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Some Announcements
Monday October 6
UW Evening Degree Program Information Table
4-6:00 pm, Hallway, 1st floor, College Center
Biology and Society: Feeling
the Burn
Tuesday, October 7
Eastern WA@ BCC Information Table
10am-1:00pm, Hallway, 1st floor, College Center
Wednesday, October 8
Washington State University Advising Appointments
– When you exercise,
• Muscles need energy in order to perform work.
• Your cells use oxygen to release energy from
the sugar glucose.
Appointments are still available! Students interested in WSU should be sure to call 527-3658
or drop by Advising to make an appointment.
Wednesday, October 8
Choosing a Major Workshop
Students who are beginning the process of exploring major options…be sure to join Judy Gage
and Jenny Mao for this interactive workshop.
1-2:00pm, Club Room
– Aerobic metabolism
• Occurs when enough oxygen reaches cells to support
energy needs.
– Anaerobic metabolism
• Occurs when the demand for oxygen outstrips the
body’s ability to deliver it.
– Aerobic metabolism
• Occurs when enough oxygen reaches cells to support
energy needs.
– Aerobic metabolism
• Occurs when enough oxygen reaches cells to support
energy needs.
– Anaerobic metabolism
• Occurs when the demand for oxygen outstrips the
body’s ability to deliver it.
– Anaerobic metabolism
• Without enough oxygen, muscle cells break down
glucose to produce lactic acid.
– Anaerobic metabolism
• Occurs when the demand for oxygen outstrips the
body’s ability to deliver it.
• Lactic acid is associated with the “burn” associated
with heavy exercise.
• If too much lactic acid builds up, your muscles give
out.
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Energy Flow and Chemical Cycling
in the Biosphere
– Physical conditioning
allows your body to
adapt to increased
activity.
Inflow
of
light
energy
• The body can increase its
ability to deliver oxygen
to muscles.
Loss
of
heat
energy
Chemical
energy
(food)
– Long-distance runners
wait until the final sprint
to exceed their aerobic
capacity.
Producers
Cycling
of
nutrients
(plants and
other
photosynthetic
organisms)
– Fuel molecules in food
represent solar energy.
• Energy stored in food can
be traced back to the sun.
– Animals depend on
plants to convert solar
energy to chemical
Consumers energy.
(such as
animals)
• This chemical energy is in
the form of sugars and
other organic molecules.
Decomposers
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings
Producers and Consumers
Inflow
of
light
energy
Loss
of
heat
energy
Chemical
energy
(food)
Producers
Cycling
of
nutrients
(plants and
other
photosynthetic
organisms)
Consumers
(such as
animals)
Decomposers
– Photosynthesis
• Uses light energy
from the sun to
power a chemical
process that
makes organic
molecules.
• Occurs in the
leaves of
terrestrial plants.
– Producers
Inflow
of
light
energy
Loss
of
heat
energy
Chemical
energy
(food)
Producers
(plants and
other
photosynthetic
organisms)
Cycling
of
nutrients
• Biologists refer to
plants and other
autotrophs as the
producers in an
ecosystem.
– Consumers
Consumers
(such as
animals)
Decomposers
• Heterotrophs are
consumers,
because they eat
plants or other
animals.
– Autotrophs
Inflow
of
light
energy
• Are “self-feeders.”
• Include plants and
other organisms that
make all their own
organic matter from
inorganic nutrients.
Loss
of
heat
energy
Chemical
energy
(food)
Producers
(plants and
other
photosynthetic
organisms)
Cycling
of
nutrients
– Heterotrophs
Consumers
(such as
animals)
Decomposers
• Are “other-feeders.”
• Include humans and
other animals that
cannot make organic
molecules from
inorganic ones.
Chemical Cycling between Photosynthesis and
Cellular Respiration
– The ingredients for
photosynthesis are
carbon dioxide and water.
• CO2 is obtained from the
air by a plant’s leaves.
• H2O is obtained from the
damp soil by a plant’s
roots.
– Chloroplasts rearrange
the atoms of these
ingredients to produce
sugars (glucose) and
other organic molecules.
• Oxygen gas is a by-product
of photosynthesis.
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– Both plants and
animals perform
cellular respiration.
Combustion
• Cellular respiration is a
chemical process that
harvests energy from
organic molecules.
• Cellular respiration
occurs in mitochondria.
– The waste products of
cellular respiration,
CO2 and H2 O, are used
in photosynthesis.
Cellular Respiration
Cellular Respiration: Aerobic Harvest
of Food Energy
– Cellular respiration
• Is the main way that chemical energy is
harvested from food and converted to ATP.
• Is an aerobic process—it requires oxygen.
Copyright © 2007 Pearson Education Inc., publishing as Pearson Benjamin Cummings
The Relationship between Cellular Respiration and
Breathing
– Cellular respiration
and breathing are
closely related.
• Cellular respiration
requires a cell to
exchange gases
with its
surroundings.
• Breathing
exchanges these
gases between the
blood and outside
air.
The Overall Equation for Cellular Respiration
– A common fuel molecule for cellular
respiration is glucose.
• The overall equation for what happens to
glucose during cellular respiration
Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
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The Role of Oxygen in
Cellular Respiration
Redox Reactions
– Chemical reactions that transfer electrons from
one substance to another are called
oxidation-reduction (redox) reactions.
