1. Chapter 4.1:4.2:4.3 Energy and Life

2. Energy is the ability to do work!
What is energy?
Energy is the ability to do work!

3. Sunlight is the main energy source for life on Earth.

4. 1. Cells use chemical energy in the form of a chemical compound called ATP, or adenosine triphosphate.
a. ATP contains:
i. A 5-carbon sugar called ribose
ii. A nitrogenous base called adenine
iii. Three phosphate groups
b. The bonds between the phosphate groups store and release energy

5. Energy is released when a phosphate group is removed.
ATP transfers energy from the breakdown of food molecules to cell functions.
Energy is released when a phosphate group is removed.
ADP is changed into ATP when a phosphate group is added.
phosphate removed

6. The chemical energy used for most cell processes is carried by ATP.
Molecules in food store chemical energy in their bonds.
Starch molecule
Glucose molecule

7. 3. ATP is the basic energy source of all cells

8. Organisms break down carbon-based molecules to produce ATP.
Carbohydrates are the molecules most commonly broken down to make ATP.
not stored in large amounts
up to 36 ATP from one glucose molecule
triphosphate
adenosine
diphosphate
tri=3
di=2

10. c. ATP is like a rechargable battery.
ADP
ATP
Energy
Energy
Adenosine diphosphate (ADP) + Phosphate
Adenosine triphosphate (ATP)
Partially
charged
battery
Fully
charged
battery

11. Chemical Energy and ATP: Storing Energy
Energy is stored in ATP
a. ADP, adenosine diphosphate, is similar to ATP but has two phosphate groups instead of three
b. When a cell has energy available, it can store small amounts by adding a phosphate to ADP making ATP

12. Using the energy
1. When a chemical bond between the 2nd and 3rd phosphates of ATP is broken, energy is released

13. Chemical Energy and ATP: Releasing Energy
2. ATP has enough energy to power a variety of cellular activities
A. active transport across the selectively permeable cell membrane
B. protein synthesis
C. muscle contractions
D. Propels flagella
E. Produces light in fireflies
Firefly
Escherichia coli bacterium with flagella

14. 4. ATP is a good short term energy storage that is recycled between ADP and ATP. Cells have only a small amount of ATP.
It is more efficient for cells to store energy as glucose.
When cells need energy they make ATP from ADP using energy from glucose.

15. Fats store the most energy.
80 percent of the energy in your body
about 146 ATP from a triglyceride
Proteins are least likely to be broken down to make ATP.
amino acids not usually needed for energy
about the same amount of energy as a carbohydrate

16. ADP vs. ATP

17. C A B What is the name of the molecule above?
What is the name of the part of the molecule labeled:
A? ___________________________
B? ___________________________
C? ___________________________
adenine
ribose
3 phospates

18. How does a cell get energy from this molecule?B
How does a cell get energy from this molecule?
By breaking the bond between the 2nd and 3rd phosphate. This releases the energy!!

19. What is photosynthesis?
The process in which plants use the energy of the sun to convert water and carbon dioxide into high-energy carbohydrates (sugars and starches) and oxygen (a waste product).

20. Chlorophyll is a molecule that absorbs light energy.
chloroplast
leaf cell
leaf
In plants, chlorophyll is found in organelles called chloroplasts.

21. Photosynthesis in plants occurs in chloroplasts.
Photosynthesis takes place in two parts of chloroplasts.
grana (thylakoids)
stroma
chloroplast
stroma
grana (thylakoids)

22. The light-dependent reactions capture energy from sunlight.
take place in thylakoids
water and sunlight are needed
chlorophyll absorbs energy
energy is transferred along thylakoid membrane then to light-independent reactions
oxygen is released

23. The light-independent reactions make sugars.
take place in stroma
needs carbon dioxide from atmosphere
use energy to build a sugar in a cycle of chemical reactions

