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					Cell Energy
A. Van der Fluit
South Gate High School
2006
Lecture Outline
The purpose of this lecture is to answer three
questions:
• Why should I care about cell energy?
• What is energy, anyway?
• How do cells get energy?
Why should I care about cell energy?
  1st - Cells need energy to do their jobs. Without
  energy, you wouldn’t be able to live!
    - growth and development
    -reproduction
    -movement
    -active transport of materials
  2nd - The need for energy is
  what connects you to
  other living things.
  So take care of these living
  things – without them
  you would die!
Consider this…
Just sitting in your chair right now, you are
burning about 81 calories per hour. (A calorie is
a unit used to measure energy). Think about the
last 24 hours, and explain to your neighbor where
you got the energy to do this from.
What is energy?
Energy is what allows things to be moved or
changed.
  - kicking a ball makes it move
  - cooking an egg makes it change color

Energy comes in many forms:
    -mechanical (gears turning in a car)
    -chemical (chemical bonds breaking)
    -light (ultraviolet radiation burning your skin)
    -sound (the music you listen to)
    -thermal (heating up food)
    -electrical (powering light bulbs, iPods, etc)
A Few More Things About Energy
• Energy can be stored, waiting to be used…
  –   A rock at the top of a hill
  –   A battery waiting to be used
  –   A piece of wood waiting to be burned
  –   Food waiting to be broken into smaller parts

                                             “POTENTIAL” energy

• Energy can be in use, causing motion or change…
  –   A rock rolling down the hill
  –   A battery powering an iPod
  –   A piece of wood burning
  –   Food being broken down, releasing energy


                                                 “KINETIC” energy
Self-Check: Kinetic or Potential?




            KINETIC
Self-Check: Kinetic or Potential?




         POTENTIAL
Self-Check: Kinetic or Potential?




         POTENTIAL
Self-Check: Kinetic or Potential?




         POTENTIAL
Self-Check: Kinetic or Potential?




           KINETIC
Self-Check: Kinetic or Potential?




          POTENTIAL
Self-Check: Kinetic or Potential?




          POTENTIAL
Self-Check: Kinetic or Potential?




            KINETIC
How do cells get their energy?
Cells use chemical energy, that’s the kind stored
in chemical bonds (the electrons)…

…ATP is the Energy molecule
(Adenosine Tri-Phosphate)

The cells break the bonds of the ATP molecule.
This releases a tremendous amount of energy.
The cells use this energy to do their work.
Self Check: Fill In The Blanks
1. Energy is the ability to make something
      move             change
   _________ or __________.
2. There are two basic forms of energy: energy
                            potential
   that is stored, called ____________ energy
   and energy that is being used, called
   ____________ energy.
      kinetic
3. ATP is a cell’s _____________ energy.
                        potential
4. A cell uses the energy stored in ATP by
                   chemical       bonds
   breaking the _________ ________ .
I know what you’re wondering…
Where do cells get this ATP from?
Making ATP
Cells make ATP using their “powerhouses”…




          THE MITOCHONDRION
            (pl. mitochondria)
Cellular Respiration
Mitochondria use a process known as “cellular
respiration” to breakdown glucose and
make ATP.
      C6H12O6 + O2  CO2 + H2O + 36 ATP
Glucose + Oxygen  Carbon Dioxide + Water + 36 ATP
Cellular Respiration
The process of respiration occurs in three steps:
1st – Glycolysis: Glucose is broken into two
  pyruvate molecules, and 2 ATP are produced.

2nd – Kreb’s Cycle: each pyruvate is broken into
  two carbon dioxide molecules, 1 ATP, 3 NADH
  and 1 FADH2.

3rd – Oxidative Respiration: the electron transport
  chain uses the NADH and FADH2 to make 32
  ATP.
Self Check: True or False?
T/F 1. Mitochondria use water, oxygen and
    carbon dioxide to make ATP.
T/F 2. Cellular respiration is the process used
    by mitochondria to produce energy for the
    cell.
T/F 3. The three stages of cellular respiration
    are glycolysis, kreb’s cycle and oxidative
    respiration.
T/F 4. Cells need glucose to make ATP.
T/F 5. Without oxygen, ATP can’t be made.
        C6H12O6 + O2  CO2 + H2O + 36 ATP
ATP without Oxygen
When oxygen is present, cellular respiration
occurs as described; “aerobic” respiration.

