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Fighting off the cold |
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Informations |
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Project:
Fighting off the cold |
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Developed By:
Julie Désalliers |
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Type of Project:
Experiment |
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Category:
Life science |
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Class:
Junior |
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Age of Participant:
14 |
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School:
Polyvalente Sainte-Thérèse |
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Teacher:
Thomas Butler |
Project presented at the 1998 North Shore regional
final of the Bell Science Fair
Selected for the 1998 Quebec final (Montreal) of the Bell Super Science
Fair
Selected for the 1998 Pan-Canadian Science Fair in Timmins
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Introduction |
Humans have always had tons of theories about heredity
and genetics. Pythagorus (580 B.C.), for example, believed that sperm
ejaculated into the vagina coagulated to form an embryo. Later, Lamarck
and Darwin (around 1799) proposed their theory of heredity and natural
selection. But it was thanks to Mendel’s chromosome theory and
laws of heredity that the first definitive steps towards developing knowledge
of evolutionary biology were taken. We have since learned that our genetic
information is stored in our genes1, that our genes are made up of DNA,
and that this DNA—discovered by Watson and Crick (1953)—has
the shape of a double helix.
Plants also have genes. Certain varieties of wheat even have genes for
resisting the cold, a very important factor in Canada, given our climate.
(The average temperature in central Canada is approximately 10°C.
We also experience temperatures that range from 26°C to, unfortunately,
-26°C. Growing crops becomes impossible at such temperatures, unless
plants develop some sort of resistance.)
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Is wheat resistant to cold? |
Wheat’s ability to resist the cold is very important because, in
Canada, we grow this grain over more than 12 million hectares (1 hectare
= 100 m x 100 m). Farmers can count on several types of wheat, including
spring wheat (Tricicum astivum Glenlea) and a winter wheat (Tricicum
astivum Frederick), which has a better resistance to cold.
But how can we observe the difference in resistance between winter wheat
(Frederick) and spring wheat (Glenlea)?
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Physical resistance of wheat |
To find out, I conducted several experiments. I began by allowing six
spring wheat and six winter wheat plants to germinate for 10 days at
25°C. I then exposed them to a temperature of 4°C for a period
of four weeks. I took three plants of each type, cut them back to 13
cm and observed their growth for 12 days. Finally, I drew a graph of
the growth rate of the winter wheat vs. that of the spring wheat.
My observations revealed that the winter wheat resisted its four-week
period at a temperature of 4°C because it grew back to its initial
height in only 12 days. The spring wheat, however, did not resist quite
so well, hardly growing all.
I also conducted a second experiment. I placed the three remaining winter
and spring wheat plants in a freezer at -10°C for one week. I observed
that the winter wheat resisted the cold for the entire week, while the
spring wheat turned yellow (a sign of non-resistance).
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Resistance to cold coded in the genes |
The genetic difference between winter wheat and spring wheat can be observed
other than with the naked eye, thanks to a sophisticated technique known
as protein synthesis. A highly complex experiment enabled me to “see” on
paper that the genes for resistance to cold were activated when the variety
of winter wheat (Frederick) was exposed to low temperatures.
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The problem with winter wheat |
As you have realized by now, winter wheat is more resistant. Unfortunately,
farmers don’t seed it because of its low germination rate. Since
only a small percentage of the seeds that are planted actually germinate,
farmers tend to plant more spring wheat. For this reason, researchers
in certain laboratories are trying to make spring wheat more resistant
to cold.
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For greater resistance... |
There are several ways of making wheat more resistant. One method is
cross-pollination, which consists of combining the female cell of one
plant with the male cell of another plant. Although this method can produce
positive results, it is also quite time-consuming.
Recently, a new highly experimental but very useful method was developed:
cloning. It consists of reproducing the genes of a plant to create a
copy containing the same genetic information. The winter wheat’s
gene for resistance to cold could be cloned and then transferred to the
cells of the spring wheat.
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Summary |
We have seen that wheat is an important plant in Canada and that there
are currently two varieties: winter wheat and spring wheat. After conducting
experiments at Polyvalente Sainte-Thérèse and the UQAM
laboratory, I realized that winter wheat really is more resistant to
cold. Unfortunately, its rate of germination is too low for it to be
planted. It would be extremely useful if its genes for resistance to
cold could be cloned and transferred to spring wheat. Quebec has thousands
of square kilometres of fertile land that are not being cultivated because
of low temperatures. Can you imagine how wheat production would increase
in Quebec and the rest of Canada if our spring wheat were resistant to
cold?
1 What is a gene? A gene, like a book, must
be decoded. It is made up of a series of “letters” (ACGT)
called nucleotides, which make up DNA (deoxyribonucleic acid). Once the
DNA is decoded, proteins are formed, giving each of us our respective
characteristics.
RNA (ribonucleic acid) is responsible for decoding DNA in three stages.
First, the messenger RNA carries DNA information using a three-letter
genetic code. Then, the transfer RNA decodes the messenger RNA and delivers
the information beyond the nucleus of the cell. Finally, the ribosomal
RNA carries out the protein synthesis. Protein synthesis involves two
steps: formation and translation. Formation is what was just explained.
Translation involves transforming “words” (made up of the
nucleotides ACGT) into proteins, with the help of ribosomes.
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© 2002, Conseil de développement du loisir scientifique (CDLS). This
document is distributed by the Conseil de développement du loisir scientifique.
For more information, visit our Web site at www.cdls.qc.ca. |
The opinions expressed
in this section are those of the authors and do not necessarily
reflect the opinions of Merck Frosst or its employees. |
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