Biotechnology

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Slide 22

Storing Cloned Genes in DNA Libraries

A genomic library that is made using bacteria is the collection of recombinant vector clones produced by cloning DNA fragments from an entire genome

A genomic library that is made using bacteriophages is stored as a collection of phage clones

Slide 23

Fig. 20-5

Bacterial clones

Recombinant plasmids

Recombinant phage DNA

or

Foreign genome cut up with restriction enzyme

(a) Plasmid library

(b) Phage library

(c) A library of bacterial artificial chromosome (BAC) clones

Phage clones

Large plasmid

Large insert with many genes

BAC clone

Slide 24

Fig. 20-5a

Bacterial clones

Recombinant plasmids

Recombinant phage DNA

or

Foreign genome cut up with restriction enzyme

(a) Plasmid library

(b) Phage library

Phage clones

Slide 25

A bacterial artificial chromosome (BAC) is a large plasmid that has been trimmed down and can carry a large DNA insert

BACs are another type of vector used in DNA library construction

Slide 26

Fig. 20-5b

(c) A library of bacterial artificial chromosome (BAC) clones

Large plasmid

Large insert with many genes

BAC clone

Slide 27

A complementary DNA (cDNA) library is made by cloning DNA made in vitro by reverse transcription of all the mRNA produced by a particular cell

A cDNA library represents only part of the genome—only the subset of genes transcribed into mRNA in the original cells

Slide 28

Fig. 20-6-1

DNA in nucleus

mRNAs in cytoplasm

Slide 29

Fig. 20-6-2

DNA in nucleus

mRNAs in cytoplasm

Reverse transcriptase

Poly-A tail

DNA strand

Primer

mRNA

Slide 30

Fig. 20-6-3

DNA in nucleus

mRNAs in cytoplasm

Reverse transcriptase

Poly-A tail

DNA strand

Primer

mRNA

Degraded mRNA

Slide 31

Fig. 20-6-4

DNA in nucleus

mRNAs in cytoplasm

Reverse transcriptase

Poly-A tail

DNA strand

Primer

mRNA

Degraded mRNA

DNA polymerase

Slide 32