– During cellular respiration, hydrogen and
its bonding electrons change partners.
– The loss of
electrons during a
redox reaction is
called oxidation.
• Hydrogen and its electrons go from sugar to
oxygen, forming water.
Image from Purves et al., Life: The Science of Biology, 4th
Edition, by Sinauer Associates (www.sinauer.com) and
WH Freeman (www.whfreeman.com)
Redox Reactions
– Chemical reactions that transfer electrons from
one substance to another are called
oxidation-reduction (redox) reactions.
– The acceptance of
electrons during a
redox reaction is
called reduction.
Redox Reactions
a transfer of electrons
– The loss of
electrons during a
redox reaction is
called oxidation.
Image from Purves et al., Life: The Science of Biology, 4th
Edition, by Sinauer Associates (www.sinauer.com) and
WH Freeman (www.whfreeman.com)
– The acceptance of
electrons during a
redox reaction is
called reduction.
– Why does electron transfer to oxygen release
energy?
• When electrons move from glucose to oxygen, it is as
though they were falling, thus, releasing their
potential energy.
NADH and Electron Transport Chains
– The path that electrons take on their way
down from glucose to oxygen involves
many steps.
• This “fall” of electrons releases energy during cellular
respiration.
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– The first step is an
electron acceptor called
NAD+ .
• The transfer of electrons
from organic fuel to NAD+
reduces it to NADH.
– The rest of the path
consists of an electron
transport chain.
• This chain involves a series
of redox reactions.
• These lead ultimately to the
production of large amounts
of ATP.
Stage 1: Glycolysis
– A molecule of glucose is split into two
molecules of pyruvic acid.
– Glycolysis makes some ATP directly when
enzymes transfer phosphate groups from
fuel molecules to ADP.
The Metabolic Pathway of Cellular Respiration
– Cellular respiration is an
example of a metabolic
pathway,
• A series of chemical
reactions in cells.
– All of the reactions
involved in cellular
respiration can be
grouped into three main
stages:
• Glycolysis
• The citric acid cycle
• Electron transport
– Glycolysis breaks a six-carbon glucose into
two three-carbon molecules.
• These molecules then donate high energy
electrons to NAD+ , forming NADH.
Stage 2: The Citric Acid Cycle
– The citric acid cycle completes the
breakdown of sugar.
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– In the citric acid cycle, pyruvic acid from
glycolysis is first “prepped” into a usable
form, Acetyl CoA.
– In the citric acid cycle, pyruvic acid from
glycolysis is first “prepped” into a usable
form, Acetyl CoA.
– The citric acid cycle extracts the energy of sugar
by breaking the acetic acid molecules all the way
down to CO2 .
Stage 3: Electron Transport
– Electron transport releases the energy your
cells need to make most of their ATP.
•The cycle uses
some of this
energy to make
ATP.
•The cycle also
forms NADH
and FADH2.
– The molecules of electron transport chains are
built into the inner membranes of mitochondria.
• The chain functions as a chemical machine that uses
energy released by the “fall” of electrons to pump
hydrogen ions across the inner mitochondrial
membrane.
• These ions store potential energy.
– When the hydrogen ions flow back through
the membrane, they release energy.
• The ions flow through ATP synthase.
• ATP synthase takes the energy from this flow,
and synthesizes ATP.
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– The first step is an electron
acceptor called NAD+.
• The transfer of electrons from
organic fuel to NAD+ reduces it
to NADH.
The Versatility of Cellular Respiration
– Cellular respiration can “burn” other kinds
of molecules besides glucose:
– The rest of the path consists of
an electron transport chain.
• This chain involves a series of
redox reactions.
• These lead ultimately to the
production of large amounts of
ATP.
Adding Up the ATP from Cellular Respiration
Fermentation: Anaerobic
Harvest of Food Energy
– Some of your cells can actually work for
short periods without oxygen.
– Fermentation
• Is the anaerobic harvest of food energy.
Fermentation in Human
Muscle Cells
– Glycolysis breaks a six-carbon glucose into
two three-carbon molecules.
• These molecules then donate high energy
electrons to NAD+ , forming NADH.
– After functioning anaerobically for about 15
seconds,
• Muscle cells will begin to generate ATP by the
process of fermentation.
– Fermentation relies on glycolysis to
produce ATP.
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– Glycolysis is the metabolic pathway that
provides ATP during fermentation.
• Pyruvic acid is reduced by NADH, producing NAD+ ,
which keeps glycolysis going.
• In human muscle cells, lactic acid is a by-product.
– The food industry uses yeast to produce
various food products.
Fermentation in Microorganisms
– Various types of microorganisms perform
fermentation.
• Yeast cells carry out a slightly different type of
fermentation pathway.
• This pathway produces CO2 and ethyl alcohol.
Evolution Connection:
Life on an Anaerobic Earth
– Ancient bacteria probably used glycolysis to
make ATP long before oxygen was present in
Earth’s atmosphere.
• Glycolysis is a metabolic heirloom from the earliest
cells that continues to function today in the harvest of
food energy.
Copyright © 2007 Pearson Education, Inc. publishing as Pearson Benjamin Cummings
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