Energy and Energy Transfer
How the earth captures the sun’s energy and uses it to “do work”

What is energy?
– ability to do work
Cars need energy to move
Animals need energy to grow, move, make noise, etc

Types of energy
• Mechanical energy
– Move cilia, flagella, cytoskeleton, muscles
• Transport energy
– Active transport – pumping ions and molecules across a membrane against the gradient
• Chemical energy (like ATP)
– Stored in bonds. Can be used to start reactions that may not start spontaneously

Where do cars get energy?
– from burning fuel
–Specifically oil and gasoline

Chemical Energy is stored in fuels
- Burning oil and gasoline release energy in the form of heat and light ; The energy also allows the car to move.
- Gasoline is organic (C and H). When gasoline reacts with oxygen you get a combustion reaction. The products of
ALL combustion reactions are carbon dioxide (CO2) and Water (H20)

- Food!
What is our fuel?
- Specifically
Glucose
(simple carb)
- We disassemble glucose and put the energy from the bonds into ATP

Creating ATP

But where does the energy stored in glucose in our food come from?
THE SUN!!!

Really? How?
• Let go through step by step.
1. Where did your glucose come from?

2. How did the glucose get in the food?
3.How did she get the glucose?

4. How did the glucose get in the grass?
5. Where did the energy to make the glucose come from?

SO, long story short,
- the chloroplasts take energy from the sun and put it into a glucose molecule (Photosynthesis)
- through the food chain, glucose gets passed from organism to organism
- eventually mitochondria of some organism takes the energy back out, by breaking down the glucose (Cell respiration)

Types of Batteries
• Adenosine Triphosphate: ATP
– cycles between ATP (high energy) and ADP (low energy) by adding or removing a phosphate

Types of Batteries
• Electron Carriers: cycle between low energy “empty” form and high energy
“full” form by adding or removing electrons.
–We can “empty” these electron carriers to charge ATP

Types of Batteries
–There are three different electron carriers: NADPH; NADH and
FADH2

Let’s start by getting the energy from the sun into the glucose molecule

Key terms:
• Heterotrophs: Organisms that get food from somewhere else
–Examples??

• Autotrophs: organisms that make food for themselves
–Photoautotrophs use light energy to make their food
• Examples?
–Chemoautotrophs use the energy in inorganic compounds to make their food
• Examples?

• Understanding a little about light is important! Refer to your “Science of light and Color” assignment to help!

Electromagnetic Spectrum

Where does photosynthesis happen
• http://dendro.cnre.vt.edu/forestbiology/pho tosynthesis.swf
• Not all cells in a plant photosynthesize.
Let’s take a moment to identify WHERE we would find chloroplasts

Photoautotrophs undergo
Photosynthesis
• So what organelle is in their cells?

Thylakoid
Granum
(plural
Grana)
Stroma

What makes it Green?
• Pigment called Chlorophyll
(There are two chlorophylls)
• A pigment is a substance that absorbs light

What color light bounces off chlorophyll?
GREEN!!!

• Carotenes and xanthophylls*: other plant pigments (orange and yellow) that absorb different wavelengths of sunlight than the chlorophylls do.
• When can we see these??
* ZAN-tho-fills
FALL!!!

Overall SUMMARY Reaction
• Photosynthesis requires MANY reactions but we can summarize it with the following reaction
6CO
2
+ 6H
2
O  C
6
H
12
O
6
+ 6O
2
(Glucose)
What other molecules participate in the reaction?
Why is energy shown “not in the reaction”?

Getting CO2 and Water into the leaf
Stomata
(plural)
Root
Hairs

How does energy get into the leaf?
The peaks are wavelengths that are ABSORBED by the leaf.
What colors are absorbed?
Some light is transmitted
(passes through) as well.
What colors are reflected?
Absorbed?

What type of cells absorb light energy?
MESOPHYLL
CELLS contain chloroplasts

• Two Phases of Photosynthesis
Light reactions: need light;
uses light energy to “charge” two energy molecules: ATP and NADPH
- proteins needed for the reaction are embedded in the thylakoid membrane
- Uses: 6H
2
O produces: 6O
2

How does this work?
• http://www.stolaf.edu/people/giannini/flashanimat/metab olism/photosynthesis.swf
• What component of water travels along the membrane and is utilized to form
NADPH?
• What component of water travels back and forth THROUGH the membrane and is utilized to form ATP?
YOU NEED TO KNOW THE ANSWERS TO
THESE TWO QUESTIONS!

• Two Phases of Photosynthesis
Calvin cycle : doesn’t need light;
Uses the ATP and NADPH “charged” by the light reactions (carry energy) to link CO
2 together to build C
6
H
12
O
6
- Enzymes for the Calvin cycle are found in the stroma
Reactant: 6CO
2
Product: C
6
H
12
O
6

Putting it Together

The poetry of photosynthesis
• http://www.pbs.org/wgbh/nova/nature/phot osynthesis.html

What wavelengths of light are absorbed?
Which pigments?

