6 public questions tagged with this topic.
Cloning vectors must be able to replicate within a host cell to ensure the propagation of the inserted gene.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Cloning Vectors - Plasmids Phages Cosmids Selectable Markers Ori
Cloning vectors do not contain exons and introns; they are designed to carry and replicate inserted genes.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Cloning Vectors - Plasmids Phages Cosmids Selectable Markers Ori
A good cloning vector must have a selectable marker to help identify successfully transformed cells.
Ref: NCERT Class 12 Biology Chapter 9: Biotechnology: Principles and Processes Cloning Vectors - Plasmids Phages Cosmids Selectable Markers Ori
Yeast vectors are categorized by replication behavior. Yeast replicative plasmid YRp carries ARS but lacks centromere, replicates autonomously but unstable. Yeast centromere plasmid YCp contains ARS plus CEN, single-copy stable. Yeast episomal plasmid YEp contains 2-micron origin, high-copy. Yeast integrative plasmid YIp lacks ARS and yeast origin, cannot replicate autonomously, so must integrate into host chromosome via homologous recombination for stable inheritance. Integration occurs at homologous loci, providing stable single copy but low transformation frequency, useful for gene disruption and stable expression studies.
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.
pUC18 is a high-copy-number derivative of pBR322 engineered with modified pMB1 origin, lacZ alpha fragment for blue-white screening and ampicillin resistance. Total plasmid size approximates 2686 base pairs, commonly rounded to 2.7 kb. Due to small backbone, insert size is limited, typically 5-10 kb, before stability declines. The 2.7 kb refers to vector backbone length itself, not maximum insert. Knowledge of precise vector size is important for restriction analysis, estimating recombinant size on agarose gels and calculating molar ratios for ligation reactions in molecular cloning experiments.
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.
Cloning capacity is determined by vector structure and host tolerance for large inserts. Plasmids handle up to 10 kb, lambda phage 20 kb, cosmid around 45 kb, BAC 100-300 kb, YAC 100-2000 kb and mammalian artificial chromosome exceeds 2000 kb. For 200 kb genomic fragments, YAC is optimal among common options because it includes centromere, telomeres and ARS enabling segregation of very large linear eukaryotic DNA in yeast. BAC can accommodate up to 300 kb but 200 kb near upper limit with lower stability. YAC accommodates megabase inserts essential for genome mapping projects.
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.
