Cells capture and release energy.
Chapter 2 – Section 2 Notes
PHOTOSYNTHESIS
 “Photo-” = light
 “-syntesis” (synthesize) = to make something
 Definition – a step by step process that a plant uses
to make GLUCOSE (sugar) from light
 Job is done in the CHLOROPLAST – specifically in
the CHLOROPHYLL (light absorbing chemical
inside the choloroplasts)
PHOTOSYNTHESIS Steps
 Step one
Plants collect CO2 (Carbon Dioxide) from the air
and H2O from their roots to go inside the
Chloroplasts
 Step Two
Chloroplasts use sun / light and a Chemical
Reaction takes place to change the molecules
 Step Three
The elements rearrange and form GLUCOSE
(sugar) and OXYGEN (waste for the plant)
PHOTOSYNTHESIS in Action
 (see page 49 in the book)
“makes”
6H20 + 6CO2 + light
C6H12O6 + 6O2
Chemical Equation for Photosynthesis
 It takes, 6 Carbon Dioxide molecules and 6 water molecules being
exposed to light to make just one molecule of Glucose and 6
Oxygen molecules.
 http://www.classzone.com/books/ml_science_comp/page_build.cfm
?id=none&mod=1#
 BrainPop Video
Stop for now
All cells make and use energy
Two Types of Energy
Making and Releasing
Cellular Respiration
Fermentation
Requires Oxygen
NO Oxygen
Required
CELLULAR RESPIRATION
Uses Glucose = “Cell Food”
Chemical Energy is stored in bonds
between the elements
It requires Oxygen in order to work and
releases LOTS of usable energy
Cellular Respiration Steps
Step one
All cells collect “Carbohydrate” (Glucose) and
Oxygen (leftovers from Photosynthesis in plants)
and starts to break apart the “Carbohydrate”.
Step Two
Mitochondria takes the “carbo-chunks” and has
the oxygen break them into separate elements
to be rearranged.
Step Three
Chemical Energy gets released, and H2O and
CO2 are made from the rearranged elements.
CELLULAR RESPIRATION in Action
(see page 51 in the book)
“makes”
C6H12O6 + 6O2
6H20 + 6CO2 + Energy
Chemical Equation for Cellular Respiration
 It takes, just one molecule of Glucose and 6 Oxygen
molecules to make 6 Carbon Dioxide molecules and 6 water
molecules with lots of Energy released to the cell to be used.
Now Put them together….
Photosynthesis and Cellular Respiration Cycle
Not quite done….
Fermentation
Basically the same as Cellular Respiration…just
different in that NO Oxygen is needed to get the
Energy
It only releases a small amount of Energy
Does NOT happen in the Mitochondria, it
happens in the Cytoplasm
Two Types of Fermentation…
1. Alcoholic Fermentation
 “Sugar” is changed into an alcohol and CO2
without Oxygen being used
 Example: Bread (made with flour, milk and
sugar and yeast) – They have a Chemical
Reaction and the small amount of alcohol
evaporates and the CO2 makes the
“bubbles” in the bread
Two Types of Fermentation…
Type Two
2. Lactic Acid Fermentation

“Carbohydrates” are broken apart releasing their Energy –
without Oxygen- and an acid is left

Examples: Yogurt (sits only a short time), Cheese (left to sit a
long time) and Sourdough bread (made with milk) or the sugar
“Lactose” as the “sugar / carb”.

Human Example: Exercising for a long time / distance…you
will use up your Oxygen supply in the muscle and have to do
Fermentation to make a little emergency energy. You feel
“sore / pain / burn” sensation – this is the Lactic Acid build up.
See BrainPop video…