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Team Members:
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Team Number: 112 School Name: Tularosa High School Area of Science: Biology Project Title: Predicting the rate of spread of the Treacher's Collins disease through a fixed population Project Abstract: http://mode.lanl.k12.nm.us/97.98/abstracts/112.html Interim Report: http://mode.lanl.k12.nm.us/97.98/interims/112.html Final Report: http://mode.lanl.k12.nm.us/97.98/finalreports/112/finalreport.html
How to track the birth defect Treacher Collins through a set
population over a period of generations.
Background
We decided to do our project on this because one of team members
has the recessive gene and his brother has the dominant gene. Genetics is
the branch of biololgy dealing with the principles of heredity. Human
characteristics are determinded by strands of codons. Codons are three
chemical bases that form the arrangement for a specific amino acid in
protein synthesis. These codons specify the insertion of an amino acid
in a specific position in the structure during protein synthesis. In DNA
strands the first codon is always AUG. AUG stands for adenine, thymine,
and guanine. These strands always end in one of three combinations. When
there are more or less than three compounds in a codon, codons are in the
wrong order, or an ending codon comes too early in the strand a defect can
occur. Treacher Collins occurs when an ending codon comes too early. A
genetic code is a various combination of nucleotides which occur in DNA or
RNA molecules of a chromosome. It also determines the make-up of genes.
A gene influences the inheritance and development of some character. A
nucleotide is a group of compounds consisting of a sugar, phosphoric acid,
and nitrogen base. It also determines the structure of genes. DNA is a
nucleic acid in the chromatin of all living cells that carry genetic code.
Chromatin is a protein substance found in the cell nucleus which absorb
strains and form chromosomes. Nucleic acid is a compound that combine
with proteins in cells.
Treachers Collins is a birth defect also known as Mandibulofacial
Dysostosis. Someone named Thomson reported the first case in 1846. They
associated the disease with Treachers Collins, who reported two other
cases in 1900. Francesschetti and Klein made more extensive research.
Since 1940 there have been more than 250 that have been reported. The
people can develop respiratory problems, because of their narrow airways.
In some cases it requires a temporary tracheastomy, most of the people
have normal intelligence. Some have a type of deafness, but it is
correctible by hearing aids or surgery. Growth of facial bones in
childhood results in cosmetic improvement that could be enhanced by
plastic surgery or other types of surgery.
Genetics is the scientific study of how physical, biochemical, and
behavioral traits are transmitted from parent to offspring. The word
itself was coined in 1906 by British biologist William Bateson. Genetics
are able to determine the mechanisms of inheritance because the offspring
of sexually reproducing organisms do not exactly resemble their parents,
and because some of the differences and similarities between parents and
offspring recur from generation to generation in a repeated pattern. The
investigation of these pattern. The investigation of these patterns has
lead to many important finds.
The sceince of genetics began in 1900, when plant breeders
discovered the work o the Austrian monk Gregor Mendel, who was ignored in
1866. Mendel described the patterens of inheritance in different
pea-plant varieties. Mendel suggested each parent contributes only one
unit from each pair to its offspring. These units were later given the
name of genes.
Genes are carried by chromosomes, which led to intensive studies
of cell division. Offspring get a total of two traits. One of these is
dominant ond one is recessive. The dominant gene is the one that will
show up and the recessive is the one that is covered up by the dominant.
The recessive trait may show itself later on after being covered.
The ability of a person to produce pigment in hair, skin and eyes
depends on the presence of a particular allele. The lack of these alleles
is called albinism, which is caused by a different allele on the same
gene. The dominant gene is represented by a capital case letter, like "A"
for example. The recessive gene is represented by a lower case letter,
like "a" for example. Thus a heterozygous person (Aa) as well as a
homozygous dominant (AA) would have normal pigmentation if they had
albinism.
A cross of two heterozygous (Aa) would have a 1 in 4 chance of
being homozygous recessive (aa), and a 1 in 2 chance of being heterozygous
dominant (Aa). It isn't accurate to say that 25% of a family will have a
homozygous recessive or a heterozygous dominant disorder. The distinction
is made by physical features. These observable traits are called
phenotypes.
Method of solution
First we take a set population and factor in the defect Treacher
Collins. The we factor in the death rate of the human race. Next we
factor in emmigration and other forms of death such as war. Then we use
our formulas to calculate the amount of people with the defect, the people
with the dominant gene, the people recessive gene, and the people with the
actual defect.
Results
It takes five generations for two individuals to acquire the gene.
If you start with one couple after 60 years you get two people with the
gene out of 122 people. One has dominant and one has recessive. After 80
years you have 12 people with the gene out of 602 people. Seven have
dominant and five have recessive.
Conclusions
In conclusion it is a unique and uncommon defect in people. Though
uncommon the defect will show up in a population of 60 people. Where as
other defects tend to show up more often and have more serious effects.
Treacher Collins does not have as serious effects but is a defect people
tend to look in to curing.