Q.48 Identify the correct sequence of genome of different organisms in increasing order
A.Homo sapians
B.Escherichia coli
C.Drosophila melanogaster
D.Saccharomyces cerevisiae
E.Caenorhabditis elegans
Choose the correct answer from the options given below :
(1) A, B, C, D, E
(2) B, C, D, E, A
(3) B, D, E, C, A
(4) E, D, C, B, A
Genome sizes increase from Escherichia coli (4.6 Mb) < Saccharomyces cerevisiae (12 Mb) < Caenorhabditis elegans (100 Mb) < Drosophila melanogaster (180 Mb) < Homo sapiens (3.2 Gb), making option (3) B, D, E, C, A correct.
Question Breakdown
This tests model organism genome sizes, standard knowledge for GATE Life Sciences genomics. Sequence reflects prokaryote → unicellular eukaryote → invertebrate → vertebrate progression, ignoring C-value paradox exceptions.
Option Analysis
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(1) A, B, C, D, E: Wrong; human genome largest, E. coli smallest.
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(2) B, C, D, E, A: Wrong; fly (C: 180 Mb) > worm (E: 100 Mb).
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(3) B, D, E, C, A: Correct → E. coli (4.6 Mb) → Yeast (12 Mb) → Worm (100 Mb) → Fly (180 Mb) → Human (3.2 Gb).
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(4) E, D, C, B, A: Wrong; worm (100 Mb) > yeast (12 Mb).
Genome sequence organisms increasing order follows E.coli < yeast < C.elegans < Drosophila < human, essential for GATE Life Sciences genomics MCQs comparing model organisms. Prokaryotic (4.6 Mb) to human (3.2 Gb) reflects complexity progression.
Genome Sizes Table
| Organism | Genome Size | Genes | Notes |
|---|---|---|---|
| B E. coli | 4.6 Mb | ~4,300 | Prokaryote |
| D Yeast | 12 Mb | ~6,000 | Unicellular eukaryote |
| E C. elegans | 100 Mb | ~20,000 | Nematode |
| C Drosophila | 180 Mb | ~14,000 | Insect |
| A Human | 3.2 Gb | ~20,000 | Vertebrate |
Model Organism Significance
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E. coli: Molecular cloning standard.
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Yeast: Eukaryotic genetics (S. cerevisiae).
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C. elegans: First multicellular genome (1998).
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Drosophila: Developmental genetics.
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Human: HGP reference (2003).
Exam Strategy
GATE tests exact sizes: Memorize 4.6 → 12 → 100 → 180 → 3200. Trap: Fly-worm confusion (Drosophila > C.elegans). Key: Human 1000x bacterial despite similar gene count (C-value paradox).
