13 terms

Genetics- Chromosome Theory

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Explain the chromosomal theory of inheritance.
The chromosomal theory of inheritance holds that the separation of maternal and paternal chromosomes during gamete formation is the physical basis of Mendelian inheritance.
Describe the historical context of the development of the chromosomal theory of inheritance.
When Gregor Mendel first presented his principles of segregation and independent assortment, no one recognized his work's significance. Almost 40 years later, Walter Sutton observed grasshopper cells undergoing meiosis and formulated the chromosomal theory of inheritance.
Explain how Thomas Morgan's work contributed to the scientific understanding of heredity.
Thomas Morgan expanded Mendel's principles through his studies of Drosophila (fruit flies). He hypothesized that a mutation expressed predominantly in males must be carried on the X chromosome. In females heterozygous for the mutation, a second X chromosome masks the mutation. Morgan realized that, contrary to Mendel's principle of independent assortment, some alleles do not segregate independently. Alleles that are located near each other on the same chromosome are likely to be inherited together, because entire chromosomes are separated into gametes during meiosis.
Provide an example of an inheritance pattern that cannot be explained by simple Mendelian genetics.
Examples of inheritance patterns that cannot be explained by simple Mendelian genetics are sex-linked traits such as those for red-green color blindness, the progressive muscular disorder, Duchenne muscular dystrophy, and hemophilia, a disorder that impairs blood clotting.
Describe the cellular process of how genetic information passes from generation to generation.
Genetic information passes from generation to generation through the formation of gametes. Different alleles for the same trait are located on different chromosomes within a pair. During gamete formation, chromosomes independently segregate.
Explain why early research in genetics is important for scientific advancement today.
Early research in genetics established fruit flies as an important model organism that is still used today. In addition, early research in genetics determined the principles of segregation and independent assortment, which are used as the foundation for disease- and treatment-focused research.
Alfred Sturtevant
Scientist who developed the first genetic map showing the locations of specific genes.
chromosome theory of inheritance
The theory that chromosomes are the basis of all genetic inheritance.
linked gene
A gene that is co-transcribed with another, due to proximity on the same chromosome.
mutant
Variations on the wild-type phenotype caused by mutations or changes in the genetic makeup.
sex linkage
Genes associated with the sex chromosomes.
sex-linked disorder
A disorder arising from dysfunction in a sex chromosome or associated strongly with characteristics determined by sex chromosomes.
wild type
Most common phenotype in nature.