Biology
The Working Cell: Energy From Food
Sunlight Powers Life
There are 2 main types of organisms:
1. Autotrophs are organisms that make their own food from CO2 and
an energy source such as sunlight. Ex Plants, algae, and some
bacteria.
• Autotrophs are the producers b/c they produce their own food &
food for other organisms (they do NOT produce their own
energy).
http://www.google.com/imgres
There are 2 types of autotrophs:
• Photoautotrophs: organisms that use sunlight
(photosynthesis) to produce their own food (plants,
algae, and some bacteria).
http://ashraf.shafaki.googlepages.co
m/palm-tree.jpg/palm-tree-full.jpg
http://gas2.org/files/2008/03/algae2.jpg
http://www.clcbio.com/scienceimages/cya
nobacteria.png
• Chemoautotrophs: organisms that use inorganic
chemicals/compounds (chemosynthesis) to produce
their own food (bacteria).
http://jk169.k12.sd.us/images/Escherichia
_coli1355024.300a%5B1%5D.jpg
Heterotrophs are organisms that
cannot produce their own and must
consume (eat other organisms);
therefore they are consumers. Ex
animals, fungi, and many unicellular
organisms.
http://worldanimalfoundation.homestead.
com/000802_c824_0023_csls.jpg
http://faculty.mccfl.edu/rizkf/OCE100
1/OCEnotes/shark2.jpg
• All organisms perform some type of
cellular respiration
– Conversion of sugar & O2 into usable
chemical energy (ATP)
– By-products are CO2 & H2O
http://www.tomatosphere.org/teacher-resources/teachers-guide/grades-8-10/images/photosynthesis-respiration.jpg
Energy Terms:
• Kinetic energy: energy of motion
• Potential energy: stored energy
• Thermal energy: random molecular motion;
when transferred produces heat
• Chemical energy: form of potential energy
(macromolecules & ATP)
• Calorie: amount of energy needed to raise the
temp of 1 g of H2O by 1˚C; kilocalories = 1,000
cal
• Cellular respiration is a slow ‘burn’ where heat
is produced.
ATP
• Life depends on energy. Compounds that
store energy: ATP, NADPH, NADH, & FADH2.
• ATP= adenosine triphosphate is the energy
currency of the cell (cash of the cell; main
energy of the cell for chemical reactions)
• Every time a bond holding a phosphate group
(PO3) is broken energy is released; therefore
every time ATP losses a PO3, energy is
released.
• ATP can be used for ALL types of cellular
work.
ATP is constantly needed b/c
cells are constantly working.
ATP is continuously broken
down and recycled very
rapidly (used and remade).
Energy for
chemical
reactions 
Energy from
chemical
reactions 
http://library.thinkquest.org/C006669/media/Biol/img/atp_cycle.gif
Cellular Respiration
• Cellular Respiration is the process of
breaking down glucose molecules
through a series of steps to release
energy.
– This produces ATP.
– Occurs in the mitochondria
• This can occur in the presence of O2
(aerobic respiration) or without O2
(anaerobic respiration).
• Aerobic respiration produces 36 ATP molecules
whereas anaerobic respiration produces only 2
ATP.
The overall equation of cellular respiration:
C6H12O6 + 6 O2 
6CO2 + 6H2O + energy
• Metabolism: all of the cell’s chemical reactions
http://www.google.com/imgres
Mitochondria (Sing. Mitochondrion)
•Double membrane
(outer & inner); both
involved in cellular
respiration
•Cristae: folds of
inner membrane
(increasing surface
area)
•Matrix: space within
the inner membrane
http://www.cartage.org.lb/en/themes/sciences/zoology/AnimalPhysiology/Anatomy/AnimalCellStructure/Mitochondria/mitochondria.jpg
There are 3 Phases of Aerobic Respiration:
1. Glycolysis:
• Whether the organism is aerobic or
anaerobic, that organism will undergo
glycolysis. This is always the 1st step!
• Glucose is converted to pyruvate (a 3-C
compound) and 2 ATP are released.
• This occurs in the cytoplasm
• This occurs in 10 steps; 2 phases
• The final results are: 2 NADH, 2 ATP,
and 2 pyruvate
2. Krebs Cycle:
•
This is a.k.a. the citric acid cycle
•
Pyruvate is converted into acetyl-CoA and
CO2 is released
•
Acetyl-CoA enters the Krebs cycle
•
This occurs in the mitochondria (matrix)
•
2 ATP, NADH, and FADH2 are released.
•
For every glucose molecule, 2 pyruvate are
produced.
•
1 ATP is made for each pyruvate; therefore a
total of 2 ATP are made.
3. Electron Transport:
•
Both NADH and FADH2 enter the electron transport
•
This occurs in the mitochondria (cristae)
•
This is the only part that REQUIRES OXYGEN.
•
Prior to this ONLY 4 ATP have been made, yet a total
of 36 ATP can be made during aerobic respiration.
That means 32 ATP can be made here. This is the
cash cow of cellular respiration!
•
Energy is transferred from NADH and FADH2 to
ATP.
•
Water is produced as a by-product as well as heat.
http://fig.cox.miami.edu/~cmallery/150/makeatp/c9x6cell-respiration.jpg
Anaerobic Respiration (w/o O2):
• Fermentation is the extraction of energy from
pyruvate without O2.
• Alcohol fermentation is the conversion of
pyruvate to CO2 and ethanol (yeast, a
unicellular fungi, performs this).
• Lactic acid fermentation is the conversion of
pyruvate to lactic acid during strenuous
exercise when there isn’t enough O2 (animal
muscle cells perform this).
– This is why muscles become fatigued and sore
after strenuous exercising.
• Calories are the amount of heat energy
needed to raise the temperature of 1 gram of
water 1 degree C.
– This is the energy contained in food substances.
http://www.google.com/imgres
THE END!
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This slide show was developed by Dana Halloran,
Cardinal Mooney High School, Sarasota, FL.
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Used with her personal permission,
adapted and amended by Rosa Whiting,
Manatee School for the Arts, Palmetto, FL.