Cell Processes
Key Concepts
• Explain how the sun supplies living things
with the energy they need.
• Describe what happens during the process
of photosynthesis.
• Describe the events that occur during
respiration.
• Tell what fermentation is.
Key Terms
• Photosynthesis
• The process by which a cell
captures energy in sunlight and
uses it to make food.
• Autotroph
• An organism that makes its own
food.
• Heterotroph
• An organism that cannot make
its own food.
• Pigment
• Colored chemical compounds
that absorb light.
Key Terms
• Chlorophyll
• The main photosynthetic
pigment in chloroplasts.
• Stomata
• Small openings in the
undersides of leaves where
CO2 enters and O2 exits.
• Respiration
• The process by which cells
obtain energy from glucose.
• Fermentation
• An energy-releasing process
that does not require
oxygen.
Introduction
• Every living thing needs energy.
• All cells need energy to carry out
their functions.
– Making proteins
– Transporting substances into and out of
the cell
• The sun supplies energy for most
living things, directly or indirectly.
Sources of Energy
• Autotroph
• Heterotroph
• An organism that
makes its own food.
• An organism that
cannot make its own
food.
• Ex. plants, algae,
some bacteria
• Ex. animals, fungi,
some bacteria
Photosynthesis
What is Photosynthesis?
• The process by
which a cell
captures energy in
sunlight and uses it
to make food.
• Photo – light
• Synthesis – putting
together
Two Stages of Photosynthesis
• Capturing the
Sun’s Energy.
• Using Energy to
Make Food.
Stage 1: Capturing the
Sun’s Energy
• In plants, this
energy-capturing
process occurs
mostly in the
leaves.
• Chloroplasts,
containing
chlorophyll,
capture energy
from sunlight.
Stage 2: Using Energy
to Make Food
• The cell uses the
captured energy to
produce sugars.
• Water and Carbon
Dioxide (raw
materials) are needed
for this stage.
• The raw materials
undergo a complex
series of chemical
reactions producing
sugar and oxygen.
Animation of
Photosynthesis
• http://www.growingthenextgeneration.com/ag
rium-games/Animation/index.htm
The Chemical Equation
for Photosynthesis
Simplifying the Equation
• Raw Materials – Water & Carbon Dioxide
• Catalyst – Light Energy
• Products – Carbohydrates (Sugars) & Oxygen
Respiration
What is Respiration?
• The process by which
cells obtain energy
from glucose.
• Cells break down
simple food
molecules such as
sugar and release the
energy they obtain.
Breathing and Respiration
• Respiration has two meanings.
– “Breathing” – moving air in and out of your
lungs.
– “Cellular Respiration” – respiration process
that takes place inside cells.
• The connection – “breathing” brings
oxygen into the body needed for “cellular
respiration” to occur.
Two Stages of Respiration
• Breaking down
glucose.
• Breaking down
glucose even more.
Stage 1: Breaking Down
Glucose Molecules
• This first stage
takes place in the
cytoplasm of the
organism’s cells.
• Oxygen is not
involved in this
part of the process
and only a small
amount of energy
is released.
Stage 2: Making Small Glucose
Molecules Smaller
• This second stage
takes place in the
mitochondria of
the organism’s
cells.
• Oxygen is required
in these chemical
reactions and a
great deal of
energy is released.
Animation of Respiration
• http://www.sumanasinc.com/webcontent/anima
tions/content/cellularrespiration.html
• Click on “The Big Picture”. (You can add subtitles!)
The Chemical Equation
for Respiration
Simplifying the Equation
• Raw Materials – Glucose & Oxygen
• Catalyst – Stored Energy
• Products – Carbon Dioxide, Water & Energy (ATP)
What’s the Connection?
Photosynthesis and
Respiration are Opposites
Fermentation
What is Fermentation?
• Respiration without oxygen!
Fermentation Defined
• An energy-releasing process that does not
require oxygen.
• Some single-celled organisms live where
there is no oxygen, such as deep in the
ocean or in the mud of lakes or swamps.
• The amount of energy released from each
sugar molecule is much lower than the
amount released during respiration (with
oxygen).
Types of Fermentation
• Alcoholic
• Lactic Acid
Alcoholic Fermentation
• Yeast and other
single-celled
organisms break
down sugars.
• This is often called
alcoholic fermentation
because alcohol is one
of the products.
• Carbon dioxide and a
small amount of
energy are also
products.
Carbon dioxide in yeast causes
bread to rise and causes the
bubbles in alcoholic drinks
like beer and wine.
Lactic Acid Fermentation
• Takes place at times in
your body.
• Muscle cells use up oxygen
faster than it can be
replaced.
• When cells lack oxygen,
fermentation occurs.
• Lactic acid is a product of
fermentation within
animal cells.
– painful sensation in your
muscles
– muscles feel weak and
sore
Photosynthesis and
Respiration
Cell processes that affect the function
of the entire organism.