Which is TRUE for MACs?
Mammalian artificial chromosomes are engineered vectors designed for stable maintenance and expression in mammalian cells. They contain mammalian centromere, telomeres, replication origins and selection markers functional in mammalian systems. Unlike yeast or bacterial vectors with limited 100-300 kb capacity, MACs can carry megabase-sized inserts exceeding 1000 kb, enabling transfer of entire gene clusters and regulatory regions. They replicate extrachromosomally without integrating into host chromosomes, reducing insertional mutagenesis risk. Applications include gene therapy models, large transgene delivery and studying chromosome structure in human or murine cell lines.
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.