Transcript Mid-term Power Point

Metabolic Pathways of Plants
Nathan J. Smith
Undergraduate in WFS
Tennessee Technological University
Cookeville, TN 38501
Project Summary
 Photosynthesis is a highly integrated
and regulated process which is highly
sensitive to any change in
environmental conditions. In order to
achieve this, a plant must have carbon
dioxide, water, light, and
photosynthetic pigments. (Ensminger
2006)
 Problem: If a plant (coleus) will not
photosynthesize in the dark, what will
it do to in order to survive?
Introduction
 Leaves come in many different shapes, sizes, colors,
and types.
 Photosynthesis occurs in the mesophyll cells of
leaves. Mesophyll cells are composed of tiny bodies
called chloroplasts.
 These pigments are used to catch the light energy
needed for photosynthesis to occur.
Introduction Continued
 Starch is a major storage component in plants which
strongly affects how well the plant will mature. (Stark 1992)
 Soluble sugars like sucrose and glucose play a very
important role in plant structure and metabolism. (Ivan
2006)
 Glucose can be converted into starch and stored. Also,
both starch and sucrose can be turned back into glucose
and used for cellular respiration.
 As most plants will store starch, those that do not receive
the proper amount of light will be forced to convert their
starch back into glucose where it will be utilized in cellular
respiration by the mitochondria.
Objective/Hypothesis Statement
 Objective: The object of this experiment is to show how a
plant (coleus) grown in the dark for two weeks will not
photosynthesize and therefore convert its starch back to
glucose in order to perform cellular respiration.
 Hypothesis: I predict the plants grown in sunlight will
photosynthesize and produce starch which will be stored.
The plants grown in darkness will utilize their starch for
cellular respiration. Once the plant uses all its starch, it
should die.
 Null Hypothesis: Both plants will photosynthesize, store
their starch, and grow to maturity.
Methods and Materials
 Materials needed for this experiment are:
- Bunsen Burner
-Two Beakers
- Forceps
- Watch glass or Petri dish
- Light source and dark source
- Boiling water
- Denatured ethanol
- Iodine solution
- Coleus plants
Data Form
Methods Continued
 1) Set up the experiment.
 2) Bring a beaker of water to a boil on the Bunsen
burner and add the coleus leaf from set A (the leaf
which has been exposed to light for two weeks).
 3) Leave leaf in boiling water for a little over one
minute in order to break down the waterproof
layer.
 4) Take the leaf out of the boiling water and place
it into a smaller beaker filled with about 50 ml of
ethanol.
Methods Continued
 5) Place the test tube back into the beaker of hot
water. The ethanol should begin to boil.
 6) After the leaf has lost all pigments, take it out
and place it back into the hot water to rinse the
ethanol off.
 7) Spread the leaf out flat on a Petri dish or watch
glass. Add about five drops of iodine solution to
the leaf and observe what happens. (If starch is
present, the leaf will turn a black/purple color.
 8) Repeat the same process using a leaf from set
B (the leaf left in the dark for two weeks).
Expected Results
 I expect group A to do much better than
group B.
 Group A should photosynthesize and store
their glucose as starch.
 Group B should convert its starch back to
glucose for cellular respiration.
 If Group B stays in the dark for a long time,
the plants will use up all their starch and die.
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Projected Timeline
Timeline
16
14
12
10
8
6
4
2
0
Budget
*Salary- $165
*Nonexpendable- $50
*Expendable- $65
*Indirect Costs - $25
*Travel- $25
Budget
Salary
Inexpendable
Costs
Expendable Costs
Indirect Costs
Travel
The End