24. The equation for the overall process is:
6CO2 + 6H2O  C6H12O6 + 6O2
C6H12O6
granum (stack of thylakoids)
thylakoid
sunlight
1 six-carbon sugar
6H2O
6CO2
6O2
chloroplast 1 2 4 3
energy
stroma (fluid outside the thylakoids)

25. Light Energy
Chloroplast
CO2 + H2O
Sugars + O2

26. Light and Pigments Photosynthesis requires: water carbon dioxide light
chlorophyll (a pigment molecule in chloroplasts; two types)
chlorophyll a
chlorophyll b

27. ROYGBIV
Sunlight is perceived as white light, but is really a mixture of different wavelengths of light (like a rainbow). The visible light we can see is a very small portion of the electromagnetic spectrum.
Red Orange Yellow Green Blue Indigo Violet
Red: long wavelength, less energy
Violet: Short wavelength, high energy

28. Pigments are molecules that absorb light at different wavelengths.
Chlorophyll absorbs light in the visible spectrum, except the green wavelengths.
Green light is reflected by the leaves making plants look green.
The high energy that is absorbed makes photosynthesis work.

29. Factors affecting photosynthesis
Shortage of water
Temperature (0-35 degrees Celsius)
Intensity of light

30. Inside a Chloroplast Photosynthesis takes place inside chloroplasts.
Chloroplasts contain:
thylakoids: saclike photosynthetic membranes containing pigments
grana (singular: granum): stacks of thylakoids
stroma: region of chloroplasts outside of the thylakoid membranes
inner membrane
outer membrane

32. Photosystem II captures and transfers energy.
chlorophyll absorbs energy from sunlight
energized electrons enter electron transport chain
water molecules are split
oxygen is released as waste
hydrogen ions are transported across thylakoid membrane

33. Electron Carriers
Sunlight excites electrons in chlorophyll, causing them to gain energy.
An excited electron is like a hot coal, and cannot be easily carried from one place to another- a protein called an electron carrier is required to transport excited electrons.

34. NADP+ + 2 electrons + H +  NADPH
Electron transport: An electron carrier molecule can accept a pair of high-energy electrons and transfer them to another molecule.
Electron transport chain: Series of electron carriers
Example: NADP+ (nicotinamide adenine dinucleotide phosphate)
NADP+ + 2 electrons + H +  NADPH
NADPH can carry high-energy electrons to other chemical reactions in the cell that need energy

35. Photosystem I captures energy and produces energy-carrying molecules.
chlorophyll absorbs energy from sunlight
energized electrons are used to make NADPH
NADPH is transferred to light-independent reactions

36. Light Dependent Reactions
The light-dependent reaction splits water, produce oxygen gas as waste, and converts ADP and NADP+ into ATP and NADPH.

37. The second stage of photosynthesis uses energy from the first stage to make sugars.
Light-independent reactions occur in the stroma and use CO2 molecules.

38. A molecule of glucose is formed as it stores some of the energy captured from sunlight.
carbon dioxide molecules enter the Calvin cycle
energy is added and carbon molecules are rearranged
a high-energy three-carbon molecule leaves the cycle

39. A molecule of glucose is formed as it stores some of the energy captured from sunlight.
two three-carbon molecules bond to form a sugar
remaining molecules stay in the cycle

40. Light Dependent Reactions
Light hits Photosystem II in the thylakoid membranes. Two electrons are excited and these excited electrons are passed onto the electron transport chain
To replace the lost electrons, the thylakoid membrane obtains low-energy electrons by splitting water 2H2O  4H+ + O2 + 2 e-
The O2 is released as waste
The hydrogen ions (4H+) are released inside the thylakoid membrane

41. Light Dependent Reactions
2. Electron transport chain (ETC)
Electrons are passed from Photosystem II to Photosystem I from one electron carrier to the next until they reach Photosystem I
Energy from the electrons is used by the electron carriers in the ETC to force H+ ions from the stroma into the inner thylakoid space- build up of H+ will be used to drive ATP synthase