Thylakoid membrane
Photosystems:groups of pigments
Light splits water (H+ and e-)
Proton gradient  ATP
NADP carries electrons
Water starts inside the thylakoids
ATP and
NADPH end up in stroma

Glucose will do one of two things:
1. Move to the mitochondria to be converted into ATP through Cell respiration
2. Go through dehydration synthesis to build a big starch chain and be stored for future use

Follow the Energy
• Where did the energy start?
• Where did it go next?
• Where is it at the end of photosynthesis?

Factors that affect Photosynthesis
• Light intensity (how bright/strong)
• CO2 levels
• Water
• Wavelength (color of light)
• Temperature: 0 – 35 degrees C
Why do each of these affect photosynthesis?

Why Mistletoe at Christmas?
• Druids (100 AD) thought that
Mistletoe could help cure diseases and protect people from witches. They even thought it could help people and animals have more babies.
So the Druids had a special ceremony that would happen in late December or early
January. Priests would cut mistletoe out of oak trees and then give the mistletoe to people to hang in their houses so that it would ward off evil spirits.

Why kissing?
• The Vikings! (800 BCE) had a lot of gods
(like the Greeks did). One of their gods --
Balder -- was killed with a poison made from mistletoe. His mother -- Frigga -- was able to bring him back to life after three days by reversing the effects of the poison. Once she did that, she kissed everyone who walked under mistletoe because she was so happy to get her son back.

EXCEPTIONS
• Some protists are heterotrophic and photosynthetic
• Some plants are heterotrophic and photosynthetic
• Some plants are parasitic and photosynthetic.

Exceptions to the Rules:
• Autotrophic Bacteria:
–Example: Cyanobacteria
(“Blue” bacteria)

Exceptions to the Rules:
• Autotrophic Protists:
–Example: Volvox and
Euglena

Exceptions to the Rules:
• Heterotrophic plants: some plants can get some food from other organisms
– EXAMPLE: Mistletoe: makes food
(PS) AND takes sap (high in sugar) from other trees
Hemi - parasite

Exceptions to the Rules:

Exceptions to the Rules:

How do we get the energy back out?
Cell Respiration – a series of chemical reactions that extract energy from glucose to “charge” ADP to make ATP.
Starts in the cytoplasm and ends in the mitochondria.

How do we get the energy back out?

Overall reaction
C
6
H
12
O
6
+ 6O
2
 6CO
2
+ 6H
2
O
ATP

Two types of Cellular Respiration
Anaerobic: no free oxygen required
- performed by most bacteria
- Also by yeast and animal cells when lacking O2
- two steps: Glycolysis, fermentation
- makes 2 ATP per glucose

Two types of Cellular Respiration
• Aerobic: requires FREE oxygen, O2 gas to get
ATP from glucose
– three steps: glycolysis, krebs, electron transport chain
– performed by plants, animals, yeast, protists, fungus.
– Generates 36 ATP per glucose

Anaerobic step 1: Glycolysis
• Occurs in cytoplasm
• Summary: split glucose in half to charge a few
ATP and NADH
• Reaction: Glucose  2 pyruvate
• Energy molecules used: 2ATP
• Energy molecules made: 4ATP and 2NADH

Fermentation
• Occurs in cytoplasm
• Summary: “empty” the NADH so we can repeat glycolysis with the next glucose
–2Pyruvate  CO2 and Ethanol (yeast) or
- 2Pyruvate  Lactic Acid (bacteria and muscle cells)
• NO MORE ATP CHARGED!

Anaerobic:
- Glycolysis: used 2, made 4
- Fermentation: used 0, made 0
Total: +2 per glucose

Aerobic step 1: Glycolysis
• SAME AS STEP 1 OF ANAEROBIC!

Krebs
• Occurs in mitochondria
• Summary: break down pyruvate into
CO2; use energy in pyruvate to charge ATP, NADH and FADH2

Krebs
Reaction:
–2Pyruvate  2Acetyl-CoA + 2CO
2
–2Acetyl-CoA  4CO
2
–Energy molecules made: 2ATP +
2FADH + 8NADH
–Can bacteria do Krebs??

Electron Transport Chain
• Occurs in mitochondria
• Summary: Gather up ALL the electron carriers and “empty” them to “charge” lots of ATP

Electron Transport Chain
• Reaction:
–O2  H2O
Energy molecules USED: 10 NADH (from krebs and glycolysis) + 2 FADH (from krebs)
Energy molecules MADE: 32 ATP

Aerobic:
- Glycolysis: used 2, made 4
- Krebs: used 0, made 2
- ETC: used 0, made 32
Total: +36 ATP per glucose

Overall Energy Summary for Aerobic Respiration
Reactants (used up/broken down) Products (created/built up)
Glucose + 2ATP  2 Pyruvate + 4ATP + 2NADH
2 Pyruvate  2CO2 + 2Acetyl-CoA + 2NADH
2Acetyl-CoA
10NADH + 2FADH2 + 6O2


What’s Left?

6NADH + 2FADH2 + 2ATP+ 4CO2
32ATP + 6CO2 + 6H2O
Final Reaction for Aerobic Respiration

Putting it together:
Sun
Chloroplast
CO2 + H2O
36ATP
Mitochondria
C
6
H
12
O
6
+ O2