Question Video: Identifying a Duplication Mutation | Nagwa Question Video: Identifying a Duplication Mutation | Nagwa

Question Video: Identifying a Duplication Mutation Biology • Third Year of Secondary School

The diagram shows a simplified outline of the different types of chromosomal mutations that can occur. Which diagram (1, 2, or 3) demonstrates a duplication mutation?

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Video Transcript

The diagram provided shows a simplified outline of the different types of chromosomal mutations that can occur. Which diagram — 1, 2, or 3 — demonstrates a duplication mutation?

This question requires us to identify a duplication mutation on chromosomes. You might recall that a mutation refers to a change in the DNA sequence. Mutations can occur in a single nucleotide of a DNA sequence or can occur over a larger area and affect chromosomes. Most of our cells contain DNA packaged into structures called chromosomes. We have 23 pairs of chromosomes, or 46 chromosomes in total. And we get one copy from our biological mother and the other from our biological father.

In our provided diagram, we see one pair of a specific chromosome that’s indicated here. Notice the different bands on each chromosome. These simply represent different sections of DNA that can contain numerous genes. They are the same between the chromosomes because these two chromosomes are nearly identical. We can follow how these bands change position to illustrate the different kinds of chromosomal mutations that can occur. You can see the different mutations below, and all we have to do is label them with their type.

One type of chromosome mutation is called a deletion. You can see the blue and gray bands are missing in one copy of the chromosome. Here, a number of genes would be deleted, which would likely have serious consequences.

The next example is called an inversion mutation. This occurs when a portion of a chromosome is flipped or inverted. So the genes on this chromosome may not appear in the order we would expect. You can see the gray and blue bands inverted in the diagram. This type of mutation can sometimes lead to problems with fertility.

Finally, a duplication mutation occurs when a segment of a chromosome is copied. You can see the red and orange bands are duplicated in one of the chromosome copies. This results in a duplication of the genes as well, which can also lead to problems.

So the diagram that demonstrates a duplication mutation is given by mutation 3.

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