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Single-gene inheritance - Single-gene inheritance patterns

16 important questions on Single-gene inheritance - Single-gene inheritance patterns

The genetic approach to understanding any biological property is to find the subset of genes in the genome that influence that property, a process sometimes referred to as ...

Gene discovery

Are there several different types of analytical approaches to gene discovery?

Yes, but one widely used method relies on the detection of single-gene inheritance patterns, which is what we are going to be looking at

Are all of genetics, in one aspect or another, based on heritable variants?

Yes

What is, in genetics, the most common form of any property of an organism called?

The wild-type

What are the heritable variants observed in an organism that differs from the wild type called?

Mutants (individual organisms having some sort of abnormal property)

What are the alternative forms of the property called?

Phenotypes

Do mutants arise from wild types by a process called mutation, which results in a heritable change in the DNA of a gene?

Yes, the changed form of the gene is also called a mutation. Mutations are not always detrimental to an organism; sometimes they can be advantageous, but most often they have no observable effect. Generally it can be said that mutations arise from mistakes in cellular processing of DNA.

Do most natural populations also show polymorphisms (the coexistence of two or more reasonably common phenotypes of a biological property)?

Yes

Can (and does) genetic analysis use polymorphisms? Are mutants more useful?

Yes, but polymorphisms have the disadvantage that they generally do not involve the specific property of interest to the researcher. Mutants are much more useful because they allow the researcher to zero in on any property.

What are the general steps of functional analysis by gene discovery?

Amass mutants affecting the biological property of interest.
Cross (mate) the mutants to wild type to see if their descendants show ratios of wild to mutant that are characteristic of single-gene inheritance.
Deduce the functions of the gene at the molecular level.
Deduce how the gene interacts with other genes to produce the property in question.

Even though mutants are individually rare, there are ways of enhancing their recovery. What is one widely used method?

To treat the organism with radiation or chemicals that increase the mutation rate.
After treatment, the most direct way to identify mutants is to visually screen a very large number of individuals, looking for a chance occurrence of mutants in that population. Also, various selection methods can be devised to enrich for the types sought.

Armed with a set of mutants affecting the property of interest, one hopes that each mutant represents a lesion in one of a set of genes that control the property. Hence, the hope is that a reasonably complete gene pathway or network is represented. Are all mutants caused by lesions within one gene?

No, some have far more complex determination, so first each mutant has to be tested to see if indeed it is caused by a single-gene mutation.

What is the test for single-gene inheritance?

To mate individuals showing the mutant property with wild-type and then analyze the first and second generation of descendants.

After a set of key genes has been defined through genetic dissection, several different molecular methods can be used to establish the functions of each of the genes. What is this type of approach to gene discovery sometimes called?

Forward genetics, a strategy to understanding biological function starting with random single-gene mutants and ending with their DNA sequence and biochemical function.

Gene discovery is important not only in experimental organisms but also in applied studies. Which two crucial areas is gene discovery used in?

Agriculture, where gene discovery can be used to understand a desirable commercial property of an organism, such as its protein content.
Human genetics: to know which gene functions are involved in a specific disease or condition is useful information in finding therapies.

Was Mendel the first person to discover any gene?

Yes

The question on the page originate from the summary of the following study material:

An Introduction to Genetic Analysis | 9781319114770 | Anthony J F Griffiths, et al

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