Cellular Respiration
You feel weak when you are hungry because food serves as a source of
energy.
How does the food you eat get converted into a usable form of energy for your cells?
Chemical Energy and Food
Calorie – amount of energy needed to raise a
temperature of 1 gram of water by 1 degree Celsius
Cells use all sorts of molecules for food, including
fats, proteins, and carbohydrates.
The energy stored in these molecules varies
because their chemical structures, and therefore
their energy-storing bonds, differ.
Cells break down food molecules gradually and use
the energy stored in the chemical bonds to produce
compounds such as ATP that power the activities
of the cell.
Where do organisms get
energy? Food = chemical
energy
It provides living
organisms with
chemical building
blocks they need to
grow and reproduce
ATP = organic
molecule containing
high energy bonds
powers most cell
activities
Cellular Respiration Overview
Cellular Respiration: Transformation of
chemical energy in food into chemical
energy cells can use
ATP energy
Overall Reaction:
C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP
Glucose + Oxygen Carbon dioxide + Water + Energy
ATP Reminder!ATP = adenosine triphosphate.
This is the compound that directlysupplies the energy to do cellular work.
How ATP Works
The release of one of the phosphate groups makes energy available to do cellular work.
ATP energizes other molecules by transferring one phosphate group.
Cellular Respiration has
Many Steps!
1) Glycolysis
2) Krebs cycle
3) Electron transport
chain
Oxygen and Energy Aerobic- process that requires
oxygen
Some parts of Cellular Respiration
need Oxygen
Both take place in mitochondria
Makes 36 ATP molecules
Anaerobic- process that does
not require oxygen
Some parts don’t need oxygen
Takes place in cytoplasm
Makes 2 ATP molecules
What do you notice?
Cellular Respiration
C6H12O6 + O2 CO2 + H2O + ATP
Photosynthesis
CO2 + H2O + Light C6H12O6 + O2
Photosynthesis vs. Cellular
Respiration The reactants of cellular
respiration are the products
of photosynthesis and vice
versa.
The release of energy by
cellular respiration takes
place in plants, animals,
fungi, protists, and most
bacteria.
Energy capture by
photosynthesis occurs only in
plants, algae, and some
bacteria.
ATP and Glucose Most cells have only a small amount of ATP (enough
to last for a few seconds of activity)
ATP is very efficient at transferring energy but it is not very good at storing energy over long periods of time.
It is more efficient for cells to store energy in a molecule such as glucose.
A glucose molecule has more than 90 times the chemical energy of a molecule of ATP
If our body needs to store energy for longer, we store it as fat
Energy and Exercise
Quick bursts of energy body uses ATP
present in muscles
Exercise longer than 90 seconds cellular
respiration is the only way to continue
generating a supply of ATP
You need oxygen for this
You need to breath!
Cramps while Exercising?
If you don’t get enough oxygen from breathing
your body switches to Lactic Acid Fermentation
Lactic Acid Fermentation gives us energy but
causes lactic acid to build up in our muscles
This causes cramps!
In order to get rid of the
lactic acid you must get
oxygen Breath!
Fermentation
What happens when oxygen isn’t around?
Fermentation
Fermentation – makes energy
from food without oxygen
Alcoholic Fermentation –
yeast and other organisms use
alcoholic fermentation to get
energy
Makes cheese, bread, beer, etc!