A host cell normally does not take up a foreign DNA until it has been made competent to do so. This is because:

1. DNA is a hydrophilic molecule

2. DNA is a very large molecule

3. there are no receptors for DNA on the cell membrane

4. DNA is an inert molecule

The first type II restriction endonuclease discovered that could cut dsDNA specific site was:

1. EcoRI

2. SmaI

3. Hind II

4. Hind III

Which statement regarding restriction endonucleases is NOT correct?

1. They recognize a specific base sequence in the DNA.

2. They are produced by bacterial cells as a primitive immune system.

3. They digest DNA by removing nucleotides from a free 3' end.

4. They often generate stick ends.

What limitation of traditional hybridization used for plant and animal breeding has been overcome by

the use of rDNA techniques?

1. High cost

2. Insertion of undesirable genes

3. Complexity of the procedure

4. Antigenicity of the product

Which of the following restriction sites is located within the gene for tetracycline resistance in the plasmid pBR322?

1. BamHI

2. Psti

3. Clal

4. Pvull

The technique not used for transformation of plant cells in recombinant procedures is:

1. Biolistics

2. Agrobacterium mediation

3. Use of viruses

4. Micro-injection

In the screening process during rDNA experiments, clones that metabolize $\beta$-gal turn:

1. Colorless

2. Blue

3. Yellow

4. Green

The plasmid pBR322 does not contain:

Restriction enzymes are synthesized by:

1. Bacteria only

2. Yeast and bacteria only

3. Eukaryotic cells only

4. All kinds of cells

The process of separation and purification of expressed protein before marketing is called

(1) upstream processing

(2) downstream processing

(3) bioprocessing

(4) postproduction processing