Transcript Cellular Respiration

Georgia Performance Standards:
SB3a. Explain the cycling of energy through the processes of
photosynthesis and respiration.
Essential Questions:
-How do plants and animals get energy?
-How is energy transferred from sunlight to glucose to ATP?
- How is energy stored and released from food molecules?
- How are the processes of photosynthesis and cellular respiration related?
Hook
Suppose you earned extra money by having a
part-time job. At first, you might be tempted to
spend all of the money, but then you decide to
open a bank account.
1. What are the benefits of having a bank account?
2. What do you have to do if you need some of this
money?
3. What might your body do when it has more
energy than it needs to carry out its activities?
4. What does your body do when it needs energy?
Warm-up: Autotroph &
Heterotroph Review
• Autotrophs:
– Use light energy from the sun to produce their
own food. (photosynthesis)
• Heterotrophs:
– Gain energy by consuming other source
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Metabolism
 All of the chemical reactions in a cell
 Photosynthesis—light energy from the Sun
is converted to chemical energy for use by
the cell
 Cellular respiration—organic molecules are
broken down to release energy for use by
the cell
8.1: Energy & Life
• ATP, made in the mitochondria of the
cell, is the basic energy source of all cells.
ATP = ENERGY
• It stores and releases energy
ATP =
Adenine
Ribose
Adenosine Triphosphate
3 Phosphate groups
Comparison of ADP and ATP to a Battery
ADP
ATP
Energy
Adenosine diphosphate (ADP) + Phosphate
Partially
charged
battery
Energy
Adenosine triphosphate (ATP)
Fully
charged
battery
See video clip
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
ATP: The Unit of Cellular Energy
 ATP releases energy
when the bond between
the second and third
phosphate groups is
broken, forming a
molecule called
adenosine diphosphate
(ADP) and a free
phosphate group.
ATP
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Transformation of Energy
 Energy is the ability to do work.
 Thermodynamics is the study of the flow
and transformation of energy in the
universe.
Chapter 8
Cellular Energy
8.1 How Organisms Obtain Energy
Laws of Thermodynamics
 First law—energy can be converted from
one form to another, but it cannot be created
nor destroyed.
 Second law—energy cannot be converted
without the loss of usable energy.
Formative Assessment:
1.What is the ultimate source of energy for plants?
2. What is ATP and what is its role in the cell?
3. Describe cellular activities that use the energy released by ATP.
4. How do autotrophs obtain energy? How do heterotrophs obtain
energy?
5. With respect to energy, how are ATP and glucose similar?
Ticket Out the Door
• Pg. 221 # 1-4
Warm-up: Trapping Energy
• Have you ever used a solar-powered
calculator?
• No matter where you go, as long as you
have a light source, the calculator works.
You never have to put batteries in it.
Warm-up: Trapping Energy
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?
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?
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?
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?
Chapter 8
Cellular Energy
8.2 Photosynthesis
Overview of Photosynthesis
 Photosynthesis occurs in two phases.
 Light-dependent reactions
 Light-independent reactions
8.2 Photosynthesis: From solar energy to
chemical energy
• Photosynthesis uses the energy of sunlight to convert
water and carbon dioxide into oxygen and high-energy
sugars (glucose)
6CO2 + 6H2O  C6H12O6 + 6O2
• Photosynthesis requires sunlight
• Reactants = water (H2O) and carbon dioxide (CO2)
• Products = glucose (C6H12O6) and oxygen (O2)
Photosynthesis: Reactants and Products
Light Energy
Chloroplast
CO2 + H2O
Sugars + O2
Photosynthesis is a series of reactions that uses energy from the sun to
convert water and carbon dioxide into sugars and oxygen.
Go toPhotosynthesis takes place in a plant organelle called the chloroplast.
Section:
What does a chloroplast look like?
The Chloroplast Dissected
• Chlorophyll pigments on the thylakoid
membrane in the chloroplasts of plants
absorb the energy in sunlight.
• That energy is transferred directly to
electrons in the chlorophyll molecules,
which causes photosynthesis to work.
