Prokaryotic Genome

Question 1

Which comparisons between eukaryotic and prokaryotic genomes are true?

Possible Answers:
All of these

Both types of genomes have large spacer regions between genes

Eukaryotic genes are often single and not in operons like prokaryotic genes

Both genomes are replicated in the nucleus

Prokaryotic genomes frequently have many transposable elements

Answer 1

Eukaryotic genes are often single and not in operons like prokaryotic genes

Explanation:
The only true comparison of those listed is that eukaryotic genes are not often present in operons, like prokaryotes often have (think the frequently studied lac operon). Eukaryotes, not prokaryotes, have many transposable elements (a contributing factor to why our genomes are so large). Prokaryotes do not have large spacer regions between their genes, their genomes are often extremely compact. Prokaryotic cells lack nuclei, thus, DNA replication occurs in the cytosol.

Question 2

The Frederick Griffith experiment showed that previously safe pneumococcus can become lethal when it incorporates DNA from the surroundings into its genome.

What type of genetic transfer was displayed in the Frederick Griffiith experiment?

Possible Answers:
Binary fission

Conjugation

Transduction

Transformation

Answer 2

Transformation

Explanation:
When a bacterium has incorporated DNA from the outside environment into its own genome, the process of transformation has occurred.

Question 3

Which type of bacterial genetic recombination involves the use of a viral vector?

Possible Answers:
Assimilation

Transduction

Conjugation

Transformation

Answer 3

Transduction

Explanation:
Sometimes a bacteriophage can encapsulate host bacterial DNA instead of viral DNA. When this virus infects another bacterium, it will inject the previous bacterium’s DNA into the new bacterium. This process is referred to as transduction.

Question 4

What plasmid, usually in multiple copies in a prokaryote, is responsible for production of proteins to attack susceptible organisms?

Possible Answers:
F plasmids

R plasmids

Degradative plasmids

Virulence plasmids

Col plasmids

Answer 4

Col plasmids

Explanation:
The correct answer is the Col plasmid, which produce attack proteins called colicins. These are generally small and in many copies in a prokaryote for efficiency. F plasmids are involved in conjugation, R plasmids in resistance, degradative plasmids in digestion of unusual substances, and virulence plasmids in the conversion of certain bacteria into pathogens.

Question 5

What type of phages facilitate specialized transduction?

Possible Answers:
Lysogenic phages

Lytic phages

Animal viruses

Retroviruses

None of these

Answer 5

Lysogenic phages

Explanation:
Specialized transduction occurs when a prophages excises from the host bacterial genome incorrectly and brings some of the bacterial chromosome with it. This DNA then gets packaged into viral particles along with the viral genome and gets inserted into the next bacterium that virus infects. Since only lysogenic phage can become prophage, specialized transduction can only be mediated by lysogenic phage. Retroviruses are enveloped and thus infect animal cells, not bacterial cells.

Question 6

Bacteria are capable of “sharing” genetic material that can be advantageous in certain environments. This type of gene transmission is an example of which of the following?

Possible Answers:
Fission

Transduction

Transformation

Conjugation

Answer 6

Conjugation

Explanation:
In this example, note that the new genes are being received from a donor bacterium. This is only seen in conjugation events.