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#base pairs

2 public questions tagged with this topic.

Recombination

Length of loxP site is

loxP is a 34 base-pair site derived from bacteriophage P1 locus of crossover. Architecture comprises two 13 base-pair palindromic Cre recombinase binding elements arranged as inverted repeats flanking central 8 base-pair asymmetric spacer where strand exchange occurs. Each 13 base-pair half is recognized by one Cre monomer, so synaptic tetramer contains four Cre bound to two loxP sites. Spacer asymmetry confers directionality; identical orientation of two sites leads to excision, opposite orientation leads to inversion. Tolerance to few mismatches in outer repeats allows engineering of incompa

Ref: Watson et al., Molecular Biology of the Gene, 7th ed., Chapter 12: loxP Site 34 bp Structure and Organization

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Molecular Marker

Which repeat type is >100 base pairs?

Tandem repetitive DNA is classified by repeat unit length and array size. Microsatellites, SSR or STR, contain 1-6 bp motifs, minisatellites or VNTR contain 10-100 bp motifs, while macrosatellites exceed 100 bp and can span kilobases, forming large heterochromatic blocks at centromeres, telomeres and heterochromatic regions. The greater than 100 base pair definition distinguishes macrosatellite organization, which often shows higher-order repeat structure, epigenetic silencing and copy number variation. Such large repeats are unsuitable for standard PCR microsatellite assays but crucial for ch

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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