– Chlorophyll A
– Chlorophyll B
Classification of Electromagnetic
Radiation
Copyright © Houghton
Mifflin Company. All
7–21
Light & Chlorophyll Pigments:
• Photosynthesis Also Requires Light and Chlorophyll
Pigments
• Sunlight is seen as white light (a mixture of
different wavelengths of light)
– Wavelengths of visible light are seen as certain colors
• Review Spectrum of visible Light
• Plants appear green because that is the color that
is reflected.
• The other colors of light are being absorbed.
Chlorophyll Light Absorption
Absorption of Light by
Chlorophyll a and Chlorophyll b
Chlorophyll b
Chlorophyll a
V
B
G
YO
R
Photosynthesis requires light and chlorophyll, which absorbs light energy. In the
graph, notice how chlorophyll a absorbs light in the violet and red regions of the
visible spectrum, while chlorophyll b absorbs light in the blue and red regions of the
visible spectrum.
Formative Assessment:
1. Describe the process of photosynthesis,
including the reactants and products.
2. Why are light and chlorophyll needed for
photosynthesis?
3. Why are plants green?
4. How well would a plant grow under pure yellow
light? Explain your answer.
Warm-up: 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
The Reactions of Photosynthesis
• Photosynthesis occurs in 2 stages.
– Light dependent Reaction
– Light –Independent Reaction (Dark Reaction)
First Stage of Photosynthesis
• Light-dependent Reactions = occurs in
the thylakoid membranes of chloroplast.
– Produces oxygen gas
– ADP ATP
– NADP+  NADPH (electron carrier molecule)
• Play video clip Part 2
Light-Dependent Reactions
Section
8-3
Photosystem II
Hydrogen
Ion Movement
Chloroplast
ATP synthase
Inner
Thylakoid
Space
Thylakoid
Membrane
Stroma
Electron
Photosystem I ATP Formation
Transport Chain
Chapter 8
Cellular Energy
Light-independent Reactions (Calvin Cycle
or Dark Reaction)
•
Occurs in the stroma
–
When sunlight excites electrons in chlorophyll, the electrons
gain energy.
–
The electrons are carried by a certain electron-carrying
molecule called NADP+
–
NADP+ accepts and holds 2 excited electrons along with
Hydrogen (H+). NADP+ is then converted into NADPH
•
•
–
NADP+ = oxidized form
NADPH = Reduced form
NADPH carries excited electrons from the light-dependent
reactions and uses them to produce high-energy sugars like
glucose.
Play Video Clip
Light Independent Reaction Calvin Cycle
CO2 Enters the Cycle
Energy Input
ChloropIast
5-Carbon
Molecules
Regenerated
6-Carbon Sugar
Produced
Sugars and other compounds
Chapter 8
Cellular Energy
Photosynthesis: An Overview
Section 8-3
Light
CO2
Chloroplast
Chloroplast
NADP+
ADP + P
LightDependent
Reactions
Calvin
Cycle
ATP
NADPH
O2
Sugars
Concept Map
Section 8-3
Photosynthesis
includes
Lightdependent
reactions
Calvin cycle
use
take place in
Energy from
sunlight
Thylakoid
membranes
to produce
ATP
Go to
Section:
NADPH
O2
takes place in
Stroma
uses
ATP
NADPH
of
to produce
Chloroplasts
High-energy
sugars
Factors Affecting the Rate of Photosynthesis:
• Shortage of water: slows or stops photosynthesis
– Name some plant adaptations that can reduces water
loss
• Temperature: to far above or below the temp. range can
damage the enzymes that help photosynthesis to
function.
– At very low temps. - slow or stop photosynthesis
– At very high temps. - slow or stop photosynthesis
• Amount of light:
– Increase light = increase photosynthesis
– Decrease light = decrease photosynthesis
See Interpreting Graphs
Pop Quiz:
1.
Summarize the light-dependent reactions.
2.
What reactions make up the Calvin cycle?
3.
What is the function of NADPH?
4.
How is light energy converted into chemical energy during
photosynthesis?
5.
Can the complete process of photosynthesis take place in
the dark? Explain your answer.
6.
Oxygen is made during which reaction of photosynthesis
(light dependent or light independent)?
7.
Glucose is made during which reaction of photosynthesis
(light dependent or light independent)?
