Chromosomal Aberrations | Deletion | Duplication | Inversion | Translocation

Summary

The video explains chromosomal aberrations, which refer to abnormalities in chromosome number or structure. It covers four types: deletion, duplication, inversion, and translocation. Deletion involves the loss of a chromosome segment, while duplication is when a segment is repeated. Inversion occurs when the order of genes is reversed, and translocation involves the exchange of chromosomal segments, often between non-homologous chromosomes. These abnormalities play crucial roles in evolution, species differentiation, and can lead to various disorders. Examples in organisms like Drosophila, maize, and humans are highlighted to illustrate each type.

Takeaways

• 😀 Chromosomal aberrations are abnormalities in chromosome number or structure that deviate from the diploid set.
• 😀 Chromosomal aberrations are categorized into four types: deletion, duplication, inversion, and translocation.
• 😀 Deletion refers to the loss of a segment of genetic material in a chromosome. It can be terminal (near the end) or intercalary (in the middle).
• 😀 Terminal deletions occur near the chromosome end and are seen in organisms like Drosophila and maize.
• 😀 Intercalary deletions happen in the middle of a chromosome and are also observed in species like Drosophila.
• 😀 Most chromosomal deletions result in the death of the organism.
• 😀 Duplication is when a chromosome segment appears more than once in a chromosome. It can contribute to evolutionary changes.
• 😀 Inversion is when the order of genes in a chromosome is reversed by 180 degrees. There are two types: pericentric and paracentric inversion.
• 😀 Pericentric inversion involves the inversion of a chromosome segment that contains the centromere, and it can influence evolution.
• 😀 Translocation is the exchange of chromosome segments between non-homologous chromosomes. It can be reciprocal or non-reciprocal.
• 😀 Heterozygous translocation occurs when one chromosome is normal and the other has an interchange of segments, whereas homozygous translocation involves both chromosomes having translocated segments.

Q & A

What are chromosomal aberrations?

Chromosomal aberrations refer to visible abnormalities in chromosome number or structure, deviating from the typical diploid set of chromosomes in an organism.

What are the main types of chromosomal aberrations?

Chromosomal aberrations are divided into four main types: deletion, duplication, inversion, and translocation.

What is a chromosomal deletion?

A chromosomal deletion occurs when a segment of genetic material is lost from a chromosome. It can be terminal (near the end of the chromosome) or intercalary (in the middle of the chromosome).

Can you give examples of organisms affected by chromosomal deletion?

Examples of organisms affected by chromosomal deletion include Drosophila and maize.

What is chromosomal duplication?

Chromosomal duplication happens when a segment of a chromosome is present more than once. This results in repeated genetic material, which can sometimes be beneficial for the evolution of an organism.

What is an example of gene duplication?

An example of gene duplication is when the gene order in a chromosome changes from a b c d e f g h to a b c d e f g h g h, where genes g and h are duplicated.

What is chromosomal inversion?

Chromosomal inversion occurs when the order of genes in a chromosomal segment is reversed by 180 degrees. This can affect the chromosome's functionality.

What are the two types of chromosomal inversion?

The two types of chromosomal inversion are paracentric inversion (where the centromere is not involved) and pericentric inversion (where the centromere is included in the inverted segment).

What is translocation in chromosomal aberrations?

Translocation is a chromosomal abnormality in which segments of chromosomes are exchanged between non-homologous chromosomes. There are two types: reciprocal and non-reciprocal translocation.

How do heterozygous and homozygous translocations differ?

In heterozygous translocation, one chromosome is normal and the other has exchanged segments, while in homozygous translocation, both chromosomes involved have exchanged segments.