Download Chemical Reactions

Chemical Reactions
•  A process that changes one set of chemicals
into another set of chemicals.
–  What starts the reaction is called the reactants.
•  Will be located on the left side of the equation.
–  What is produced in the reaction is called the
products.
•  Will be located on the right side of the equation.
Practice
•  What are the product(s) in this formula?
•  What are the reactant(s)?
PHOTOSYNTHESIS
Photo – light
Synthesis- to make
To make food using light
Overview
•  All energy on earth comes from the ___.
•  We depend on: Autotrophs!
•  Autotrophs make their own ________!
–  Plants
–  Algae (underwater plants)
–  Cyanobacteria (photosynthetic bacteria)
Basic Photosynthesis
REACTANTS (go in)
Ø Sunlight energy is
absorbed
Ø Carbon dioxide and
water are used
H2O + CO2 àC6H12O6 + O2
PRODUCTS (come out)
Ø Oxygen and glucose
(sugar) are made
Overview
1)  Plants absorb sunlight energy and convert it to a
usable form
2) Carbon dioxide enters plant through the leaves
and water is taken in by the roots
3) Energy is used to make sugar molecules
4)  Sugar is converted to starch and stored
5) Oxygen is a bi-product
Chloroplasts
•  Organelle in which
photosynthesis takes place
called the CHLOROPLAST
•  Chloroplasts are tiny sacs
of chlorophyll
(green pigment àgives
plants its color!)
Stroma – area
inside chloroplast
that surrounds all
other structures
Thylakoid – flat
sacs that are
surrounded
stroma
Grana – stacks of
thylakoids
Chlorophyll’s job
•  Collects energy
from the sun
•  Plants use this
energy to
change carbon
dioxide and
water into food!
There are 5 basic steps to
photosynthesis
Light (dependent)Reactions
Image from: Biology 11: College Preparation. Pg 74. Nelson, Toronto. 2003.
Happens: ONLY in
sunlight
1.  Light is absorbed
by chlorophyll
molecules
2.  Water is broken
down
3.  Oxygen is released
4.  Generates
molecules of ATP
Light Independent Reactions
Happens: sunlight &
dark
1.  Carbon dioxide is
broken down
2.  ATP changes to
ADP drives the
Calvin Cycle.
3.  Makes SUGAR
(glucose, plant
food)
Image from: Biology 11: College Preparation. Pg 74. Nelson, Toronto. 2003.
Overall Reaction
So what is the equation for photosynthesis?
Light
carbon dioxide + water
glucose + oxygen
Light
CO2 + H2O
C6H12O6 + O2
Where do the reactants
come from?
•  Water enters
the plant from
the roots
•  It travels up
tubes (straws)
in the plant
(xylem)
•  Carbon dioxide enters
the plant through pores
(holes) in the leaf
•  The pores are called
stomata
•  Can you see the
stomata?
•  Are the stoma open or
shut?
•  Why would a plant want
it’s pores closed?
Where do the products go?
•  Oxygen is released
back out of the
stomata
•  Carbohydrates move
through the plant in
tubes called phloem
•  They are stored as
glucose or as starch
or cellulose
These carbohydrates
become our food!
•  They can be stored
in the roots
•  They can be stored
in the leaves
•  They can be stored
in the stems
BONUS QUESTION!
•  What is the name
of the reaction
that builds starch
from many
glucose
molecules?
•  Dehydration
synthesis