Transcript Cellular Respiration

Cellular Respiration
Respiration: An Overview
• The process by which
cells break down food
sources such as glucose,
fats, and protein and
release their stored
energy.
• Two main types
– Anaerobic – no oxygen
required
– Aerobic – requiring oxygen
• Both forms produce
energy storage molecules
called ATP – adenosine
http://www.chemistry.wustl.edu/~courses/genchem/LabTutorials/Cytoc
triphosphate.
hromes/images/flowchart1.jpg
Anaerobic Processes
• No oxygen is
required for these
processes.
• Includes
glycolysis, the
breakdown of
glucose, and
fermentation.
• Some bacteria
and yeast are
examples of
anaerobes.
http://www.biol.vt.edu/research/images/C._perfringens_in_mac._jpg.jpg
http://www.utoronto.ca/greenblattlab/images/a/yeast%201.jpg
Glycolysis
• Occurs in the
cytoplasm.
• Breaks down glucose
into 2 molecules of
pyruvate (3-carbon
structures)
• 2 ATP molecules are
formed.
• 2NADH energy shuttles
are also formed.
• This pyruvate is further
metabolized during
fermentation
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/enyld1.gif
Fermentation
• Pyruvate can be metabolized by:
– Alcoholic fermentation
– Lactic acid fermentation
• AF produces ethyl alcohol and
CO2 – yeast can ferment apple
juice to fill a balloon.
• LAF produces lactic acid. It can
build up in muscles during
strenuous exercise and cause
burning and soreness.
Aerobic Processes
• Requires oxygen.
• Most organisms are aerobes.
• Equation for Aerobic respiration:
C6H12O6 + 6O2  6CO2 + 6H2O + Energy
http://www.oum.ox.ac.uk/thezone/animals/life/images/excrete.gif
• Based on this equation – Why do we breathe?
The Mitochondria
• If O2 is present following
glycolysis, pyruvate is
modified and enters the
mitochondria.
• Here food is broken down
completely into CO2.
• Energy storage molecules
like NADH and ATP are
produced. This is why the
mitochondria is called the
power house of the cell.
The Role of Oxygen
• Energy carriers like
NADH drop off
electrons and as
they “fall” to
oxygen during
metabolism energy
is stored in a
payload of ATP.
• Oxygen picks up
electrons and
hydrogen ions to
form water.
Energy
from
electron
s
ATP
ATP
ATP
O2
H2
O
ATP: Adenosine Triphosphate
• ATP is the cells
energy currency.
• Cellular work such as
metabolism,
transport, and
movement is
powered by the
breakdown of ATP.
ATP Structure
– Ribose – a 5-carbon
sugar
– Adenine – a N-base
– 3 phosphate groups
ATP / ADP Cycle
• ATP is constantly being used and remade in
the cell.
• Energy is released or stored by breaking or
making a phosphate bond.
http://www.columbia.edu/cu/biology/courses/c2005/purves6/figure06-09.jpg
Summary of Cellular Respiration
Respiration
Process
Where
Process
Occurs
Anaerobic
Glycolysis &
Cytoplasm
Fermentation
Aerobic Krebs
Cycle and
Mitochondrion
Electron
Transport
Net Gain of
ATP
Per Glucose
2 ATP
36 ATP