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Chapter 25: Problem 10

List as many human traits as you can that are likely to be under the control of a polvaenic mode of inheritance

Short Answer

Expert verified
Answer: Polygenic inheritance is a type of inheritance where multiple genes influence a particular trait, leading to a wide range of phenotypes. Some human traits likely to be under polygenic inheritance include skin color, height, intelligence, hair color, eye color, body mass index (BMI), and susceptibility to certain diseases such as diabetes, hypertension, and heart disease.

Step by step solution

01

Define polygenic inheritance

Polygenic inheritance is a type of inheritance where multiple genes influence a particular trait. This results in a range of phenotypes, as each gene may have various alleles, leading to a wide variety of combinations which contribute to the trait.
02

Identify traits with multiple phenotypes

To list human traits that are likely to be under polygenic inheritance, consider traits that display a wide range of phenotypes. This is often an indication that there are multiple genes at work.
03

List human traits with polygenic inheritance

Below are some human traits that are widely believed to be under polygenic inheritance: 1. Skin color: The color of one's skin is determined by the genes controlling the production and distribution of melanin, and multiple genes contribute to this trait, resulting in various shades of skin color. 2. Height: Human height is a complex trait influenced by several genes, as well as environmental factors like nutrition. 3. Intelligence: While still debated, it is believed that intelligence is influenced by multiple genes. It is a complex trait with a wide variation observed in the population. 4. Hair color: Hair color is determined by multiple genes that control the production and distribution of pigments, which results in different shades and hues of hair color. 5. Eye color: Eye color is determined by multiple genes that control the production and distribution of pigments, which results in different shades and hues of eye color. 6. Body mass index (BMI): BMI is influenced by multiple genes, in addition to lifestyle and environmental factors. 7. Susceptibility to certain diseases: Many diseases, such as diabetes, hypertension, and heart disease, are influenced by a combination of several genes and environmental factors. These are just a few examples of human traits likely to be under the control of a polygenic mode of inheritance. There are many other traits that exhibit wide variation in the population, and as our understanding of genetics continues to grow, it is likely that more examples will be identified in the future.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Understanding Human Genetics
When we dive into the study of human genetics, we're looking at how inherited characteristics are passed down through generations. Human genetics is a branch of biology concerned with the study of genes, genetic variation, and heredity, especially as it applies to humans.

Each person's DNA contains genes that are the basic units of heredity, determining much of our physical traits and potentially influencing our behavior and disease risk. Since humans have approximately 20,000-25,000 genes, there's a rich tapestry of information leading to varied expressions of traits.

Polygenic Inheritance in Human Genetics

Polygenic inheritance is especially significant because unlike single-gene traits, it involves multiple genes, each contributing a small effect to the outcome. Think of it as a team sport where each player (gene) contributes to the final score (trait), whether it's your height, skin tone, or risk for certain illnesses. Unlike monogenic traits, which are determined by a single gene, polygenic traits don't follow simple Mendelian inheritance patterns. That's why siblings can have wide variations in their phenotypes for the same polygenic trait.
Phenotypic Variation
The range of differences in physical and physiological traits among individuals of the same species is known as phenotypic variation. It is the outward expression of an organism's genetic code, combined with the influence of environmental factors.

For instance, height in humans can vary greatly even within a family, and it's a classic example of a polygenic trait. Having numerous contributing genes allows for a gradient of possible heights rather than distinct categories. Environment also plays a pivotal role; adequate nutrition during childhood can influence someone's adult height regardless of genetics.In other words, unlike Mendelian traits that offer limited outcomes, polygenic traits showcase a spectrum of possibilities. This is why, sometimes, children may resemble a grandparent or even a more distant ancestor, embodying a recombination of traits across the family tree.
Genetic Traits
Genetic traits are characteristics that are inherited from our parents through our genes. They can be as visible as eye color, or as complex as susceptibility to diseases. In polygenic inheritance, several genes contribute to a single trait, adding layers of complexity to how these characteristics are expressed.

As researchers delve deeper into human genetics, they're discovering that even traits once thought to be controlled by a single gene, like eye color, are influenced by several genes. This means that predicting traits based on genetics alone can be challenging, and understanding the underlying genetics is essential for grasping concepts like polygenic inheritance.Moreover, while we often think of genetic traits as fixed, some can change over time due to environmental pressures or lifestyle choices. This intertwining of nature (genes) and nurture (environment) underscores the fascinating dynamic of human genetics.

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Most popular questions from this chapter

Type A1B brachydactyly (short middle phalanges) is a genetically determined trait that maps to the short arm of chromosome 5 in humans. If you classify individuals as either having or not having brachydactyly, the trait appears to follow a singlelocus, incompletely dominant pattern of inheritance. However, If one examines the fingers and toes of affected individuals, one sees a range of expression from extremely short to only slightly short. What might cause such variation in the expression of brachydactyly?

Students in a genetics laboratory began an experiment in an attempt to increase heat tolerance in two strains of Drosophila melanogaster, One strain was trapped from the wild six weeks before the experiment was to begin; the other was obtained from a Drosophila repository at a university laboratory, In which strain would you expect to see the most rapid and extensive response to heat-tolerance selection, and why?

In a series of crosses between two true-breeding strains of peaches, the \(F_{1}\) generation was uniform, producing 30 -g peaches. The \(F_{2}\) fruit mass ranges from 38 to 22 g at intervals of 2 g. (a) Using these data, determine the number of polygenic loci involved in the inheritance of peach mass. (b) Using gene symbols of your choice, give the genotypes of the parents and the \(F_{1}\)

In a herd of dairy cows the narrow-sense heritability for milk protein content is \(0.76,\) and for milk butterfat it is \(0.82 .\) The cor relation coefficient between milk protein content and butterfat is \(0.91 .\) If the farmer selects for cows producing more butterfat in their milk, what will be the most likely effect on milk protein content in the next generation?

Height in humans depends on the additive action of genes. Assume that this trait is controlled by the four loci \(R, S, T,\) and \(U\) and that environmental effects are negligible. Instead of additive versus nonadditive alleles, assume that additive and partially additive alleles exist. Additive alleles contribute two units, and partially additive alleles contribute one unit to height. (a) Can two individuals of moderate height produce offspring that are much taller or shorter than either parent? If so, how? (b) If an individual with the minimum height specified by these genes marries an individual of intermediate or moderate height, will any of their children be taller than the tall parent? Why or why not?
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