Ticket Out The Door
• See handout for options
• Homework:
– Graphic Organizer Due Thursday
– Chapter 8 Guided reading Due Friday
Cellular Respiration
Warm-up:
• Do you like to run, bike, or swim? These
all are good ways to exercise. When
you exercise, your body uses oxygen to
get energy from glucose,
a six-carbon sugar.
Go to
Section:
Warm-up:
1. How does your body feel at the start of
exercise, such as a long, slow run? How do
you feel 1 minute into the run; 10 minutes into
the run?
2. What do you think is happening in your cells to
cause the changes in how you feel?
3. Think about running as fast as you can for 100
meters. Could you keep up this pace for a
much longer distance? Explain your answer.
Mitochondrion Structure
Living things get the energy they
need from food.
Both plant and animal cells carry
out the final stages of cellular
respiration in the mitochondria.
Chemical Energy and Food
• How much energy is actually present in food?
– One gram of the sugar glucose when burned in the
presence of oxygen, releases 3811 calories of heat
energy.
– A calorie is the amount of energy needed to raise the
temperature of 1 gram of water 1 Celsius degree.
– The Calorie (capital “C”) that is used on food labels is a
kilocalorie, or 1000 calories.
– Cells, of course, don’t “burn” glucose. Instead, they
gradually release the energy from glucose and other food
compounds.
Cellular Respiration
• What is cellular respiration?
– The catabolic pathway in which organic
molecules are broken down to release energy
for the cell to do work.
• (cell division, membrane transport, movement, repair,
etc….)
• Who does cellular respiration?
All living organisms
Chemical Reactions
• Cellular Respiration:
6O2 + C6H12O6+ ADP + Pi 6CO2 + 6H2O + ATP
(reactants)
(products)
• Photosynthesis:
6CO2 + 6H2O + ATP 6O2 + C6H12O6 + ADP + Pi
• The reactants of one process are the
products of the other
How does cellular respiration take place?
• 3 stages
– Glycolysis
– Krebs Cycle
– Electron Transport Chain
First Stage: Glycolysis
•
Glycolysis takes place in the cytoplasm
– Glucose (a 6 Carbon molecule) is broken in
half
– 2 molecules of pyruvic acid (a three carbon
chain) are formed
Glycolysis
Glucose
2 Pyruvic acid
To the electron
transport chain
Glycolysis
– During this process 2 ATP are used to activate the process of
glycolysis
– 4 ATP molecules are made. A net gain of 2 ATP are
produced. (-2 +4)=2
– 2 NAD+ molecules gain an electron in the form of hydrogen (H)
to produce 2 NADH molecules.
– 2 pyruvic acid molecules are also made
– Overall Chemical Equation for Glycolysis:
C6H12O6 + 2 NAD+ + 2 ADP  2Pyruvic Acid+ 2NADH + 2ATP
Oxygen or No Oxygen
What happens after glycolysis depends on whether there is
oxygen present in the cell or not
Glycolysis
Krebs Cycle
Fermentation
Anaerobic= No oxygen
Aerobic= Oxygen
needed
Alcohol
Fermentation
Lactic Acid
Fermentation
Electron Transport
Chain
Produces
2 ATP
Produces
2 ATP
Produces
36 ATP
Fermentation:
•
Releases energy in food molecules in the
absence of oxygen.
– Anaerobic = does not require oxygen
–
Regenerates NAD+ so glycolysis can
continue to produce ATP
Two Types of Fermentation:
• Alcohol Fermentation:
– Occurs in yeast & a few other microorganism
– Important part of bread baking
– Pyruvic acid + NADH  ethyl alcohol + CO2 + NAD+
• Lactic Acid Fermentation:
– Occurs in animals
– Pyruvic acid + NADH  lactic acid + NAD+
– Lactic Acid build up in your muscle cells during
exercise causes sore
What Keeps Glycolysis Going?
• Without NAD+, the cell cannot keep
Glycolysis going, and ATP production
would stop.
• Therefore NAD+ needs to be replenished.
• Lactic Acid Fermentation takes place to
replenish NAD+ so that Glycolysis can
continue to make ATP for the cell
Lactic Acid Fermentation
Section 9-1
Glucose
Go to
Section:
Pyruvic acid
Lactic acid
Cellular Respiration Pop Quiz:
1.
2.
3.
4.
5.
Describe the process of cellular respiration.
