18 Questions
What is the term for the phenomenon where a single gene has multiple phenotypic effects?
Pleiotropy
Which of the following determines the child's sex?
Father's Y chromosome
What is the term for the interaction between genes at two different loci that influences the expression of a trait?
Epistasis
In the example of Labrador retrievers, how many genes determine the coat color?
Two
What is the term for the phenomenon where multiple genes influence a single trait?
Polygenic inheritance
In the example of cystic fibrosis and sickle-cell disease, what is the genetic concept that is responsible for the multiple symptoms?
Pleiotropy
What is the term for the phenomenon where one gene affects the expression of another gene?
Epistasis
What is the underlying mechanism of polygenic inheritance?
An additive effect of two or more genes on a single phenotype
What is the main difference between continuous and discontinuous variation?
The number of genes involved in the variation
What is the characteristic of quantitative characters in a population?
They vary in a continuous manner
In a genetic cross, what is the term for the ratio of phenotypes observed in the offspring?
Phenotypic ratio
What is the term used to describe traits that depend on multiple genes combined with environmental influences?
Multifactorial
What is the term for the interaction between two or more genes that affect a single phenotypic character?
Polygenic inheritance
What is the purpose of the chi-squared (χ2) test in genetics?
To test the significance of the difference between observed and expected results
What is the relationship between the number of dark-skin alleles and the phenotype of skin color in humans?
More dark-skin alleles result in darker skin color
What is the term for the phenomenon where a single gene affects multiple phenotypic characters?
Pleiotropy
What is the result of the additive effect of multiple genes on a single phenotype?
Quantitative variation
Which of the following is an example of polygenic inheritance?
Skin color
Study Notes
Polygenic Inheritance
- Polygenic inheritance occurs when two or more genes affect a single phenotype, resulting in quantitative variation.
- Quantitative characters vary in the population along a continuum, and skin color in humans is an example of polygenic inheritance.
Nature and Nurture
- Traits that depend on multiple genes combined with environmental influences are called multifactorial.
- The phenotypic range is broadest for polygenic characters, which can be influenced by both genetic and environmental factors.
Other Genetic Concepts
Pleiotropy
- Pleiotropy is when a single gene has multiple phenotypic effects, such as in certain hereditary diseases like cystic fibrosis and sickle-cell disease.
Linkage
- Linkage refers to the pairing of genes during meiosis, where genes that are close together on the same chromosome tend to be inherited together.
Epistasis
- Epistasis occurs when a gene at one locus alters the phenotypic expression of a gene at a second locus, such as in the determination of coat color in Labrador retrievers.
- Epistasis can affect the expression of multiple genes and result in complex phenotypes.
Multiple Alleles
- Multiple alleles refer to the presence of more than two alleles for a particular gene, such as the ABO blood group alleles.
- One gene can affect multiple phenotypic characters, such as sickle-cell disease.
Meiosis and Genetics
- Meiosis is a process that can lead to variation through the independent assortment of alleles.
- Genetic diagrams can be used to solve problems involving sex linkage and codominance.
- Epistasis can be predicted using genetic diagrams and the chi-squared (χ2) test can be used to test the significance of the difference between observed and expected results.
Variation
- Continuous variation occurs when multiple genes influence a trait, resulting in a range of phenotypes.
- Discontinuous variation occurs when a single gene or a few genes influence a trait, resulting in distinct phenotypes.
- Both genotype and environment contribute to phenotypic variation.
Test your knowledge of genetics concepts, including pleiotropy, linkage, epistasis, and polygenic inheritance. Learn how these concepts relate to hereditary diseases and sex determination. Assess your understanding of multiple alleles and their effects on an organism's phenotype.
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