1. Photosynthesis and
Cellular Respiration
Chapters 8 & 9

2. 8.1 Energy and Life
Chemical Energy and ATP
Where do we get our energy?


Ultimately all energy in living systems needed
for metabolism comes from the sun.
That energy is transferred first to organic
compounds (glucose)

then to energy storing molecules (ATP).

3. 
One of the most important compounds that
cells use to store and release energy is
adenosine triphosphate (ATP).

4. ATP Releases energy when a
phosphate group is removed
phosphate removed
Tri = 3
Di = 2

5. 
Organisms that use photosynthesis to make organic
compounds (food) are called autotrophs.

Examples: plants, algae, some bacteria

6. 
Organisms that must get energy from food are
called heterotrophs.


Cellular respiration converts the food we eat into
energy (ATP and heat).
ATP delivers energy wherever energy is needed in
the cell.

7. 8.2 Photosynthesis: An Overview

When you eat, you can trace the origin of your
food back to the sun.
Photosynthesis Song

8. Chlorophyll and Chloroplasts
Why do we see leaves as green?
Pigments, light absorbing substances,
absorb only certain wavelengths of light
and reflect all others.
 Chlorophyll, the primary pigment in
plants absorbs red, and blue-violet
light, and reflects green and some
yellow.

9. 


Photosynthesis takes place in the chloroplasts
of plant cells.
Chloroplasts contain stacks of thylakoids
(grana)
The fluid within the chloroplast is known as
the stroma.
Cytoplasmic Streaming of chloroplasts
grana (thylakoids)
chloroplast
stroma

10. Overview of photosynthesis:
 Stage 1: Light Dependent Reactions (energy
is captured from sunlight)
 Stage 2: Light Dependent Reaction (electron
transport chain – light energy converted to
ATP)
 Stage 3: Light Independent Reaction/Calvin
Cycle (ATP is used to produce glucose)
Photosynthesis equation:
light
6CO2 + 6H2O → C6H12O6 + 6O2

11. granum (stack of thylakoids)
chloroplast
chloroplast
su
nli
gh
t
6H2O
6O2
energy
thylakoid
Contains chlorophyll
6CO2
stroma (fluid outside the thylakoids)
1 six-carbon sugar
C6H12O6
Calvin Cycle/light-dependent
reactions (stroma)

12. Review Questions



Describe the importance of photosynthesis to
all forms of life.
Describe the role of light, and chlorophyll in
photosynthesis?
How does ATP store and release energy?

13. Factors Affecting Photosynthesis (8.3)
Light
 The rate of photosynthesis increases as light
intensity increases until all the pigments are
being used.
 The reactions cannot increase beyond this
point

14. Temperature
 Temperatures too high or too low can affect
the enzymes assisting the chemical reactions

15. Water
 A shortage of water can slow or even stop
photosynthesis.

Plants that live in dry conditions have adaptations
to live in these conditions
Waxy coatings on their leaves
 Biochemical adaptations (C4 or CAM)


16. 9.1 Cellular Respiration: An
Overviewenergy in food as
 Cellular respiration releases the
ATP when oxygen gas is present.
 Occurs in the mitochondria of a cell
Equation:
C6H12O6 + 6O2 → 6CO2 + 6H2O + energy
mitochondrion
animal cell

17. Overview of Cellular Respiration
Step 1 – Glycolysis

Begins with sugar (glucose) and makes pyruvic
acid and ATP.
Step 2 – Kreb’s Cycle

When O2 is present, breaks pyruvic acid down
releasing CO2 and ATP.

Sends energy to the next step
Step 3 – Electron Transport Chain

Uses O2 and energy to make ATP and releases
water.

18. Glycolysis:
1
Takes place in the
cytoplasm
Starts with sugar
mitochondrion
mitochondrion
ATP
Kreb’s Cycle
pyruvic acid
and
6CO2
2
energy
energy
ATP
6O2
and
and
Electron Transport
Chain
6H 2O

20. Comparing Photosynthesis and
Cellular Respiration

Reactions work together:
Photosynthesis
Energy
Cellular Respiration
Sun → organic
compounds
Organic Compounds →
ATP
Oxygen Releases O2
Uses O2
Carbon Uses CO2
Dioxide
Releases CO2
Space Plants Video

21. 9.3 Fermentation
If oxygen is not present…..

Fermentation occurs (anaerobic).



Without O2, releases energy from food producing
ATP
Lactic acid fermentation – causes muscle burn
Achoholic fermentation – produces ethyl alcohol and
CO2. Yeast is a common organism which uses this
process.

Used to make foods such as bread, cheese, and yogurt

22. Review Questions


In what type of cells does cellular respiration
take place?
What will occur if no oxygen is present?