Cell Overview - Revision
Cellular Respiration
•Cellular respiration is the process
by which organisms break down
energy rich molecules, e.g. glucose,
to release the energy in a useable
form.
•This is not the same as human
respiration - cells do not “breathe”
Equation for Respiration
Respiration Overview
Mitochondria Structure
• Mitochondria are the site of cellular
respiration.
• There can be more than one in each cell.
Cells that need more energy have more
mitochondria.
Draw this:
Not this!
Electron Micrograph of
mitochondria
Mitochondria Structure
• Mitochondria consist of 2 membranes, an
inner and an outer membrane.
• The inner membrane (also called the
christae) is folded many times to increase
its surface area, thus allowing more
respiration to take place.
• Inside the christae is the matrix, it is fluid
that fills this compartment completely and
aids in the respiration process.
Respiration
• There are 4 steps to cellular respiration:
– Glycolysis (occurs in cytoplasm)
• Glucose is broken down into 2 molecules of pyruvate
– Transition Reaction (occurs in the matrix)
• Pyruvate is converted to Co-enzyme A
– Krebs Cycle (occurs in the matrix)
• Series of reactions that produce carbon dioxide, ATP, and
hydrogen
– Electron Transport Chain (occurs in the
christae)
• Hydrogen gas is oxidised to water using oxygen as the final
acceptor.
• Energy is released as ATP
Use this diagram to fill in the “Cell Respiration Concept Map” sheet
2
2
34
A note on ADP and ATP
• ATP is an energy storage molecule that is
more easily converted back into energy than
glucose.
• ATP is converted to ADP to release the
stored energy, which is used for mechanical,
transport and chemical work.
• The ADP is then phosphorylated (has a
phosphate added) to form ATP again.
ADPATP
ATP Yield
• From Glycolysis = 2 ATP
• From Krebs cycle = 2 ATP
• From Electron Transport Chain = 34 ATP
• Grand Total = 38 ATP
• This is per glucose molecule that enters
glycolysis.
• This yield is theoretical only because cells
are not completely efficient.
Anaerobic Respiration
• Different from aerobic respiration because
oxygen is not the final electron acceptor.
• Is not as efficient as aerobic respiration
because the glucose is not completely
oxidised.
Lactic Acid Fermentation
Lactic Acid Fermentation
• Glycolysis doesn’t need oxygen to
produce ATP.
• It makes 2 ATP in total.
• This is less efficient than complete
aerobic respiration but still better
than nothing.
• Glucose is consumed faster than
normal.