2. Thermodynamics recap
• Energy is neither created nor destroyed, it only changes forms!
• Each transfer of energy leads to a little more being unusable!
Takeaway: Every time you eat and convert food energy to cellular
energy, some energy is lost as heat to the universe (increasing entropy)
• This allows our cells to remain organized
3. Photosynthesis recap
• How plants convert energy from the sun to food energy (glucose) in
chloroplasts
• Light-dependent reactions take place in the thylakoid
• Make the necessary ingredients for the light-independent reactions!
• Light-independent reactions take place in the stroma
• Make simple sugars like glucose!
CO2 + H2O C6H12O6 + O2
sunlight
Carbon dioxide + water glucose (sugar) + oxygen
4. thermodynamics
If energy is cycled
between producers and
other organisms, can
you make a prediction
on what the equation
for cellular respiration
would be?
5. Cellular respiration
• Photosynthesis is how plants make their own food (glucose).
• This is why they are called autotrophs!
• How do other organisms get their food?
• Consuming other organisms!
• Why do we even need food?
• Energy is needed to produce work. Work is
anything that an organism does! If we are even
just sitting or sleeping, an organism is doing
work.
• Our cells can’t use the food as it comes, it
must convert it into usable energy. Cellular
energy is ATP
6. ATP
• Adenosine Triphosphate
• Adenine (nitrogenous base)
• Ribose (sugar)
• 3 phosphate groups
• The phosphate groups are unstable
• Energy is stored in the bonds between phosphates
• The 2 end phosphates are easily broken off
• When the bonds are broken, energy is released
• ADP plus Pi is formed and this is recycled to produce more ATP
7. ATP
• ATP is the most important energy molecule needed for survival
• Used for daily function of the cell
• All the chemical reactions in the cell are called its metabolism
8. Cellular respiration
• Cellular respiration (aerobic) and fermentation
(anaerobic) oxidize (removes electrons from) glucose
and convert this chemical energy into ATP
ATP
Sugar
Glycolysis
Anaerobic
Respiration
(Fermentation)
Aerobic
Respiration
ATP
ATP
ATP
ATP
9. glycolysis
• 1st step in aerobic cellular respiration or
fermentation
• Occurs in ALL cell types (including plants and
bacteria)
• 10 reactions
• 2 ATP molecules
• Occurs in the cytoplasm
• Next step varies depending on the presence of
oxygen
Sugar
Glycolysis ATP
10. Aerobic Cellular respiration
• WITH Oxygen
• Most efficient way to produce ATP
• Can produce 38 ATP from each glucose molecule!
• Chemical equation:
• C6H12O6 + O2 CO2 + H2O + ATP
• 3 stages
• Glycolysis (2 ATP)
• Occurs in the cytoplasm
• Kreb’s cycle (2 ATP)
• Occurs in the mitochondria
• CO2 is a waste product
• Electron transport chain (34 ATP)
• Occurs in the mitochondria
• H2O is a waste product
Sugar
Glycolysis
Aerobic
Respiration
ATP
ATP
ATP
ATP
11. Fermentation (Anaerobic respiration)
• WITHOUT Oxygen: Anaerobic respiration
• Glycolysis
• Fermentation
• Occurs in the cytoplasm like glycolysis
• Produces 2 ATP per glucose molecule
• 2 Types of fermentation
• Alcoholic
• Yeast and bacteria
• Ethanol and CO2 are byproducts
• Lactic acid
• Muscle cells (during strenuous exercise – oxygen debt)
• Lactic acid is a byproduct
Sugar
Glycolysis
Anaerobic
Respiration
(Fermentation)
ATP
ATP
13. Photosynthesis and Cellular respiration
• OPPOSING REACTIONS!
• Photosynthesis
• Carbon dioxide plus water yields (in the presence of
sunlight) glucose plus oxygen
• CO2 + H2O C6H12O6 + O2
• Cellular respiration
• Glucose plus Oxygen plus ATP yields Carbon Dioxide
plus Water
• C6H12O6 + O2 CO2 + H2O
sunlight