MICRO 3050: Unit 4 Bacterial Genetics

component cells are cells that

can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination

What characteristic of the S strain allows it to evade the immune system of the mice?

The cells have a capsule

What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells?

The R strain picked up the S strain DNA, enabling it to produce a capsule

Which finding is most surprising from Griffith’s experiments?

S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains

Mice that are injected with only the R strain of Streptococcus pneumoniae ____

stay healthy, because their immune systems can kill this strain easily

What is unique about transduction compared to normal bacteriophage infection?

Transduction transfers DNA from the chromosome of one cell to another

How is generalized transduction different from specialized transduction?

Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage

A transducing phage

contains fragments of the host chromosome instead of the viral genome

When a transducing phage interacts with a new host cell ____

the DNA from the previous host can recombine with the new host chromosome

How does specialized transduction differ from regular lysogeny?

The prophage in specialized transduction carries with it pieces of the host chromosomal DNA

What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?

The host DNA integrates, with the prophage, into the new recipient chromosome

How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population?

The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.

process of conjugation

1. pilus retracts

2. cell pairs stabilized (F plasmid nicked in one strand)

3. one strand transferred from F+ cell to F- cell; F plasmid replicated in F+ cell

4. recipient cell begins synthesis of complementary strand

5. cells separate after completion of DNA transfer and synthesis

What is the function of the conjugation pilus?

It pulls the F+ and F- cells together.

What is required by an F- cell to become an F+ cell?

F plasmid

What is the key difference between donor cells and recipient cells?

An F plasmid

What cellular macromolecule is the fertility factor comprised of?

Nucleic acid

At which point does a recipient cell become an F+ cell?

Formation of the complementary strand of the F factor

How do restriction enzymes cut DNA sequences?

They cut DNA at sites, called recognition sites, that have specific nucleotide sequences

In general, how might recombinant DNA technology be used to prevent a genetic disorder caused by a mutation in a single gene?

To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene

Which of the following attaches the target gene to a desired location?

DNA ligase

Why would a recombinant DNA molecule be inserted into a host cell?

It can be copied, transcribed, and translated into a desired protein

events in microbial pathogenesis

exposure→adhere to skin/mucosa→invasion→infection→toxicity→tissue damage/disease