#genomics

BOTANY

Which of the following best describes the function of the Human Genome Project (HGP)?

The Human Genome Project aimed to identify all human genes and determine the complete DNA sequence of the human genome. This follows from latest NCERT 2026-27 principle explaining the concept clearly for NEET students in simple steps as per rationalized syllabus.

Ref: NCERT Biology Textbook - Latest Edition for Academic Session 2026-27 (Botany section, Rationalized Textbook for Class XI and XII), Chapter: Biology - Botany portion (Latest NCERT Textbooks for Academic Session 2026-27 -

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Sequencing

The Sanger sequencing result reads DNA from:

RNA sequencing analysis begins with mapping reads to a reference genome using splice-aware aligners that handle exon-intron boundaries to identify novel transcripts. This computational step reveals transcript structure, exon connectivity, and novel junctions indicating alternative splicing or gene fusion events absent from annotation databases. Reverse transcription creates complementary DNA copies, while library preparation adds adapters for flow cell binding. Sequencing depth determines sensitivity for low-abundance transcripts, but identification of structural novelty depends critically on alignment patterns. Accurate alignment therefore enables discovery of isoform diversity across conditions.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Sequencing

In NGS, what is the principle of sequencing-by-synthesis?

Sequencing-by-synthesis is the core principle of Illumina next-generation sequencing. Library fragments immobilized on flow cell are amplified into clusters, then polymerase synthesizes complementary strand stepwise. Each cycle adds fluorescently labeled reversible terminator dNTPs that block further extension until imaging is complete. After color detection identifying base, terminator and fluorophore are chemically cleaved to allow next incorporation. This iterative labeled nucleotide addition contrasts with ligation-based SOLID, hybridization microarrays relying on probe annealing, or pH change detection in Ion Torrent. Hence labeled nucleotide addition defines SBS.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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Transcriptome analysis

Which invention is credited to Patrick O. Brown?

Patrick O. Brown, at Stanford University, introduced the concept of printing defined DNAs onto glass slides via robotic spotting in 1995. His laboratory demonstrated that differently labeled cDNAs from two samples could competitively hybridize to such arrays to quantify differential gene expression genome-wide. This innovation founded modern transcriptomics, enabling simultaneous monitoring of thousands of genes, shifting paradigm from single-gene northern blots. Fluorescence In Situ Hybridization, RNA sequencing, and CGH were developed by different groups focusing on cytogenetics and sequencing, not array-based expression profiling credited to Brown.

Ref: NCERT Biology Class XII Principles on Klenow fill-in labeling, Lehninger Chapter 9 DNA cloning techniques, and Molecular Cloning by Sambrook Chapter 10 documenting end-labeling of cohesive termini.

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