Libraries Flashcards
What design features do primers have?
Tm ~55'C 3' G/C No long complementary repeats 20-30nt long 50% G/C Start/stop codon
What is the cycle of PCR?
94’C denaturisation
55’C annealing
72’C extension
What alternatives can be used for PCR denaturisation?
alkaline denaturisation of DNA
Which polymerases can be used for PCR?
Taq with no exonuclease
Kod/Pfu with 3’-5’ proof reading
How many PCR cycles are required for production of product?
4
How many PCR cycles are used for amplification?
24-30
What is the outline of the cloning protocol?
Purify vector and gene fragment from library
Isolate gene by restriction digestion of PCR
Ligate gene and vector
Transform into colonies
Check recombination by antibiotic resistance or PCR
Extract vector
Transform into expression colony
Isolate protein product
What are libraries?
Collection of fragments of the entire genome contained within a collection of colonies
How is the genome fragmented for libraries?
Partial digestion by high frequency restriction sites (Sau every 250bp) or mechanical
What vectors are used for library production?
lamda phage (20kb) cosmid (40kb)
What are libraries used for?
PCR amplification,
functional/manipulative genomics
How are cDNA libraries produced?
mRNA isolated by oligo(dT) columns for Poly(A) tail
reverse transcriptase produces cDNA
What was the original use of libraries?
Ordered, overlapping libraries for sequencing with radioprobes
What is the modern approach to sequencing of gene fragments from libraries?
Shotgun approach fragments genome and sequences are aligned without ordering
What are the types of sequencing?
Sanger, Illumina, Maxam Gilbert
How is reannealing of DNA prevented during Sanger sequencing?
Heated to denature and high [primer]