When oxygen is absent, cellular respiration
switches to “anaerobic” respiration, or
“fermentation”.
Fermentation
There are two forms of fermentation:
  Lactic acid fermentation:
  ATP and lactic acid are
  produced and builds up,
  causing cramps!


                              Alcoholic fermentation:
                              ATP and ethyl alcohol
                              are produced; cheers!
Self Check: Short Answer
1. What are the two forms of fermentation?
    Lactic acid fermentation, alcoholic fermentation
2. What is the purpose of fermentation?
    To make ATP when there is no oxygen
3. What is the essential ingredient for any form of
   respiration?
          C6H12O6 + O2  CO2 + H2O + 36 ATP



         Glucose
I know what you’re thinking…
Where do cells get their glucose from?

      Well, it depends on whether the
      organism is an…




      Autotroph         or a…     Heterotroph
Autotrophs make their own glucose

• All plants



• Some Protists



• Some Bacteria
Heterotrophs ingest their glucose
• All animals


                        • All fungi
It all starts with the Autotrophs
Heterotrophs may eat other heterotrophs, but
ultimately, all glucose comes from an autotroph.
Autotroph or Heterotroph?




      HETEROTROPH
Autotroph or Heterotroph?




       AUTOTROPH
Autotroph or Heterotroph?




     HETEROTROPH
Autotroph or Heterotroph?




       AUTOTROPH
Autotroph or Heterotroph?




     HETEROTROPH
Autotroph or Heterotroph?




       AUTOTROPH
I know what you’re thinking…
How do autotrophs make their own glucose?




                Glucose
It’s all about chlorophyll…
Chlorophyll is a green pigment that absorbs
sunlight and gets “excited”!




                  Eukaryotes keep their chlorophyll in
                  their chloroplasts.
                  Prokaryotes keep it in their
                  cytoplasm.
Making glucose
Autotroph cells make glucose using their “solar-
powered glucose factories”…




           THE CHLOROPLASTS
Photosynthesis
Chloroplasts use a process known as
“photosynthesis” to make glucose from carbon
dioxide, water and sunlight.

      CO2 + H2O + SUNLIGHT  C6H12O6 + O2

  Carbon Dioxide + Water + SUNLIGHT  Glucose + Oxygen
Photosynthesis
Photosynthesis also takes place in two steps:
1st – Photophosphorylation: Chlorophyll captures
  light energy and uses it to make ATP and
  NADPH.
      *because this step requires sunlight, it is
      also called the “Light Reaction”.

2nd – The Calvin Cycle: The ATP and NADPH
  are used to combine 6 carbon dioxide
  molecules to form one glucose molecule.
     *because this step does not require sunlight,
     it is also called the “Dark Reaction”.
Self Check: Fill In The Blanks
1. Autotrophs use _____________ to make their
                    photosynthesis
   glucose.
                                 water
2. Photosynthesis requires ___________,
   ________ ________ and ____________.
     carbon dioxide              sunlight
3. The two steps of photosynthesis are
                                the Calvin cycle
   __________________ and ______________.
    photophosphorylation
4. _____________ is the green pigment used to
     Chlorophyll
   capture light energy from the sun.
5. The purpose of the light reactions is to make
   ___________ and ________ for the dark
        ATP             NADPH
   reactions.
Consider this…
In nature, all organisms and processes are
intimately connected to each other…

        …how are respiration and photosynthesis
                      connected to each other?
The Yin and Yang of Cell Energy
      C6H12O6 + O2  CO2 + H2O + 36 ATP
Respiration requires           …and respiration
oxygen…                        produces carbon
                                       dioxide!




Photosynthesis              …and photosynthesis
requires carbon dioxide…      produces oxygen!
      CO2 + H2O + SUNLIGHT  C6H12O6 + O2
In Summary
Remember…
- Cells need energy.
- Cells use ATP as their source of energy.
- Cellular respiration uses glucose to make ATP.
- Photosynthesis uses sunlight to make glucose.
- The two processes are intimately connected.

				
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