Chapter 12
Classical and Modern Genetics
![Genetic Lingo](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10771.jpg)
An organism is diploid if it inherits two variants, or alleles, of each gene, one from each parent. These two alleles constitute the genotype for a…
![Punnett Squares](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10772.jpg)
A Punnett square displays the possible genotypes offspring can inherit from two parental genotypes. If a trait’s inheritance pattern (e.g.,…
![Dihybrid Crosses](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10774.jpg)
To determine whether traits are inherited together or separately, Gregor Mendel crossed pea plants that differed in two traits. These parental…
![Law of Segregation](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10978.jpg)
When crossing pea plants, Mendel noticed that one of the parental traits would sometimes disappear in the first generation of offspring, called the…
![Test Cross](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/11012.jpg)
Alleles are different forms of the same gene. Humans and other diploid organisms inherit two alleles of every gene, one from each parent.
An allele…
![Pedigree Analysis](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10775.jpg)
A pedigree is a diagram displaying a family’s history of a trait. Analyzing pedigrees can reveal (1) whether a trait is dominant or…
![Multiple Allele Traits](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10777.jpg)
Multiple allelism describes genes that exist in three or more allelic forms. Although diploid organisms, like humans, normally possess only two…
![Chromosomal Theory of Inheritance](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/11010.jpg)
In 1866, Gregor Mendel published the results of his pea plant breeding experiments, providing evidence for predictable patterns in the inheritance of…
![X-linked Traits](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10980.jpg)
In most mammalian species, females have two X sex chromosomes and males have an X and Y. As a result, mutations on the X chromosome in females may be…
![Sex-linked Disorders](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10981.jpg)
Like autosomes, sex chromosomes contain a variety of genes necessary for normal body function. When a mutation in one of these genes results in…
![Epistasis](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10779.jpg)
In addition to multiple alleles at the same locus influencing traits, numerous genes or alleles at different locations may interact and influence…
![Polygenic Traits](https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10778.jpg)
When more than one gene is responsible for a given phenotype, the trait is considered polygenic. Human height is a polygenic trait. Studies have…
![High-Throughput Robotically Assisted Isolation of Temperature-sensitive Lethal Mutants in <em>Chlamydomonas reinhardtii</em>](https://cloudfront.jove.com/files/thumbs/54831_t.png)
High-Throughput Robotically Assisted Isolation of Temperature-sensitive Lethal Mutants in Chlamydomonas reinhardtii
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Systematic identification and characterization of genetic perturbations have proven useful to decipher gene function and cellular pathways. However,…
![Optogenetic Random Mutagenesis Using Histone-miniSOG in <em>C. elegans</em>](https://cloudfront.jove.com/files/thumbs/54810_t.png)
Forward genetic screening in model organisms is the workhorse to discover functionally important genes and pathways in many biological processes. In…