Download Cellular Respiration - Telluride Middle/High School

Cellular Respiration
Biology
Why is Respiration
Important?
§  In addition to photosynthesis plants use
oxygen in the air (or water) to turn the
food (glucose) made during
photosynthesis into energy. This process
of using oxygen to release energy from
food is called:
cellular respiration
Interest Grabber
§  What kind of organisms undergo cellular
respiration?
§  All organisms including photosynthetic
organisms, undergo cellular respiration as
long as oxygen is present
Cellular Respiration
C6H12O6 + 6O2
6CO2 + 6H2O + Energy (ATP)
Connection
§  How are the
products of
photosynthesis and
respiration related?
§  The products of
photosynthesis
are the starting
materials for
respiration
Photosynthesis vs.
Respiration
Photosynthesis
§  Food synthesized (made)
§  Energy from sun stored in
glucose
§  CO2 taken in
§  Oxygen given off
§  Produces sugars
§  Requires light
§  Occurs only in the presence
of chlorophyll
Respiration
§  Food broken down
§  Energy in glucose
released
§  CO2 given off
§  Oxygen taken in
§  Produces CO2 and H2O
§  Does not require light
§  Occurs in all living cells
Chemical Pathways
§  Cells don t burn glucose
§  They gradually release the energy from
glucose and other food compounds
§  The process begins with a pathway
called GLYCOLYSIS.
§  Glycolysis releases only a small amount of
energy (net yield of 2 ATP)
Glycolysis
§  Process in which one
molecule of glucose
is broken in half
§  Occurs in the
cytoplasm of the cell
§  This is an anaerobic
process
§  Produces two
molecules of pyruvic
acid, 2 NADH, and 4
ATP
Glycolysis
§  At the pathway s beginning, 2 molecules of
ATP are used up
§  These 2 molecules should be looked at as an
investment
§  So, 2 molecules are used and 4 are produced,
which gives the cell 2 net ATP molecules
Glycolysis
§  This process seems like it doesn't t
create very much energy
§  But…the cells are able to finish the
process so fast, that they can create
thousands of ATP molecules in just a few
milliseconds
§  Watch:
http://www.science.smith.edu/departments/Biology/Bio231/
glycolysis.html
The Krebs Cycle
§  In the presence of oxygen, pyruvic acid produced
in glycolysis passes to the second stage of cellular
respiration
§  The Kreb s Cycle (also known as the Citric Acid
Cycle) occurs in the mitochondria of the cell
Krebs Cycle
§  During the Krebs cycle the following
occurs
§  Pyruvic acid is broken down into carbon
dioxide in a series of energy-extracting
reactions
§  NADH, FADH2, CO2 and ATP
§  A total of 2 ATP are created from this stage
§  Watch:
http://www.youtube.com/watch?
v=hw5nWB0xN0Y
Krebs Cycle
§  Every time you exhale, carbon dioxide is
released
§  This carbon dioxide is produced by the
Krebs Cycle
§  The ATP produced is used for cellular
activities
Electron Transport
§  Electrons passed around during the Krebs
Cycle to the electron transport chain
§  The electron transport chain uses the highenergy electrons from the Krebs Cycle to
convert ADP into ATP
§  A total of 32 ATP are created in the
mitochondria during this stage of resp.
§  Watch: http://www.youtube.com/watch?v=xbJ0nbzt5Kw
Electron Transport Chain
Activity (see handout)
§  Procedure
1.  Predict how exercise will affect your body s production of
Carbon Dioxide (CO2)
2.  In one test tube put 10 ml of water and 4 drops of
bromothymol blue solution
§  Bromothymol turns yellow or green in the presence of
CO2
3.  Partner 1 will take a straw and place it in the test tube.
Partner 2 will act as a timer during this step.
4.  SLOWLY blow air in the straw while being timed.
5.  When the solution changes color, your partner should say
stop, and then record how long the color change took.
6.  Rinse out your test tube with water.
7.  Repeat steps 2-6 for partner 2, with partner 1 timing.
Activity
§  Procedure-Continued
8.  Rinse out the test tube.
9.  Refill with 10 ml of water and 4 drops of
bromothymol blue.
10. Partner 1 needs to jog in place or do jumping
jacks or push ups for 1 minute.
11. Repeat the procedure of blowing in the straw
slowly and timing for color change for partner 1.
12. Record how long the color change took.
13. Repeat steps 8-12 for partner 2 and record.
Activity
§  Answer the following questions with the
data you recorded.
§  How did exercise affect the time for the
solution to change color?
§  What process in your body produces carbon
dioxide? How does exercise affect this
process?
Fermentation
§  If oxygen is not present, glycolysis is followed
by a different pathway called FERMENTATION
§  Fermentation releases energy from food
molecules in the absence of oxygen
Fermentation
Alcoholic Fermentation
§  Produces carbon dioxide and ethyl alcohol as
wastes
§  This is what is produced when yeast is used
to make bread
§  When the yeast in the dough runs out of air, it
begins to ferment and produces bubbles of
carbon dioxide to rise the dough
Pyruvic Acid + NADH = Alcohol + CO2 + NAD+
Lactic Acid Fermentation
§  Produces lactic acid and NAD+ as wastes
§  Produced in your muscles during rapid
exercise when the body cannot supply enough
oxygen to the tissue
Pyruvic Acid + NADH = Lactic acid and NAD+
Quick vs. Long Term Energy
§  The body provides enough
ATP to last about 90
seconds-Quick Energy
§  Enough time for a runner to
finish a 200-300 meter dash
§  Fermentation produces
lactic acid as a by product
§  Getting rid of lactic acid
requires oxygen
§  Thus a runner breathes
heavily at the end of the race
to rid the muscles of lactic
acid that built up
Quick vs. Long Term Energy
§  How about when you need
energy for a long time?
§  The body relies on cellular
respiration to release energy
more slowly
§  This is why athletes must
pace themselves over a long
race---why?
§  To allow oxygen to fuel the
process of cellular respiration
and make more ATP!!!