Unit 11, Lecture 4
›  Topic:
Energy in the Ecosystem
›  Cellular
Respiration
›  Carbon Dioxide and Climate Change
›  Covers
Information from:
›  Chapter
7
Review: Characteristics of Life
NOTE: This slide is for reviewing previous information. You should
include this information into your notes ONLY if you do not remember
the information.
All living organisms have the following characteristics:
1.  Made up of one or more cells
2.  Cells are highly organized and have different cellular
structures (organelles) for different functions
›  Remember: Form Fits Function!
3.  Reproduce – Essential to survival of the species, parent
passes on genes to offspring
4.  Evolve – a change in the species’ genes over many
generations. Changes may create a new phenotype.
Review: Characteristics of Life
NOTE: This slide is for reviewing previous information. You should
include this information into your notes ONLY if you do not remember
the information.
5. 
6. 
7. 
8. 
Maintain Homeostasis – stable internal conditions
Interdependence of Organisms – All species are
dependent on the other species in the ecosystem
Growth – all organisms grow and need energy
(food and nutrients) to grow
Energy – All organisms need and use energy
›  Autotroph (producer) – makes own food/
energy
›  Heterotroph (consumer) – consumes other
organisms to get food/energy
Energy
›  All
living organisms need a source of food and nutrients to
survive
›  When
organic compounds (food molecules) are broken
down, energy is released.
›  This energy is used for various purposes in the
organism, including generating body heat and
making ATP (cellular energy)
›  ATP is used to power many reactions inside the
organism
›  Nutrients
are used to create new cells, new organelles,
to repair damaged tissues, to grow hair/nails/etc.
Cellular Respiration
›  The
process of breaking down food to create ATP
is known as cellular respiration
›  During
cellular respiration, food energy is
converted into cellular energy.
›  Remember: During photosynthesis, plants
converted sun energy into cellular energy (ATP
and NADPH) and store the energy in the bonds
of organic compounds (food).
›  ALL
living organisms go through cellular
respiration, including plants!
Cellular Respiration
›  Cellular
respiration occurs in the “power house”
of the cell, the mitochondria.
›  Mitochondria are specialized organelles that
have a double membrane, their own DNA
and produce ATP
Cellular Respiration
›  Cellular
respiration is made up of 2 main parts
›  Part 1: Glycolysis
› Breaks down large organic molecules into a
smaller molecule known as Pyruvic Acid
› Pyruvic Acid – 3 carbon molecule, small
organic molecule
› Pyruvic Acid is small enough to diffuse into
the mitochondria
› This process produces some cellular energy
(ATP and NADH)
Cellular Respiration
›  Cellular
respiration is made up of 2 main parts
›  Part 2: Respiration
› Anaerobic – occurs when there is little to no
oxygen
› Also known as fermentation
› Not very efficient, does not produce any
more ATP
› Aerobic – occurs when mitochondria has a
large supply of oxygen, very efficient process
› Produces a lot of ATP
› This is the process humans mainly use
Part 2: Respiration
›  Anaerobic
Respiration – Occurs when little to no
oxygen is available to mitochondria, also known
as Fermentation
›  Lactic Acid Fermentation
› Happens in mammals and some types of
bacteria
› Converts 3-carbon pyruvic acid into 3-carbon
lactic acid
› Does not create any more ATP, but creates
material necessary for Glycolysis to happen
› Glycolysis does create some ATP
Part 2: Respiration
›  Anaerobic
Respiration
›  Alcohol Fermentation
› Used by some types of fungi and bacteria
› Converts 3-carbon pyruvic acid into a 2-carbon
ethyl alcohol and a molecule of carbon dioxide
› Does not create any more ATP, but creates
material necessary for Glycolysis to happen
› Glycolysis does create some ATP
Part 2: Respiration
›  Aerobic
Respiration – Occurs when oxygen is
available to mitochondria
›  Completely breaks down 3-carbon pyruvic acid
into three molecules of Carbon Dioxide (CO2)
› Energy is released each time a bond is broken
› This energy can be used to produce ATP
›  For every glucose molecule (C6H12O6) that is
broken down through aerobic respiration, it
generates a total of 38 ATP molecules!
› This is only 66% of the available energy in the
glucose molecule. The rest of the energy is lost
as heat (generates body heat)
Part 2: Respiration
›  Equation
› 
for Aerobic Respiration:
Glucose + Oxygen à Carbon Dioxide + Water + Energy
›  Chemical
Equation (yes, you have to know this!!!)
›  C6H12O6 + 6O2 à 6CO2 + 6 H2O + ATP
Is Carbon Dioxide Bad?
›  The
waste product of cellular respiration is carbon
dioxide.
›  The carbon dioxide is then released into the
atmosphere where it can be absorbed by plants to
use during photosynthesis.
›  Carbon Dioxide is one of the main Greenhouse Gases.
›  Greenhouse gas – traps some of sun’s heat, warms
Earth’s surface.
Is Carbon Dioxide Bad?
›  Greenhouse
gases are necessary for life to exist on
Earth! They are not all bad.
›  However,
the amount of greenhouse gases being
released into the atmosphere is much higher than
ever before. This means that more of the sun’s heat
is being trapped on Earth, leading to an increase in
Earth’s surface temperatures.
›  This used to be known as “Global Warming”, but it
is now known as “Climate Change” because
there are more changes occurring on Earth
besides temperature changes.
Does Cellular Respiration Cause Air Pollution?
›  No!
The amount of carbon dioxide released by
plants, animals, bacteria, fungi and protists during
cellular respiration is not at a harmful level to Earth.
›  However, there are other processes that occur on
Earth that are similar to cellular respiration and
release carbon dioxide.
›  Decomposition – in this process, tissues (made up
of organic compounds) are broken down.
Carbon dioxide is released.
Does Cellular Respiration Cause Air Pollution?
›  Burning
crops/wood/etc – in this process, the energy
stored in plants is released during the burning process.
Carbon dioxide and other (harmful) gases are released.
›  Burning
fossil fuels – Fossil fuels were formed by the
incomplete decomposition of plants and animals from
millions of years ago. These fuels (coal, gas, oil) are
made up of organic compounds! When they are
burned, it releases energy, carbon dioxide and other
(harmful) gases and particles.
›  These
two activities occur mostly because of human
activity have drastically increased the amount of
carbon dioxide in our atmosphere
End of Lecture 4