Cloning Vectors and Hosts Quiz

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Questions and Answers

Which of the following characteristics is NOT ideal for host organisms used in cloning vectors?

Capable of incorporating DNA

Capable of rapid growth in inexpensive medium

Genetically stable in culture

Pathogenic nature (correct)

Which bacterium is best known for its role in genetic studies and as a host for cloning vectors?

Staphylococcus aureus

Saccharomyces cerevisiae

Escherichia coli (correct)

Bacillus subtilis

What advantage does Bacillus subtilis have over Escherichia coli as a cloning host?

It forms endospores. (correct)

It has well-developed genetics.

It can process mRNA and proteins.

It does not secrete proteins.

What is a common disadvantage of using eukaryotic host organisms for cloning vectors?

They cannot replicate bacterial plasmids. Signup and view all the answers

Which method is typically used by restriction endonucleases to cleave DNA?

Recognizing specific nucleotide sequences and cutting at these sites Signup and view all the answers

What is a primary function of restriction endonucleases?

To cut DNA at specific sequences Signup and view all the answers

Which of the following factors does NOT influence cloning efficiency?

Color of the plasmid Signup and view all the answers

Why are restriction endonucleases considered essential tools for recombinant DNA technology?

They cut DNA into specific size fragments Signup and view all the answers

What is the typical origin of restriction endonucleases?

Bacteria Signup and view all the answers

What aspect of restriction endonucleases helps protect bacterial cells?

By hydrolyzing viral nucleic acids Signup and view all the answers

What is the characteristic cutting behavior of Type I restriction enzymes?

They cut randomly, far from the recognized site. Signup and view all the answers

Which type of restriction enzyme recognizes a specific sequence yet cuts at a location within 25 base pairs?

Type III Signup and view all the answers

How long are the target sites for Type II restriction endonucleases?

4-8 base pairs Signup and view all the answers

What is the result of the action of a restriction enzyme that produces a 5' overhang?

Sticky ends with a single-stranded segment extending from the ends. Signup and view all the answers

What type of DNA ends are generated by restriction enzymes when they cut at palindromic sequences?

5' and 3' sticky ends. Signup and view all the answers

Which enzyme is responsible for sealing the DNA strands after the restriction enzyme has cut the DNA?

DNA ligase Signup and view all the answers

What is a key feature of the recognition sequences for restriction enzymes?

They are typically 4- or 6-base pair palindromic sequences. Signup and view all the answers

What is the optimal outcome of a DNA fragment being cut by the same restriction enzyme?

The resulting fragments will have complementary overhangs. Signup and view all the answers

Study Notes

Hosts for Cloning Vectors

Ideal hosts for cloning vectors should be capable of rapid growth in inexpensive media.
Hosts should be nonpathogenic.
Hosts should be able to incorporate DNA.
Hosts should be genetically stable in culture.
Hosts should have appropriate enzymes for vector replication.

Common Cloning Hosts

Bacteria: Escherichia Coli, Bacillus subtilis
Eukaryotes: Saccharomyces cerevisiae

What Determines the Choice of Vector?

Insert size
Vector size
Restriction sites
Copy number
Cloning efficiency
Ability to screen for inserts

Restriction Endonucleases

Enzymes that cleave (cut) DNA at specific unique internal locations.
Essential tools for recombinant DNA technology.
Cut within DNA molecules at a specific DNA sequence.
Discovered in the late 1970s.
Essential for protecting bacterial cells from viral infection.

Restriction Enzyme Types

Type 1: Enzymes recognize DNA sequences, but cuts are random and far away from the recognized site.
Type 2: Enzymes recognize and cut within the recognized site. These are the most commonly used type.
Type 3: Enzymes recognize sequences but cut at a different location within 25 base pairs of the recognized site.

Type II Restriction Endonucleases

Recognize and cut within 4-8 base pair palindromic sequences.

Mode of Action of Restriction Enzymes

Restriction Enzymes cut DNA at a specific sequence called a "restriction site."
Enzymes recognize 4- or 6-base pair palindromic sequences.
Enzymes may generate 5' overhangs or 3' overhangs depending on the specific enzyme.

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Description

Test your knowledge on cloning vectors and hosts with this quiz. It covers the ideal characteristics of hosts, the types of common cloning hosts, and the role of restriction endonucleases. Challenge yourself and see how well you understand recombinant DNA technology!