Question

Arrange the following techniques in order, from largest to smallest, in terms of the size of the genetic abnormality each could detect.

I. Comparative genome hybridization
II. G-banding
III. Allele specific oligonucleotide hybridization
IV. Fluorescent in situ hybridization (FISH)

a) I, II, III, IV
b) II, IV, III, I
c) IV, II, III, I
d) II, IV, I, III
e) I, II, IV, III

Answer 1

The order of techniques from largest to smallest detectable genetic abnormalities is G-banding, FISH, comparative genome hybridization, and ASO hybridization.

Step-by-step explanation:

To answer the student's question regarding the order of techniques from largest to smallest genetic abnormalities they can detect, we start by understanding each technique:

• G-banding (II) is a cytogenetic technique where chromosomes are stained and viewed under a microscope. This allows for the visualization of banding patterns on chromosomes that represent large-scale structural features, such as deletions or duplications.
• Fluorescent in situ hybridization (FISH) (IV) is a molecular cytogenetic technique that can be used to identify the presence or absence of specific DNA sequences, providing higher resolution than G-banding but still at a fairly large scale.
• Comparative genome hybridization (I) is a technique used to detect copy number variations (gains or losses) of DNA segments throughout the entire genome and can find abnormalities smaller than those detected by FISH.
• Allele-specific oligonucleotide (ASO) hybridization (III) is a method that involves using small pieces of DNA (oligonucleotides) that are designed to specifically bind to known variants of a gene and can detect single nucleotide polymorphisms (SNPs), the smallest type of genetic variation.

Therefore, the correct order from largest to smallest detectable abnormalities would be G-banding (II), FISH (IV), comparative genome hybridization (I), and allele specific oligonucleotide hybridization (III).