Transcript Section 8-1

Section Outline
Section 8-1
8–1 Energy and Life
A.
Autotrophs and Heterotrophs
B.
Chemical Energy and ATP
1. Storing Energy
2. Releasing Energy
C.
Using Biochemical Energy
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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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ATP
Section 8-1
Adenine
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Ribose
3 Phosphate groups
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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Figure 8-3 Comparison of ADP and
ATP to a Battery
Section 8-1
ADP
ATP
Energy
Adenosine diphosphate (ADP) + Phosphate
Partially
charged
battery
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Energy
Adenosine triphosphate (ATP)
Fully
charged
battery
Figure 8-3 Comparison of ADP and
ATP to a Battery
Section 8-1
ADP
ATP
Energy
Adenosine diphosphate (ADP) + Phosphate
Partially
charged
battery
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Energy
Adenosine triphosphate (ATP)
Fully
charged
battery
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 sodiumpotassium 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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Section Outline
Section 8-2
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
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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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Photosynthesis: Reactants and Products
Section 8-2
Light Energy
Chloroplast
CO2 + H2O
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Sugars + O2
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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Figure 8-5 Chlorophyll Light Absorption
Section 8-2
Absorption of Light by
Chlorophyll a and Chlorophyll b
Chlorophyll b
Chlorophyll a
V
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B
G
YO
R
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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Interest Grabber
Section 8-3
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
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Section Outline
Section 8-3
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
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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
NADPH
High energy electrons need a way to be
transported in the chloroplasts
NADP – is one of these carrier molecules
1.It accepts and holds 2 high energy
electrons along with a hydrogen ion
2.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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Concept Map
Section 8-3
Photosynthesis
includes
Lightdependent
reactions
Calvin cycle
use
take place in
Energy from
sunlight
Thylakoid
membranes
to produce
ATP
NADPH
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O2
takes place in
Stroma
uses
ATP
NADPH
of
to produce
Chloroplasts
High-energy
sugars
Figure 8-7 Photosynthesis: An Overview
Section 8-3
Light
CO2
Chloroplast
Chloroplast
NADP+
ADP + P
LightDependent
Reactions
Calvin
Cycle
ATP
NADPH
O2
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Sugars
Figure 8-10 Light-Dependent Reactions
Section 8-3
Photosystem II
Hydrogen
Ion Movement
Chloroplast
ATP synthase
Inner
Thylakoid
Space
Thylakoid
Membrane
Stroma
Electron
Transport Chain
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Photosystem I
ATP Formation
Figure 8-11 Calvin Cycle
Section 8-3
CO2 Enters the Cycle
Energy Input
ChloropIast
5-Carbon
Molecules
Regenerated
6-Carbon Sugar
Produced
Sugars and other compounds
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Videos
Click a hyperlink to choose a video.
ATP Formation
Photosynthesis
Light-Dependent Reactions, Part 1
Light-Dependent Reactions, Part 2
Calvin Cycle
Video 1
ATP Formation
Click the image to play the video segment.
Video 2
Photosynthesis
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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
Click the image to play the video segment.
Go Online
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.
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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