An enzyme that joins the ends of two strands of nucleic acid is a

polymerase
synthetase
helicase
ligase

Introduction of one or more genes into an organism which normally does notpossess them or their deletion by using artificial means (not by breeding) comes under

molecular biology
cytogenetics
genetic hybridization
genetic engineering

Solution

Genetic engineering is the science of gene manipulation. It involves the isolation, manipulation, transfer, and reintroduction of DNA into cells or model organisms usually to express a protein. The aim is to introduce new characteristics or attributes physiologically or physically,such as making a crop resistant to a herbicide, introducing a novel trait, or producing a new protein or enzyme, along with altering the organism to produce more of certain traits.

Which one of the following pairs is not correctly matched

Plasmid – Small piece of extrachromosomal DNA in bacteria
Interferon– An enzyme that interferes with DNA replication
Cosmid – Avector for carrying large DNA fragments into host cells
Myeloma – Antibody – producing tumour cells

Solution

Interferons are antiviral proteins produced by recombiant DNA technology in E.coli.

DNA fragments are separated using gel electrophoresis

because DNA is pulled through the gel toward the negative end of the field.
because larger DNA fragments move faster through the gel than smaller DNA fragments.
to identify and isolate DNA fragments.
to synthesize DNA for cloning.

Solution

DNA fragments migrate toward the positive end of the electrical field with the smallest fragments migrating the fastest.

Vectors include

bacterial and plant plasmids
viruses
artificial chromosomes
All of the above

Complementary base pairing is important for

ligation reactions with blunt-end DNA molecules.
hybridization between DNA and transcription factors.
restriction endonucleases to cut cell walls.
synthesizing cDNA molecules from mRNA templates.

In order for a prokaryotic vector to be propagated in a host bacterial cell, the vector needs

telomeres.
centromeres.
drug resistant genes.
an origin of replication

Solution

A prokaryotic vector needs an origin of replication to be propagated in a prokaryotic cell.

Vectors include

bacterial and plant plasmids
viruses
artificial chromosomes
All of the above

Solution

All of these molecules can serve as vectors for cloned DNA.

Cloning means that

all of the cells are derived from one cell and are genetically identical.
a gene from one organism has been inserted into a vector and successfully introduced into a host cell.
all of the cells in a particular organism are identical.
All of the above

Recombinant DNA can be transferred into host cell by

growing the host cell in growth medium containing ampicillin.
coating the DNA with carbohydrates so that the cells will engulf the DNA.
treating cells with calcium ions or electrical pulses to increase cell permeability.
injecting proteins into host cells to make them more permeable.

Solution

Treating cells with ampicillin does not make them more permeable to DNA. Coating DNA with lipids (not carbohydrates) is used to introduce recombinant DNA molecules into host cells, injecting DNA (not protein) isa method used to place recombinant DNA into best cells.

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