Biotechnology Flashcards
What is a recombinant plasmid?
It’s a plasmid with foreign DNA being inserted into it.
What do restriction enzymes do?
These cut DNA molecules at specific DNA sequences called restriction sites. This results in restriction fragments.
What part exactly do restriction enzymes cut?
They cut sugar-phosphate backbones.
What is a cloning vector?
It is the original plasmid.
What is a genomic library?
A genomic library 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)
What is a bacterial artificial chromosome (BAC)?
It 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.
What is the cDNA library (complimentary DNA library)?
It is a library that contains genes that are expressed in the cell at a given point of time.
It is made by cloning DNA made in vitro by reverse transcription of all the mRNA produced by a particular cell.
What are the differences between genomic DNA library and cDNA library?
- Genomic DNA library is a representation of all genes, cDNA library is a representation of genes that are expressed. (So cDNA is much smaller)
- Genomic DNA library contains the sequences for both intron and exon. cDNA library contains only exons. (cDNA has less sequence information compared to a genomic DNA library)
- No. of recombinants to be screened is less in cDNA.
How to extract gene of interest?
With a nucleic acid probe having a sequence complementary to the gene. This process is called nucleic acid hybridisation.
How scientists overcome the problem of difficulties that hinder expression of cloned eukaryotic genes in bacterial host cells?
They employ an expression vector, which is a cloning vector that contains a highly active bacterial promoter.
How biologists avoid eukaryote-bacterial incompatibility?
They use eukaryotic cells such as yeasts al hosts. But even yeasts may not possess the proteins required to modify expressed mammalian proteins. So cultured mammalian or insect cells may be used to express and study proteins.
From which electrode DNA segments move in gel electrophoresis?
From negative cathode to positive anode.
What variations in DNA sequence are called?
Polymorphisms
What sequence changes that alter restriction sites are called?
Restriction fragment length polymorphisms
How can we determine the function of the gene?
Disable it and observe the consequences. Introduce mutations into a cloned gene using in vitro mutagenesis, and so, alter or destroy its function. When returning the mutated gene to the cell, normal gene’s function might be determined by examining the mutant’s phenotype.
Gene expression can also be silenced using RNA interference (RNAi). Synthetic double stranded RNA molecules matching the sequence of a particular gene are used to break down or block the gene’s mRNA.
