Principles of Biology
By
Frank H. Osborne, Ph. D.
Cellular Respiration
Cellular Respiration
Cellular respiration is used to obtain energy.
• The energy is stored in molecular form (ATP).
• The by-products of respiration are carbon
dioxide and water.
• The process of respiration is
carried out by all living cells, all the
time. Even a plant cell in the light will do
photosynthesis in the chloroplasts and
respiration in the mitochondria simultaneously.
Cellular Respiration
Cellular respiration has two phases.
• Anaerobic phase - does not require oxygen
–Fermentation is a partial breakdown of glucose
that provides a little quick energy (2 ATP)
anaerobically.
• Aerobic phase
–Aerobic respiration is complete oxidation of the
glucose molecule. It results in 36 ATP.
–Aerobic respiration is more
efficient than fermentation.
Cellular Respiration
• Cellular respiration has two phases:
anaerobic respiration
aerobic respiration
• Anaerobic bacteria have only the anaerobic
phase. They can obtain energy without oxygen.
• All other cells have both phases. They use
oxygen in the aerobic phase.
• The CO2 released from respiration
is used by plants for photosynthesis.
Cellular Respiration
• Anaerobic respiration is carried out using the
Embden-Meyerhof pathway, commonly known as
glycolysis.
• Anaerobic respiration is found in all cells, even
those that use oxygen.
• Anaerobic respiration is the only type of
respiration found in anaerobic bacteria. These
bacteria do not require oxygen for living.
• Anaerobic bacteria use fermentation for energy.
Cellular Respiration
• Aerobic respiration involves the oxidation of
glucose using oxygen.
• After glycolysis the Krebs cycle is used.
• Molecular oxygen is used as the terminal
electron acceptor for the respiratory chain.
Cellular Respiration
• In humans, muscle cells cannot perform
oxidative phosphorylation fast enough during
vigorous exercise.
• During vigorous exercise the muscles
do fermentation. As a result you get
tired and feel a burning sensation
caused by lactic acid.
• So you rest, and the body removes the lactic acid
from the muscles.
Cellular Respiration
• Sugars and carbohydrates are sources of
energy for the body.
• They can also be converted to fats.
• When there is an excess of carbohydrates in
the diet, the body saves them up in the form of
fats which are stored in fat cells. This leads to
an increase in body fat content.
Topics for First Exam
Chemistry (15)
Cells (13)
Tissues (12)
Photosynthesis (5)
Cellular Respiration (5)
The End
Principles of Biology
Cellular Respiration