Cellular Respiration
Chapter 2, Lesson 2
What is Cellular Respiration?
● Body breaks down the food you eat
○ Releases sugars
○ Sugars (glucose) can be broken down further…
● Cellular respiration = the process by
which cells obtain energy from glucose
● Happens only with oxygen!
○ This is called an aerobic process
Storing and Releasing Energy
● Energy is like money!
○ Energy has to be in the right “currency” to use
it.
● When you eat, you add to your energy
savings.
● When your cells need energy, they
“withdraw” it from the savings.
Breathing & Respiration
● We often think of these two words as being the same
thing! They AREN’T!
● Breathing - brings air in and out of your lungs
○
○
○
Oxygen into your lungs
Oxygen is then carried to your cells for respiration
Carbon dioxide comes out of your lungs
● Respiration - uses oxygen to convert sugar into energy
and carbon dioxide
● Breathing & Respiration are related… but not the
same!
Two Stages - Stage 1
● Occurs in the cytoplasm.
● Molecules of glucose are broken down
into smaller molecules.
● No oxygen is needed!
● A small amount of energy is released.
Stage 2
● Takes place in the mitochondria.
● Small molecules are broken down even
more.
● Requires oxygen!
● Releases LOTS OF ENERGY!
Cellular Respiration Equation
● Raw materials (reactants):
○ Glucose - get from the food we eat
○ Oxygen - get from breathing
● Products:
○ Carbon dioxide - leaves when we exhale
○ Water - leaves when we exhale, sweat, urinate etc.
○ ENERGY!! - used for many cell processes
The Two Stages of Cellular Respiration
Comparing Two Energy Processes
● Photosynthesis &
Cellular Respiration can
be thought of as
opposites.
● These two processes
keep the cycle of life
going!
Fermentation
& a Review of Energy for Life
What Happens During Fermentation
● Some things can live without oxygen!
● Fermentation is an energy releasing process
that does not require oxygen.
○ Cells release energy from food without using
oxygen.
● Drawback?
○ Releases less energy than cellular respiration.
Alcoholic Fermentation
● Occurs in yeast and other single-celled
organisms.
● Products:
○ Alcohol
○ Carbon dioxide
○ Small amount of energy
● This process is used by bakers and brewers.
Lactic Acid Fermentation
● Occurs when your muscle cells can’t get oxygen fast
enough to make energy.
● Produces a little bit of energy without using energy.
● Products:
○ Lactic Acid → (what makes your muscles sore!!)
○ Small amount of energy
● Lactic acid eventually breaks down when you have
more oxygen.
Energy for Life
● Energy processes include cellular respiration,
fermentation, and photosynthesis.
● Producers:
○ Plants capture energy using photosynthesis.
○ Plants release energy for cell functions using cellular
respiration.
● Consumers:
○ A person running gets energy using cellular respiration.
○ The person is a heterotroph because they get energy from food.
○ If the person runs to long or too fast, their muscles will use
fermentation to get energy.