Introduction to Genetics
A Curricular Unit
Developed by
P.J. Foley
Objectives
The learner will:
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Describe the experimental procedures that were used by Gregor Mendel.
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State and give an example of Mendel’s law of dominance and
his law of segregation.
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Explain Mendel’s law of segregation in terms of chromosomes and
meiosis.
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Define relevant terms to the study of genetics.
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Use Punnet squares to work out the possible results of various types
of genetic crosses.
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Research and gather information on topics related to field
of genetics.
Overview of Curricular Unit
The foundations for modern theories of genetics
and evolution were established in a single decade of the 19th century.
Between 1859 and 1869, Charles Darwin’s On the Origin of Species appeared,
Gregor Mendel discovered the basic laws of heredity and Johann Friedrich
Miescher found nucleic acids.
This curricular unit intends to present detailed
explanations of Mendel’s principles of heredity. His experiments
are described, and the laws of dominance and segregation are discussed.
The concept of the gene is related to Mendel’s “factor”.
Basic concepts and vocabulary in genetics
will be covered, including alleles, genotypes and phenotypes, probability,
the Punnett square, the law of independent assortment, and the dihybrid
cross.
Introduction
Genetics is the branch of biology that studies
the ways in which hereditary information is passed on from parents to offspring.
The first scientific study of heredity was carried out by Gregor Mendel
in the 1800s, before much was known about either chromosomes or cell division.
Assignment:
Research the following URLs on the background of the study of genetics
and Gregor Mendel. Your assignment will be to write a 500 word biography
on Gregor Mendel. Avoid going into depth on his work, try to stay
general in your descriptions. Please produce your document in MS
Word and email it to me as an attachment.
Assignment:
Review the following URL. Tomorrow, in class, we will be doing
the following lesson. Familiarize yourself with the short story and
be prepared to participate in the discussion.
Principles of Genetics
Pea plants were a good choice for Mendel's investigations.
They are easy to grow, and they mature quickly. Different plants
show sharply contrasting traits. For example, some are tall; some
are short. Some have green pods; some have yellow pods. Each
pair of traits is easily seen. In addition, the structure of the
pea flower and its natural method of pollination make it easy to use in
controlled experiments. Pea flowers normally self pollinate because
the stigma and anthers are enclosed by the petals. This reduces cross
pollination in nature. By removing the stamens before they ripened,
Mendel could prevent self pollination and cross pollinate the flower by
dusting pollen from another plant onto the stigma. If he wanted certain
plants to self pollinate in the normal way, he left them alone.
Assignment:
Read through the URL describing some of the terminology used in genetics.
At the end of the text, there is a lesson. Choose three partners
and work together to complete the lesson to gain a deeper understanding
of the terminology used in genetics. At the end of the week, there
will be a test on this unit. One section of the test will cover strictly
terminology. Use this lesson as a study tool for the test at the
end of the week.
Fundamentals of Genetics
During meiosis, alleles separate; they are
then paired with new homologous chromosomes at fertilization, producing
heterozygous and homozygous combinations. The concepts of probability
and the Punnet square are useful in understanding the possible results
of various genetic crosses.
Assignment:
Look up the following URLs. On each of these sites, there are
either virtual labs, practice sets or tutorials modeling the fundamentals
of genetics. Familiarize yourself with the concepts of probability
and the Punnet square while practicing on these sites.
Other Concepts in Genetics
Evolution itself begins with genetic change.
This change can be the result of a mutation in chromosomes or genes.
It may occur during the processes of gametogenesis or fertilization.
Any of these changes can cause variation in the next generation.
When the variation benefits the organism, it will become more and more
prevalent in future generations. Eventually, the genetic change may
become part of a mainstream population.
Current advances in molecular biology and genetics
have been occurring at an unprecedented rate. The newest techniques
allow geneticists to study genes right down to the molecular level.
Mutations in specific genes or chromosomes can be viewed and understood
more precisely. The results of these studies, the growing technology
around them, and the potential for understanding and influencing genetic
situations border on revolutionary.
Assignment:
Your assignment will be to write a research paper on a relevant topic
related to genetics. Below is a "for starters..." list of URLs that
you can use to start your research. Some of the relevant topics may
include: genetic disorders, genetic engineering, the issue of cloning,
genetic counseling, how genetics influences evolution, neurological genetic
disorders, or the Human Genome Project. Your research paper must
be 5-7 pages in length and include at least 10 cited sources. Please
produce your paper in MS Word and email to me as an attachment.
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