Lab Report Zea Mays
Report 1: Genetics-411 Population Genetics of Albinism in Zea mays
Spring 2013
2/16/2013
Tory Thomason
Introduction Zea mays or maize was chosen as the study system for this experiment for many reasons. The phenotype being studied is observable to the naked eye, green or yellow plants. It is an important agricultural system used in crop and is an ideal genetic model. Zea mays also has a quick turnaround time from generation to generation and crossing Zea mays was feasible in the facility. Lethal alleles are those that fail to successfully code for the proper production of a functional protein that is vital for life. Recessive lethal alleles are mutations that are only lethal to homozygotic individuals with two copies of the mutated allele (Castle, 1910) . In humans cystic fibrosis and sickle cell anemia are two examples of recessive lethal alleles. A dominant lethal allele is a mutation that is lethal to any individual that has one or two copies of the allele. Huntington’s disease is an example of a dominant lethal allele, it is maintained in the population because of the late onset of death. Sub lethal alleles are those that cause death in only some carriers of the gene, an example of this is hemophilia where the male who has an affected X chromosome, will only die if he is affected by trauma to the body, otherwise he will stay healthy. Zea mays has a lethal recessive allele for albinism; which in homozygotes causes a plant to grow with zero chlorophyll and to undergo death very fast. Heterozygotes are the carriers for this trait since the recessive homozygotes are killed. The heterozygotes for the “L” allele are green since they produce chlorophyll.
The aim of the Zea mays investigation was to distinguish lethal alleles by reviewing observing frequencies in growth. In order to do this, dominant and recessive alleles had to be observed. In Zea mays deleterious alleles cause a loss of function through the
Spring 2013
2/16/2013
Tory Thomason
Introduction Zea mays or maize was chosen as the study system for this experiment for many reasons. The phenotype being studied is observable to the naked eye, green or yellow plants. It is an important agricultural system used in crop and is an ideal genetic model. Zea mays also has a quick turnaround time from generation to generation and crossing Zea mays was feasible in the facility. Lethal alleles are those that fail to successfully code for the proper production of a functional protein that is vital for life. Recessive lethal alleles are mutations that are only lethal to homozygotic individuals with two copies of the mutated allele (Castle, 1910) . In humans cystic fibrosis and sickle cell anemia are two examples of recessive lethal alleles. A dominant lethal allele is a mutation that is lethal to any individual that has one or two copies of the allele. Huntington’s disease is an example of a dominant lethal allele, it is maintained in the population because of the late onset of death. Sub lethal alleles are those that cause death in only some carriers of the gene, an example of this is hemophilia where the male who has an affected X chromosome, will only die if he is affected by trauma to the body, otherwise he will stay healthy. Zea mays has a lethal recessive allele for albinism; which in homozygotes causes a plant to grow with zero chlorophyll and to undergo death very fast. Heterozygotes are the carriers for this trait since the recessive homozygotes are killed. The heterozygotes for the “L” allele are green since they produce chlorophyll.
The aim of the Zea mays investigation was to distinguish lethal alleles by reviewing observing frequencies in growth. In order to do this, dominant and recessive alleles had to be observed. In Zea mays deleterious alleles cause a loss of function through the
Cited: Castle, L., 1910. On a Modified Mendelian Ratio Among Yellow Mice. Science, pp. 868-870. McCune, 2004. Two classes of deleterious recessive alleles in a Natural Population of Zebrafish. The Royal Society, pp. 2025-2033. Salerno, J. C., 2007. Genetics and statistical association between lethal alleles and quantitative yield factors in maize (zea mays). Journal of Basic and Applied Genetics, pp. 7-13. Sunyaev, 2000. SNP frequencies in human genes: an excess of rare alleles and differing modes of selection. Trends in Genetics, pp. 335-337.