Genome mapping — A chromosome map that uses cloned and sequenced DNA fragments (e.g., restriction fragments, contigs, sequence-tagged sites) rather than classical genetic markers is known as what?

Biotechnology Animal Biotechnology Chromosomes Difficulty: Easy
Choose an option
  • A
    A physical map
  • B
    A genetic map
  • C
    A cloning map
  • D
    None of these
  • E
    An epigenetic map

Answer

Correct Answer: A physical map

Explanation

Introduction / Context:Genome maps come in multiple types. Genetic (linkage) maps order markers based on recombination frequencies in crosses. Physical maps place DNA features according to actual base-pair distances along chromosomes using molecular tools such as restriction mapping, BAC contigs, and sequence assemblies. Understanding the distinction is vital for positional cloning and genome assembly.

Given Data / Assumptions:

  • Question emphasizes cloned and sequenced DNA fragments.
  • Focus is on absolute order and distances in base pairs, not recombination frequency.
  • Terminology follows standard genomics usage.

Concept / Approach:A physical map represents the literal arrangement of DNA sequences. Early physical maps used restriction fragment maps and overlapping clone contigs; modern approaches rely on long-read sequencing and scaffolding to create near-complete assemblies. Genetic maps complement physical maps but can differ due to recombination hot/cold spots.

Step-by-Step Solution:

Identify the map type that uses cloned/sequenced fragments → physical map.Differentiate from genetic map (recombination-based).Exclude vague or nonstandard terms like “cloning map.”

Verification / Alternative check:Human genome project milestones included both a high-resolution physical map of BAC contigs and genetic linkage maps; both were necessary but distinct.

Why Other Options Are Wrong:

b) Genetic maps use centiMorgan distances based on recombination, not cloned fragment positions.c) “Cloning map” is not a standard map category in genomics.d) A correct option exists.e) Epigenetic maps profile chromatin marks or methylation, not cloned fragment positions.

Common Pitfalls:Assuming higher recombination frequency equals larger physical distance; recombination landscapes vary significantly across genomes.

Final Answer:A physical map.

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