by Professor Kate Lormand, M.S.
Have you ever wondered where you your physical traits came from? Maybe someone has exclaimed “you look just like Uncle Horatio”……and you are a girl! From the beginnings of time man has had a basic understanding of the concept behind genetics as is evident from the domestication of plants and animals. As man observed traits that were desirable in plants and animals he would selectively breed for those traits.
The cultivation of corn (maize) is a perfect example of this. Corn as we know it today began as a small plant known as teosinte.
It is hypothesized that a plant with unusually large ears was collected and those seeds were saved and replanted then the next generation's large ears were saved and so to arrive at the sized ear of corn that is typical today. This process began about 8,000 years ago in Mesoamerica.
In the late 1800's Gregor Mendel, the “father” of genetics, began his experiments with sweet peas. He generally understood that traits could be passed from one generation to the next, but he had no idea of how this actually happened. Mendel's investigations showed that “units of heredity” as he called them would separate as each parent went through the process of forming sex cells. These “units” would then recombine in the offspring thus passing the unit of heredity from the parent to the child.
Today we know these units of heredity as the genes which are located on the chromosomes. Each person has 46 chromosomes organized in pairs, thus creating 23 pairs of chromosomes. When egg and sperm cells are created they go through a process known as meiosis which functions to separate the pairs of chromosomes. As a result each egg or sperm produced has 23 individual chromosomes. When a sperm and egg unite the zygote (fertilized egg) again has 46 chromosomes arranged in 23 pairs.
Each gene carries the information for the making of a protein and can exist in two forms, either it can make the protein or it cannot make it. There are exceptions to this basic rule of genetics, but they are beyond the scope of this discussion. The alternate forms of a gene are called alleles. The genes from the mother and the father for a particular trait carry the same basic information, but they can vary in whether the protein is made or not.
Consider the gene for freckles. In genetics a capital letter is used to indicate a dominant or protein making allele's trait and a lower case letter represent a recessive situation or the non protein making allele. Thus, a homozygous dominant condition for freckles would be FF and a homozygous recessive condition would be ff. If there is a mix of the two forms of the alleles it is heterozygous Ff. A heterozygous situation in many genes will result in the dominant condition being presented. When discussing the information on the gene it is referred to as a genotype, so Ff is a genotype and what it looks like in a person is the phenotype, so Ff results in freckles.
Using this basic overview of genetics students can perform a fun activity, and by using some rather unappealing traits, they can create a hypothetical child. Not only will they see how traits are passed from the parent to the child, they will also see just how random the process is. After the activity is completed, the students should draw a picture of the resulting child. This activity can be repeated over and over again and each repetition should produce different results.
Who Did I Get This Nose From - Activity Materials_pdf
Kate Lormand, M.S. has been an adjunct biology professor for over 20 years and teaches online as well as face-to-face courses. Her Masters Degree is in Plant Genetics and Agriculture. Kate has three sons, and her family spends a great deal of time gardening and attending swim meets.
Kate also works with Hands-On- Labs, Inc. ( www.LabPaq.com ) as a biology researcher to develop safe yet effective laboratory experiments for inclusion in LabPaqs. Hands-On Labs, an educator owned company, pioneered the development of LabPaqs for home-based experimentation. LabPaqs are academically aligned collections of science equipment and supplies that allow students to perform traditional science experimentation at home. Various LabPaqs in biology, chemistry, geology, and physics are used by thousands of online and alternative high school and college students each year. To learn more about the college, high school, and AP-level high school LabPaqs available for home instruction, visit www.LabPaq.com .
Have you ever wondered where you your physical traits came from? Maybe someone has exclaimed “you look just like Uncle Horatio”……and you are a girl! From the beginnings of time man has had a basic understanding of the concept behind genetics as is evident from the domestication of plants and animals. As man observed traits that were desirable in plants and animals he would selectively breed for those traits.
The cultivation of corn (maize) is a perfect example of this. Corn as we know it today began as a small plant known as teosinte.
It is hypothesized that a plant with unusually large ears was collected and those seeds were saved and replanted then the next generation's large ears were saved and so to arrive at the sized ear of corn that is typical today. This process began about 8,000 years ago in Mesoamerica.
In the late 1800's Gregor Mendel, the “father” of genetics, began his experiments with sweet peas. He generally understood that traits could be passed from one generation to the next, but he had no idea of how this actually happened. Mendel's investigations showed that “units of heredity” as he called them would separate as each parent went through the process of forming sex cells. These “units” would then recombine in the offspring thus passing the unit of heredity from the parent to the child.
Today we know these units of heredity as the genes which are located on the chromosomes. Each person has 46 chromosomes organized in pairs, thus creating 23 pairs of chromosomes. When egg and sperm cells are created they go through a process known as meiosis which functions to separate the pairs of chromosomes. As a result each egg or sperm produced has 23 individual chromosomes. When a sperm and egg unite the zygote (fertilized egg) again has 46 chromosomes arranged in 23 pairs.
Each gene carries the information for the making of a protein and can exist in two forms, either it can make the protein or it cannot make it. There are exceptions to this basic rule of genetics, but they are beyond the scope of this discussion. The alternate forms of a gene are called alleles. The genes from the mother and the father for a particular trait carry the same basic information, but they can vary in whether the protein is made or not.
Consider the gene for freckles. In genetics a capital letter is used to indicate a dominant or protein making allele's trait and a lower case letter represent a recessive situation or the non protein making allele. Thus, a homozygous dominant condition for freckles would be FF and a homozygous recessive condition would be ff. If there is a mix of the two forms of the alleles it is heterozygous Ff. A heterozygous situation in many genes will result in the dominant condition being presented. When discussing the information on the gene it is referred to as a genotype, so Ff is a genotype and what it looks like in a person is the phenotype, so Ff results in freckles.
Using this basic overview of genetics students can perform a fun activity, and by using some rather unappealing traits, they can create a hypothetical child. Not only will they see how traits are passed from the parent to the child, they will also see just how random the process is. After the activity is completed, the students should draw a picture of the resulting child. This activity can be repeated over and over again and each repetition should produce different results.
Who Did I Get This Nose From - Activity Materials_pdf
Kate Lormand, M.S. has been an adjunct biology professor for over 20 years and teaches online as well as face-to-face courses. Her Masters Degree is in Plant Genetics and Agriculture. Kate has three sons, and her family spends a great deal of time gardening and attending swim meets.
Kate also works with Hands-On- Labs, Inc. ( www.LabPaq.com ) as a biology researcher to develop safe yet effective laboratory experiments for inclusion in LabPaqs. Hands-On Labs, an educator owned company, pioneered the development of LabPaqs for home-based experimentation. LabPaqs are academically aligned collections of science equipment and supplies that allow students to perform traditional science experimentation at home. Various LabPaqs in biology, chemistry, geology, and physics are used by thousands of online and alternative high school and college students each year. To learn more about the college, high school, and AP-level high school LabPaqs available for home instruction, visit www.LabPaq.com .
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