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8–1 Energy and Life
A. Autotrophs and Heterotrophs
B. Chemical Energy and ATP
1. Storing Energy
2. Releasing Energy
C. Using Biochemical Energy
Section 8-1
Section Outline
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8-1A. Autotrophs and Heterotrophs
Autotrophs are organisms that are capable of making their own food, such as plants.Heterotrophs are organisms that cannot directly use the sun’s energy. Thus, they obtain energy from the foods they consume.
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8-1B. Chemical Energy and ATP
Energy can come in many forms, including light, heat, and electricity.
Living things use chemical energy. Adenosine triphosphate is one of the principal chemical compounds that cells use to store and release energy.
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Adenine Ribose 3 Phosphate groups
Section 8-1
ATP
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B-1 Storing Energy
ATP consists of adenine, a 5 carbon sugar called ribose, and three phosphate groups (key to storing and releasing energy).
ATP vs. ADP – adenosine diphosphate
ATP is like a fully charged battery.
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ADP ATP
Energy
EnergyAdenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)
Partiallychargedbattery
Fullychargedbattery
Section 8-1
Figure 8-3 Comparison of ADP and ATP to a Battery
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ADP ATP
Energy
EnergyAdenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)
Partiallychargedbattery
Fullychargedbattery
Section 8-1
Figure 8-3 Comparison of ADP and ATP to a Battery
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B2 – Releasing Energy
Energy is released from ATP when the chemical bonds break between the second and third phosphates.
ATP has enough energy to supply the needs of active transport, protein synthesis, and muscle contraction.
Basic energy source of all cells.
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C. – Using Biochemical Energy
Many cell membranes contain a sodium-potassium pump, which pumps ions into and out of the cell.
ATP provides the energy to maintain that type of active transport.
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Continued…
ATP powers the synthesis of proteins, nucleic acids, and responses to chemical signals at the cell surface.
Light from a firefly produced by ATP.
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Continued…
ATP is not abundant in the cell.It is great for transferring energy but not for storing large amounts of energy over long periods of time. Sugars, starches, etc. 90X more chemical energy.Cells can make ATP easily from ADP
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8–2 Photosynthesis: An Overview
A.Investigating Photosynthesis
1.Van Helmont’s Experiment
2.Priestley’s Experiment
3.Jan Ingenhousz
4.Conclusion
B.The Photosynthesis Equation
C. Light and Pigments
Section 8-2
Section Outline
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8-2 Photosynthesis Overview
Plants use the energy of sunlight to convert water and carbon dioxide into high-energy carbohydrates (sugars and starches) and oxygen (waste-product).
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A-1.Van Helmont’s Experiment
1.Measured the mass of a pot of dry soil and a seedling.
2.Watered the plant regularly. 3.End of five years, measured the small
tree to find that it gained about 75kg.4.The mass of the soil was basically
unchanged.
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Continued…
He concluded that most of the mass gain came from the water because it was the only thing added to the plant.
However, the water only accounted for the “hydrate” portion of “carbohydrate”.
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A-2. Priestley’s Experiment
1.Put candle under a jar..went out..why?
2.He repeated the experiment with a live sprig of mint in the jar as well. The candle would remain lit for a while.
3.It proved that the plant produced oxygen.
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A-3. Jan Ingenhousz
He showed that Priestley’s experiment only worked when the plant was exposed to light.
Proving the light was necessary for plants to produce oxygen.
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A-4. Overall Conclusion
In the presence of light, plants transform carbon dioxide and water into carbohydrates, and they also release oxygen.
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Light Energy
Chloroplast
CO2 + H2O Sugars + O2
Section 8-2
Photosynthesis: Reactants and Products
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8-2B The Photosynthesis Equation
6CO2 + 6H2O C6H12O6 + 6O2
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8-2C Light and Pigments
Photosynthesis requires light and chlorophyll, a molecule in chloroplasts.
Energy travels from the sun in the form of light. (wavelengths – visible spectrum)
Plant’s gather the sun’s energy with light absorbing molecules called pigments.
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Absorption of Light byChlorophyll a and Chlorophyll b
V B G YO R
Chlorophyll b
Chlorophyll a
Section 8-2
Figure 8-5 Chlorophyll Light Absorption
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Continued…
The principle pigment is chlorophyll. There two types, a and b.
Chlorophyll absorbs certain wavelengths of the visible spectrum very well.
It does not absorb the green portion very well, which is why plants look green. (Green light is being reflected.)
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Continued…
Because light is energy, any object that absorbs it, absorbs energy.
Chlorophyll molecules transfers its energy to electrons. Then these electrons make photosynthesis work.
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A Look Into the Future
It is 100 years in the future and you are a research scientist. An enormous volcanic eruption has recently sent huge quantities of dust and ash into the atmosphere.
