Chapter 4: Energy and Cells

1
Chapter 4 Energy and Cells

• Section 4-1
• Chemical Energy and Its Use

2
What is ENERGY?

• Energy is the ability to do work
• Potential energy stored energy
• Kinetic energy the energy of movement
• Potential energy is converted to kinetic energy
  (think rollercoaster)
• In cells, potential energy is in chemical bonds

3
Rubber Band Activity

• With your partner, make a labeled drawing that
  shows
• How work can be done on the rubber band in such a
  way that it stores energy
• How that stored energy can be released to do work

4
Cells and Energy

• All energy starts at the sun
• Cells have a compound called ATP (adenosine
  triphosphate) that works like a battery
• Three compounds to know
• ATP adenosine triphosphate
• ADP adenosine diphosphate
• AMP adenosine monophosphate

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ATP
6
AMP ? ADP ? ATP

• Takes a significant amount of energy to attach a
  phosphate group to AMP to make ADP
• Even more energy needed to make ADP to ATP
• Energy is stored in the phosphate bonds, just
  like electricity in a battery

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How does all this happen?

• Enzymes that require energy have binding sites
  for ATP and similar energy-carrying molecules
• When energy is needed to complete a reaction, one
  phosphate group breaks off ATP converting it to
  ADP dephosphorylation
• ADP can now be phosphorylated

8
Releasing Energy from Food

• Animal cells get energy needed for
  phosphorylation from food
• The reaction of glucose and oxygen in living
  cells produces CO2 and H2O, with lots of energy
  given off
• This energy is trapped by ATP so that it does not
  burn up the cell

9
Cellular Respiration

• General equation
• C6H12O6 6O2 ? 6CO2 6H2O
• Breaking the chemical bonds between the atoms in
  the glucose molecule releases the energy