What are the 3 products of glycolysis?
Name the two main types of fermentation.
What is a calorie? A Calorie?
How is the function of NAD+ similar to that of
NADP+?
6. How are lactic acid fermentation and alcoholic
fermentation similar? How are they different?
Cellular Respiration: Occurs in all living organisms
• 3 stages to cellular respiration
1. Glycolysis = occurs in the cytoplasm
• One 6 carbon glucose is split into two 3-carbon
molecules called pyruvic acid
• Anaerobic conditions = Alcohol or Lactic Acid
Fermentation
• Aerobic conditions = Kreb’s Cycle
2. Kreb’s Cycle
3. Electron Transport Chain
Cellular Respiration
Glucose
(C6H1206)
+
Oxygen
(02)
Glycolysis
Krebs
Cycle
Electron
Transport
Chain
Carbon
Dioxide
(CO2)
+
Water
(H2O)
Kreb’s Cycle:
• In the presence of
oxygen, pyruvic acid
is broken down into
carbon dioxide.
• Occurs in
Mitochondrial Matrix
• See Video Clip
Kreb’s Cycle:
• 2 Pyruvic acid can be converted, in the presence of oxygen, into 2
acetyl-CoA, and carbon dioxide is given off.
• Acetyl-CoA is then converted into Citric Acid (First compound
formed during this cycle, hence the alternated name “Citric Acid
Cycle”
• Citric Acid (6 carbon) is broken down into a five-carbon molecule
and then a 4-carbon molecule. More carbon molecules are released
and ATP is produced.
• Reduced electron carrying molecules are also produced (4 NADH
and 1 FADH2).
Chapter 8
Cellular Energy
8.3 Cellular Respiration
 The net yield from
the Krebs cycle is:
 six CO2 molecules
 two ATP
 eight NADH
 two FADH2.
Electron Carrying Molecules
• Reduced electron carrying molecules are also
produced (4 NADH and 1 FADH2).
•
•
•
•
NAD+ = oxidized form
NADH = reduced form
FADH = oxidized form
FADH2 = reduced form
• NADH and FADH2 are moved to the electron
transport chain to generate the bulk of ATP
that the cell will use to do work.
Electron Transport Chain:
• In eukaryotes = occurs in inner membrane of
the mitochondrion
• In prokaryotes = occurs in the cell membrane
(Why? No membrane bound organelles)
• The electron transport chain uses the highenergy electrons from the Krebs cycle to
convert ADP into ATP.
• See Video Clips (2)
Electron Transport Chain
Electron Transport
Hydrogen Ion Movement
Channel
Mitochondrion
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production
Electron Transport Chain:
• A = Electrons are transported down the membrane
proteins
• B = Hydrogen ions (H+) build up in the inner membrane
space making it positively charge and the other side
negatively charged.
• C = The charge difference (review voltage- potential
channels) causes a protein called ATP Synthase to
rotate. Each time ATP Synthase rotates, a Phosphate
group (PO4-3) is added to ADP to form ATP.
• The electrons that were transported down the membrane
proteins combine with hydrogen ions, which are
accepted by oxygen to form water.
So why do we need oxygen during the
Kreb’s Cycle and the ECT?
• Oxygen is the final electron acceptor of
the electron transport chain to make
water.
• Oxygen is essential for getting rid of
low-energy electrons and hydrogen
ions, which are the wastes of cellular
respiration.
The total
Energy From
Glycolysis,
the Kreb’s
Cycle and the
Electron
Transport is
36 APT
How efficient is the process of
cellular respiration?
• The 36 ATP molecules the cell makes per one
glucose represents about 38 percent of the
total energy of glucose.
• What happens to the remaining 62 percent?
– It is released as heat, which is one of the reasons
your body feels warmer after vigorous exercise, and
you do not freeze in winter
– Remember energy pyramids….
Checkpoint Questions:
1. What happens to pyruvic acid during the Krebs cycle?
2.
How does the electron transport chain use the highenergy electrons from the Krebs cycle?
3. Why is cellular respiration considered to be much more
efficient than glycolysis alone?
4. How many molecules of ATP are produced in the entire
breakdown of glucose?
5. Compare photosynthesis and cellular respiration. How
are they similar? How are they different?