6
+ O
2
 6 CO
2
+ ATP

5. II.PROPERTIES OF LIGHT
Virtually all life depends on it!
•Light moves in waves, in energy units
called a photon
• Energy of a PHOTON is inversely
proportional to the wavelength
• Visible light is in between UV and IR light
on the spectrum of light

6. Visible light contains just the right amount of
energy for biological reactions

7. Light is absorbed by pigments
•The primary pigment for photosynthesis is
chlorophyl
•It absorbs red and blue light but, not green
(green light is reflected!)
Absorption spectrum
of chlorophyll a

8. Accessory pigments:
Other pigments in the plant that contribute a
plants color
Help transfer some energy to chlorophyll
Help the plant capture more light energy for
photosynthesis

9. Where does photosynthesis occur?

10. The plant cell

11. Chloroplast structure
•Football shaped
•Double membrane
•Stroma
•Thylakoid
membrane
•Grana (stacks)
•Lumen
(inside thylakoid)
stroma
Grana
thylakoids
lumen

12. Inside a Chloroplast
•Remember: Structure correlates to function!

13. Overview of photosynthesis:
Note: The Light and “Dark”or Carbon
reactions happen at different sites in the
chloroplast
LIGHT
REACTIONS
(Thylakoids)
“DARK” or CARBON
REACTIONS
(Stroma)
light
ATP
NADPH
(ENERGY)
H2O
O2
(OXYGEN GAS)
CO2
C6H12O6
(GLUCOSE)

14. IV. The Light Reactions
1. Light Dependent
2. Occur in the thylakoid membrane of
chloroplast
4. Use light energy (photons) to generate two
chemical energy compounds: ATP &
NADPH
3. Water is split into oxygen gas (O
2) and H
+

15. IV. The Dark Reactions
1. Light Independent
2. Occur in the Stroma of chloroplast is also
called the Calvin cycle
4. Uses ATP and NADPH to provide the
energy to create glucose
3. Takes Carbon dioxide (CO2) and combines
them to create glucose

16. Sequence of events in the Light Reactions
STROMA
LUMEN (inside thylakoid)
PS II PS I
ATPSe
-
2 H
2
O
O
2
+ 4 H
+
(gas) (protons)
NADP
+
+ H
+
NADPH
ADP + P
i
ATP
H
+

17. Summary of Dark Reactions

18. VI. Summary of Photosynthesis:
1.Light energy absorbed by chlorophyll a
drives the reactions of photosynthesis.
2. Converts light energy into chemical
energy to make organic compounds.
3. CO
2 and H
2O used to produce
C
6H
12O
6 (glucose) and O
2 (gas).

19. 4. Light Reactions occur in thylakoids of the
chloroplasts; ATP and NADPH are formed;
water is split to O
2
(gas) and protons.
5. Carbon Reactions occur in stroma – Calvin
Cycle fixes CO
2 to produce C
6H
12O
6 (glucose).
6. Low efficiency, about 1- 4% in C-3 plants.
7. Nevertheless, PHOTOSYNTHESIS is still
the most important biological process on
earth!

20. Importance of photosynthesis and the
impact that it has in all our lives.
Without photosynthesis, virtually all
plants and animals would become
extinct.

21. Respiration, Energy & Carbon Cycle
•The way living organisms obtain energy is through
Cell respiration
•It is a process where an organism
Takes Glucose and creates ATP from it
•Is the opposite of photosynthesis

22. RESPIRATION
•Process of making energy of food available in the
cell…
•Involves breaking down
•Complicated molecules  into simple molecules
(C
6H
12O
6, sugars)(CO
2, water)
This Releases Energy the Body uses to create ATP

23. RESPIRATION
The energy held by complicated molecules is held
temporarily as ATP (energy currency)
C
6
H
12
O
6
+ 6 O
2
 6CO
2
+ 6 H
2
O + 36 ATP
(glucose) (energy)
Respiration occurs mainly in
Mitochondria and Cytoplasm

24. Stages of Respiration
Cellular Respiration has three main stages:
•Glycolysis
•Krebs Cycle
•Electron transport system

25. 3 Stages of cellular respiration
•Glycolysis: Splitting of glucose – 2 net ATP generated
•Krebs Cycle: Energy of glucose molecule is harvested
as ATP (2) – it occurs in the mitochondria (matrix)
•Electron Transport System: also happens in the
mitochondria, more ATP are generated (32).
•For each glucose molecule, total ATP = 36
•Only 39% efficient, rest is lost as heat.

26. Photosynthesis Respiration
•Reaction: CO2+H2O+sunC6H12O6+O2+H2O C6H12O6+O2CO2+H2O+36ATP
•Reactants: Carbon dioxide, water, sun Glucose, oxygen
•Products: Glucose Energy
•By-products: Oxygen Carbon dioxide, water
•Cellular location: Chloroplasts Cytoplasm, mitochondria
•Energetics: Requires energy Releases energy
•Chemical paths: Light reactions & Glycolysis, Krebs cycle
Calvin cycle & Electron Transport Syst.
•Summary: Sugar synthesized using Energy released from
energy from the sun sugar breakdown
Chapter 4: Table 4.1, p. 63

27. Photosynthesis and respiration
•Photosynthesis and respiration are
complimentary reactions…

28. PHOTOSYNTHESIS RESPIRATION

CO
2
+ H
2
O  O
2
+ SUGARS SUGARS + O
2
 H
2
O + CO
2

PLANTS, PLANTS,
ALGAE, ALGAE,
BACTERIABACTERIA
MOST LIVING
ORGANISMS
H
2
O H
2
O
O
2
O
2CO
2
CO
2
SUGARS
Sunlight
energy
USEFUL CHEMICALUSEFUL CHEMICAL
ENERGY (ATP)ENERGY (ATP)

29. ENERGY: ability to do work
Newton’s First Law of Thermodynamics:
“Energy cannot be created or destroyed, it
can only be transformed from one form
to another”
•Once a cell has used energy to do work, it cannot
be used again by any organism.
(1701)

30. ENERGY
ENERGY FLOW IS LINEAR
Sun  Earth Producers 1
o
consumers  2
o
consum
heat resp, heatresp, heat resp, heat
Energy flows into ecosystem from the sun
Energy travels in a straight line by way of
food chains.

31. ENERGY
However, much energy is lost as heat along the
way – as a result of respiration.
Approximately 90% energy is lost on each step!
•Newton’s Second Law of
Thermodynamics:
“In any transfer of energy there is always a
loss of useful energy to the system, usually in
the form of heat”

32. Food Chains
•(Not referring to SHOPPERS, SAFEWAY or GIANT !!!)
•Food chains demonstrate linear nature of energy
•Producers are the base of the food chain, they
include photosynthetic organisms like:
•Plants
•Algae
•Certain bacteria

33. Food chains
•Primary consumers – all plant
eaters (herbivores).
•Secondary consumers –
Eat primary consumers,
(carnivores)

34. Food chains
•Decomposers – obtain energy by breaking
down remaining organic material of the
other members of the food chain.
•Fungi and bacteria.

35. Matter
•All important elements move in cycles;
Environment Organisms
Cycles called biogeochemical cycles:
Water cycle
Carbon cycle
Nitrogen cycle

36. The Carbon Cycle
•Carbon from the atmosphere (CO
2) enters the
biosphere by way of plants!
–CO
2 used in photosynthesis
–Carbon moves into food chain
•Carbon is released to the physical environment by
respiration
–Release CO
2 during respiration
–Amount CO
2
fixed in photosynthesis = the amount
released by respiration

37. Carbon Cycle
•Carbon moves from atmosphere to plants to
animals and back to atmosphere.