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					            What Molecules Give Flowers Their Colors?


Materials Needed:
mortars and pestles (VWR catalog numbers 50420-201 and 50420-405)
dropper bottle with acid (0.01M HCl, or use vinegar)
dropper bottle with base (0.01M NaOH, or use baking soda in water, not
baking powder)
squeeze bottle with water
a dropper
plastic cups
a tablespoon



Notes:
We purchased all our plastic bottles from US Plastic Corp 1-800-537-9724



The Science Behind the Investigation:
The colors of flowers are from colored molecules (pigments). Sometimes the
same colored molecule is responsible for different flower colors. A red rose
is crushed in water to extract the colored molecules. The molecules are dark
red. When acid is added to the colored molecules they turn pink or orange.
This is because acid is adds a hydrogen atom to a colored molecule turning it
pink or orange.

When a base is added to the colored molecules they turn purple or blue. In
bases, the hydrogen atom falls off the colored molecules, which makes them
purple/blue. Thus molecules can turn different colors with a very small
change in structure.
The Biochemistry Discovery Lab project has been funded by
generous support from:

The National Science Foundation: The material is based upon
work supported buy the National Science Foundation Grant No.
9814954.
Any opinions, findings, and conclusions or recommendations
expressed in this material are those of the author(s) and do not
necessarily reflect the views of the National Science Foundation
(NSF).

The Pfizer Foundation and the Camille and Henry Dreyfus
Foundation, Inc.
The Pfizer Foundation Biochemistry

Discovery Lab

What molecules
give flowers
their colors?




©2001 New York Hall of Science
Colored molecules give flower petals their color.




   Collect colored molecules
    from a flower petal and           Molecules are tiny
   make them change color.            particles that make
                                      up all living things.




Find out how molecules give
  flowers different colors.
               How to collect colored molecules

                                     Colored molecules give
                                      the petals their color.




                                                                                                           e s.
                                          C ol




                                                                                                         ti m
                                           or
                                             ed




                                                                                                    of
                                                 m
     Pick a petal from the flower                    o le
                                                            cul                              li o
                                                                                                    ns
                                                                  e s m a g n ifi e d m il
       or pick up a loose petal.



Tear the petal into small pieces
and put them in the mortar.
        Fill the spoon to the     Add the water to the petal.
          brim with water.




Grind the petal until the water
is as dark as the petal.

Push down while you                             It's important that
grind in a circle.                              you get the water
                                                     really dark.
   Some of the colored molecules from the petal are now in the water.




                                                                                                            e s.
                                           C ol




                                                                                                          ti m
                                            or
                                              ed




                                                                                                     of
                                                  m
                                                      o le                                           ns
                                                             cul                              li o
                                                                   e s m a g n ifi e d   m il




                                        Divide the colored molecules
                                        between 3 cups.




   Suck up the
colored molecules
 with a dropper.
           How to make the molecules change color

  Add acid to one cup of colored                Add base to another cup of colored
 molecules until they change color.              molecules until they change color.




This acid is weak                                 A base is
 like vinegar, so       id                      the opposite         e   s
  it is harmless.         ac                     of an acid.          ba




                                                      Compare with the cup that
 Compare with another cup to see                     has not been changed to see
   the color change more easily.                    the color change more easily.



                    What colors did you make the molecules change to?



  Did you make the color of a crocus                           or a tulip?
         How do the molecules change color?

In acid, the molecules              In base, the molecules
   are these colors:                   are these colors:
                                                                  You may
                                                                have made
                                                                  green or
                                                                   yellow
                                                                 molecules
                                                               if you added
                                                               a lot of base.
 because they have                    because they have
   this structure:                      this structure:

                                                               These colors
                                                                come from
                                                                other kinds
                                                                of colored
                                                                molecules.




       Can you spot the tiny difference between the two
       molecule structures above? (clue: look at the )
    This tiny change in structure causes a big color change.
How do these molecules give flowers different colors?

Flowers with acid in their petals                      Flowers with base in their petals
are these colors                                       are these colors




tulip

                                                       iris




rose                                                   crocus




because their                                          because their
colored molecules                                      colored molecules
are like the ones                                      are like the ones
you made with                                          you made with
acid:                                                  base:



                       C ol
                              o re d m o l e c u l e
                                                                             C ol
                                                                                    o re d m o l e c u l e
Change one of your
colors to another color
by adding acid or base.




           Just like you can change the color by adding acid or base,
  some flowers can change color by changing the petals between acid and base.




                   acidic petals              basic petals
   Flowers come in more colors than the ones you made.
These other colors are from other kinds of colored molecules.




        Many colored molecules combine together to
       make all the different flower colors that we see.
Do you have a question about molecules and flowers?



   Maybe you can find the answer by        Ask a staff person if
     experimenting some more.                you need help.




When you are done, please throw       ... and wipe out the mortar
    the cups in the trash ...                  with a tissue.
The Biochemistry Discovery Lab project has been funded by
generous support from:

The National Science Foundation: The material is based upon
work supported buy the National Science Foundation Grant No.
9814954.
Any opinions, findings, and conclusions or recommendations
expressed in this material are those of the author(s) and do not
necessarily reflect the views of the National Science Foundation
(NSF).

The Pfizer Foundation and the Camille and Henry Dreyfus
Foundation, Inc.
The Biochemistry Discovery Lab project has been funded by
generous support from:

The National Science Foundation: The material is based upon
work supported buy the National Science Foundation Grant No.
9814954.
Any opinions, findings, and conclusions or recommendations
expressed in this material are those of the author(s) and do not
necessarily reflect the views of the National Science Foundation
(NSF).

The Pfizer Foundation and the Camille and Henry Dreyfus
Foundation, Inc.

				
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