Working with a partner, make a list of how this event will affect each of the following:
1. photosynthesis
2. plant life
3. animal life
4. human societies
Section 8-3
Interest Grabber
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8–3 The Reactions of Photosynthesis
A. Inside a Chloroplast
B. Electron Carriers
C. Light-Dependent Reactions
D. The Calvin Cycle
E. Factors Affecting Photosynthesis
Section 8-3
Section Outline
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8-3A. Inside a Chloroplast
Structure - double membrane
Thylakoids – sac-like photosynthetic membranes that contain the photosynthetic pigments
The photosynthetic pigments (including chlorophyll) are called photosystems.
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Continued….
Closed compartment with a central space
Granna (singular grannum) stacks of thylakoids
Stroma – gel-like matrix surrounding the thylakoids
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8-3B Electron Carriers
NADPHHigh energy electrons need a way to be
transported in the chloroplastsNADP – is one of these carrier molecules1.It accepts and holds 2 high energy
electrons along with a hydrogen ion2.NADP is then NADPH
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Continued…
The energy is then trapped in a compound that can carry these energy storing molecules throughout the cell
See figure 8.7 on page 209
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8-3C Light Dependent Reactions
They produce oxygen gas and convert ADP and NADP into the energy carriers ATP and NADPH.
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Continued… STEPS
1.Pigments in Photosystem II absorb light.
2.Energy from the light is absorbed by electrons, increasing their energy level.
3.The high energy electrons are passed to the electron transport chain.
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Continued…
4. New electrons are obtained in the thylakoid space by breaking water molecules into 2 electrons (which replaces the electrons the chlorophyll has released to the electron transport chain)
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Photosynthesis
includes
of
take place intakes place in uses
to produce to produce
use
Light-dependentreactions
Calvin cycle
Thylakoidmembranes Stroma NADPHATPEnergy from
sunlight
ATP NADPH O2 Chloroplasts High-energysugars
Section 8-3
Concept Map
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Chloroplast
Light
O2
Sugars
CO2
Light-Dependent Reactions
CalvinCycle
NADPH
ATP
ADP + PNADP+Chloroplast
Section 8-3
Figure 8-7 Photosynthesis: An Overview
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HydrogenIon Movement
Photosystem II
InnerThylakoidSpace
ThylakoidMembrane
Stroma
ATP synthase
Electron Transport Chain Photosystem I ATP Formation
Chloroplast
Section 8-3
Figure 8-10 Light-Dependent Reactions
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ChloropIast
CO2 Enters the Cycle
Energy Input
5-CarbonMoleculesRegenerated
Sugars and other compounds
6-Carbon SugarProduced
Section 8-3
Figure 8-11 Calvin Cycle
Videos
Click a hyperlink to choose a video.
ATP Formation
Photosynthesis
Light-Dependent Reactions, Part 1
Light-Dependent Reactions, Part 2
Calvin Cycle
Click the image to play the video segment.
Video 1
ATP Formation
Click the image to play the video segment.
Video 2
Photosynthesis
Click the image to play the video segment.
Video 3
Light-Dependent Reactions, Part 1
Click the image to play the video segment.
Video 4
Light-Dependent Reactions, Part 2
Click the image to play the video segment.
Video 5
Calvin Cycle
ATP activity
Interactive test
For links on Calvin cycle, go to www.SciLinks.org and enter the Web Code as follows: cbn-3082.
For links on photosynthesis, go to www.SciLinks.org and enter the Web Code as follows: cbn-3083.
Go Online
Interest Grabber Answers
1. What are the benefits of having a bank account?
To save money and earn interest.
2. What do you have to do if you need some of this money?
Go to the bank and take out the money you need.
3. What might your body do when it has more energy than it needs to carry out its activities?
Students will likely say that the body stores the energy.
4. What does your body do when it needs energy?
Student answers may include that energy is gotten from food.
Interest Grabber Answers
1. A solar-powered calculator uses solar cells that are found in rows along the top of the calculator. Into what kind of energy is the light energy converted so that the calculator works?
They convert light energy into electrical energy.
2. Recall that plants use light energy from the sun to make food. Into what kind of energy is the light energy converted by plants?
Plants convert light energy into chemical energy.
3. Most plants, no matter what size or shape they are, have some parts that are green. Which parts of a plant are usually green?
Leaves are green, as are some stems.
4. What does the green color have to do with the plant’s ability to convert light energy into the energy found in the food it makes?
The green color is the pigment chlorophyll, which absorbs light energy from the sun and converts it to chemical energy in the process of photosynthesis.
Interest Grabber Answers
Working with a partner, make a list of how this event will affect each of the following:
1. photosynthesis The rate of photosynthesis will decrease due to reduced sunlight.
2. plant life Plants will grow more slowly or die off due to decreased rate of photosynthesis.
3. animal life Animal populations will decrease after a while due to fewer plants for herbivores to eat. Fewer herbivores will eventually result in fewer carnivores. Also, less oxygen will be available.
4. human societies Human societies will have to adjust their eating habits as some food species die out.
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