# DBT JRF 2020 — Question 132

Exam: DBT JRF 2020 · Section: B · Topic: Genetics · Difficulty: Medium

## Question

Which one of the following approaches is generally not used for identifying an SNP?

## Options

- **A.** protein sequencing
- **B.** microarrays
- **C.** molecular beacons
- **D.** RNA Seq

## Answer

Option A

## Explanation

SNP identification methods: (1) Whole genome sequencing (WGS) — directly identifies SNPs at base-pair resolution. (2) RNA-Seq (transcriptome sequencing) — identifies SNPs in expressed regions (exonic SNPs/eQTLs). (3) DNA microarrays (SNP chips, e.g. Illumina BeadChip, Affymetrix) — hybridisation-based genotyping of hundreds of thousands of SNPs simultaneously. (4) Molecular beacons — stem-loop oligonucleotide probes with a fluorophore and quencher; hybridise to target and discriminate single nucleotide mismatches by fluorescence. (5) TaqMan genotyping, pyrosequencing, KASP assay — SNP genotyping methods. PROTEIN SEQUENCING (Edman degradation or MS/MS): sequences the amino acid chain — can detect amino acid polymorphisms but CANNOT directly identify the underlying nucleotide change (same amino acid can be encoded by different SNP-containing codons; synonymous SNPs are completely invisible to protein sequencing). Therefore protein sequencing is NOT generally used for SNP identification.

Source: https://mypyqbuddy.com/questions/which-one-of-the-following-approaches-is-generally-6a05a8a02adafec47029329c