🧬Biocode Explorer - Gene Mapping

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Linkage

Thomas Hunt Morgan

The concept of linkage in genetics was discovered and initially described by Thomas Hunt Morgan and his colleagues in the early 20th century. Morgan, an American geneticist, conducted pioneering research using the fruit fly Drosophila melanogaster. Through his experiments, Morgan observed that certain traits, such as eye color and wing shape, tended to be inherited together more frequently than expected based on Mendelian principles of independent assortment.

Morgan proposes that genes located on the same chromosome tend to be inherited together due to their physical proximity. This discovery revolutionized the understanding of genetics by demonstrating that genes are arranged in a linear order on chromosomes and provided a foundation for later studies in gene mapping, genetic recombination, and chromosome structure.

For his work on genetics, including the discovery of linkage, Morgan was awarded the Nobel Prize in Physiology or Medicine in 1933 [Reference]. His research laid the groundwork for the field of cytogenetics and significantly contributed to the modern understanding of inheritance and genetic variability.[Reference]

In the present chapter, we will study some key concepts in genetics that explain how traits are passed on and how variations arise.

First, we will learn about crossing over, a process that occurs during meiosis where homologous chromosomes exchange genetic material. This process is important because it increases genetic variation in offspring. Next, we will explore linkage, which refers to genes that are located close to each other on the same chromosome and tend to be inherited together. Understanding linkage is important because it helps explain why some traits do not follow Mendel’s expected ratios. Finally, we will discuss recombination frequency, which measures how often crossing over occurs between two genes. This concept is widely used to create genetic maps and determine the distance between genes on a chromosome. By the end of this chapter, you will have a clear understanding of crossing over, linkage, and recombination frequency, and their role in heredity and genetic diversity.