a) Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.
b) How did Sturtevant explain gene mapping while working with Morgan?

Solution

a) Drosophila melanogaster :

Morgan carried out several dihybrid crosses in Drosophila to study gens that were sex-lined.

Morgan and his group knew that the genes were located on the X chromosome and saw quickly that when the two genes in a dihybrid cross were situated on the same chromosome, the proportion of parental gene combinations were much higher than the non-parental type. Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage to describe this physical association of genes on a chromosome and the term recombination to describe the generation of non-parental gene combination. Morgan and his group also found that even when genes were grouped on the same chromosome, some genes were very tightly linked (showed very low recombination) while others were loosely linked.

b) Morgans student Alfred Sturtevant used the frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes and ‘mapped’ their position on the chromosome. Today genetic maps are extensively used as a starting point in the sequencing of whole genomes.

Some More Questions From Principles of Inheritance and Variation Chapter

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Principles Of Inheritance And Variation

a) Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.
b) How did Sturtevant explain gene mapping while working with Morgan?

Some More Questions From Principles of Inheritance and Variation Chapter

Write down Mendel’s dihybrid Phenotypic ratio

Who were the rediscoverers of Mendelism ?

What are the real determinants of what an organism will become ?

What is the unique feature of F1 generation ?

What will be the genetic make up of an organism which suffers from sickle cell anaemia ?

What do the symbols square and circle in a pedigree chart indicate ?

Define heterogamy. Give an example.

How many chromosomes are found in human cells ?

Why is male Drosophila regarded as heterogametic ?

What term is used for the two chromatids resulting from the interchange of segments during crossing over ?

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Principles Of Inheritance And Variation

a) Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.b) How did Sturtevant explain gene mapping while working with Morgan?

Some More Questions From Principles of Inheritance and Variation Chapter

Write down Mendel’s dihybrid Phenotypic ratio

Who were the rediscoverers of Mendelism ?

What are the real determinants of what an organism will become ?

What is the unique feature of F1 generation ?

What will be the genetic make up of an organism which suffers from sickle cell anaemia ?

What do the symbols square and circle in a pedigree chart indicate ?

Define heterogamy. Give an example.

How many chromosomes are found in human cells ?

Why is male Drosophila regarded as heterogametic ?

What term is used for the two chromatids resulting from the interchange of segments during crossing over ?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

a) Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.
b) How did Sturtevant explain gene mapping while working with Morgan?