Download Cell Respiration

Meanings of Respiration
1. External Respiration – exchange of gasses (O2 and
CO2) in the lungs, between the air and the blood.
2. Internal Respiration - exchange of gasses (O2 and
CO2) in the capillaries, between the blood and the
tissues.
3. Cellular Respiration – Production of cellular
energy by the intracellular breakdown of sugars
Cellular Respiration
• Energy releasing process by which glucose
molecules are chemically broken down to
produce energy in the form of ATP
• ATP is used to do various types of cellular
work (active transport, synthesis,
maintenance, growth, repairing, and muscle
work)
• Glucose – C6H12O6
– 6 atoms of carbon
– 12 atoms of hydrogen
– 6 atoms of oxygen
• O2 – oxygen gas
• CO2 – carbon dioxide gas
• H2O – water
ATP = adenosine triphosphate
ADP = adenosine diphosphate
Pi = phosphate
ADP + Pi
energy
ATP
Aerobic – requiring O2
Anaerobic – not requiring O2
Cellular Respiration
Simplified Formula
C6H12O6 + 6 O2 + 36 ADP + 36 Pi
6 CO2 + 6 H2O + 36 ATP
The Three Stages of Cellular
Respiration
1. Glycolysis (does not require O2).
2. The Krebs cycle (requires O2).
3. Electron transport chain (ETC) (requires O2).
Glycolysis
• One molecule glucose is partially broken down
to 2 molecules of pyruvic acid (3-carbon
molecules).
• Takes place in the cytoplasm.
• Primitive and inefficient process, extracting
only about 5% of the energy in glucose.
• Occurred first in evolution, because the
concentration of oxygen in the air was low.
Fermentation is glycolysis without the
later steps in respiration. But in
fermentation, there is a simpler second
step that does not produce energy:
pyruvic acid is converted to alcohol and
carbon dioxide, acetic acid, or lactic acid.
Fermentation in Different Cells:
• Yeast cells: Glucose  CO2 + Ethanol
• Cider Bacteria: Glucose  Acetic acid
• Sauerkraut Bacteria: Glucose  Lactic acid
Anaerobic respiration in muscle cells:
Glucose  Lactic acid
The Krebs Cycle and the ETC occur
inside mitochondria
mitochondrion
The Electron Transport Chain 1
• The first carrier donates electrons to the next
carrier, and so on down the line. The last
electron acceptor is O2 , and H2O is formed.
• The electron movement provides energy to
move hydrogen ions, pushing them into the
outer compartment of the mitochondria.
The Electron Transport Chain 2
• Hydrogen ions flow back into the inner
compartment through an enzyme called ATP
synthase. This flow causes ATP synthase to
rotate, which puts Pi onto ADP, thus making
ATP.
The Electron Transport Chain
As electrons are transported,
hydrogen is pumped from the
inner compartment to the outer
Hydrogen flows back to
inner compartment,
generating ATP
ATP production from Cellular Respiration
Glycolysis:
2 ATP
Krebs cycle:
2 ATP
ETC:
32 ATP
_____________________
Total:
36 ATP per molecule of glucose
External Respiration
(Respiratory Systems)
• Large aerobic organisms need to take in
oxygen and get rid of CO2. Various
respiratory systems developed in
different animals, depending on their
environment and their life style.
Respiratory Structures
• Lungs - in all vertebrates except fish
• Gills - in fish
• Skin gills - surrounded by pincers Echinoderms/Starfish
• Book gills - between belly plates - some
Arthropods/Horseshoe crab
• Tracheae and spiracles – insects (air tubes
that branch internally)