42. Light Dependent Reactions
3. Light hits Photosystem I
Pigments in Photosystem I use energy from light to energize two electrons, making them high-energy
They are passed to NADP+ Reductase which catalyzes the reaction of NADP+ take combining with the high-energy electrons and hydrogen ions (H+) to become NADPH

43. Light Dependent Reactions
4. Hydrogen Ion Movement
The inside of the thylakoid membrane fills up with positively charged hydrogen ions (H+) as electrons are passed from Photosystem II to I
ATP synthesis
The thylakoid membrane contains a protein called ATP synthase that spans the membrane and allows H+ ions to pass through it
As H+ ions pass through ATP synthase, the protein rotates and binds ADP and a phosphate group to produce ATP.

44. Light-independent reactions (The Calvin Cycle)
During the Calvin cycle, plants use ATP and NADPH from the light-dependent reactions to produce high-energy sugars for long-term storage.
The Calvin cycle does NOT require light.

45. Thylakoids light CO2 H2O NADP+ ADP + P Calvin Cycle ATP NADPH Sugars
Chloroplast
Chloroplast
NADP+
ADP + P
Chloroplast
Thylakoids
Light-
Dependent
Reactions
Calvin
Cycle
ATP
NADPH

46. The Calvin Cycle: (4 Steps)
CO2 enters the cycle
Six carbon dioxide molecules enter and combine with six 5-Carbon molecules.
Result: 12 3-carbon molecules

47. The Calvin Cycle Energy input
The 12 3-carbon molecules are converted into high energy forms using ATP and NADPH
During this process, 12 ATP  12 ADP
During this process, 12 NADPH  12 NADP+

48. The Calvin Cycle
6-carbon sugar produced from two 3-carbon molecules removed to produce sugar
5-carbon molecules regenerated
10 remaining 3-carbon molecules converted into six 5-carbon molecules
This requires 6 ATP  6 ADP
These 5-carbon molecules can be reused in step A.

49. The Calvin Cycle CO2 Enters the Cycle Energy Input 5-Carbon Molecules
Regenerated
6-Carbon Sugar
Produced

50. Photosynthesis Light- dependent reactions Calvin cycle Thylakoid
includes
Light-
dependent
reactions
Calvin cycle
takes place in
uses
use
take place in
H2O and Energy from
sunlight
Thylakoid
membranes
NADPH
and ATP
Stroma
CO2
to produce of
to produce
High-energy
sugars
ATP
NADPH O2
Chloroplasts

51. Photosynthesis Light- dependent reactions Calvin cycle Thylakoid
includes of
take place in
takes place in
uses
to produce
use
Light-
dependent
reactions
Calvin cycle
Thylakoid
membranes
Stroma
NADPH
ATP
Energy from
sunlight O2
Chloroplasts
High-energy
sugars

52. Photosynthesis is important for almost all life on Earth because it —
A produces oxygen
B uses simple elements
C is responsible for most decay
D releases usable forms of nitrogen

53. A B What is this picture showing? chloroplast
What is letter A? __________
What is letter B? __________
chloroplast
stroma
thylakoid

54. Thylakoids CO2 H2O Light NADP+ ADP + P Calvin Cycle ATP NADPH Sugars
Chloroplast
Chloroplast
NADP+
ADP + P
Chloroplast
Thylakoids
Light-
Dependent
Reactions
Calvin
Cycle
ATP
NADPH O2

55. Light Dependent or Calvin Cycle?
Occurs in the stroma
Needs CO2
Produces ATP and NADPH
Occurs in the thylakoid membranes
Needs sunlight
Can occur in the dark
Uses ATP and NADPH
Produces a 6-Carbon Sugar
Calvin Cycle
Calvin Cycle
Light Dependent
Light Dependent
Light Dependent
Calvin Cycle
Calvin Cycle
Calvin Cycle