Biology Week 6 Flashcards

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Questions and Answers

Preventing the function of light repair (photoreactivation) interferes with the repair of which of the following?

thymine dimers

The classic transformation experiment done by Griffith used:

harmless and virulent strains of Streptococcus pneumoniae

Recombination is defined as:

one bacterium donating DNA to another

In addition to transformation, the other two forms of horizontal gene transfer are:

conjugation and transduction Signup and view all the answers

In the beginning of transformation, ______ binds to the target cell.

double-stranded DNA Signup and view all the answers

During the entry of the donor DNA into the recipient cell, what happens?

one strand is broken down by nucleases Signup and view all the answers

Mismatch repair is activated by:

any difference between the nucleotide sequence in the donor and recipient DNAs Signup and view all the answers

The donor DNA pairs with a homologous region of the recipient DNA.

true Signup and view all the answers

As a result of mismatch repair during transformation:

cells may have either original DNA or donor DNA in them Signup and view all the answers

During the process of transformation in the lab setting, cells are plated on selective media to:

make sure that only transformants grow Signup and view all the answers

Cells that are capable of bringing DNA from their environment into the cell are called:

competent Signup and view all the answers

Transformation is facilitated by:

proteins on the cell wall that bind DNA from the environment Signup and view all the answers

A culture of E. coli is irradiated with UV light. The UV light affects the cell's DNA by:

forming covalent bonds between thymine bases on the same strand of DNA Signup and view all the answers

Bacterial cells that have been genetically modified to carry an antibiotic resistance gene can be separated from susceptible microbes by using a _______ selection method using agar plates with antibiotic.

direct Signup and view all the answers

On which of the following DNA strands will UV light have the most effect?

ACTTGCTTAC Signup and view all the answers

A prototroph can grow on glucose-salts media.

True Signup and view all the answers

Plasmids are:

able to replicate independently of the chromosome Signup and view all the answers

A recombinant organism is:

one that contains genes from another organism Signup and view all the answers

If you find that a particular plasmid has an R factor, the bacteria that has it will be:

resistant to antibiotics Signup and view all the answers

F+ cells:

have a plasmid and are donors in conjugation Signup and view all the answers

The F pilus binds to:

specific receptors on the cell wall of the recipient Signup and view all the answers

The F pilus is:

a protein appendage that attaches the two cells Signup and view all the answers

The plasmid is mobilized for transfer when:

an endonuclease cleaves it at the origin of transfer Signup and view all the answers

Plasmid DNA is transferred:

in single-stranded form Signup and view all the answers

The F plasmid encodes for:

the F-pilus Signup and view all the answers

The first step in conjugation is:

contact between the donor and recipient cells Signup and view all the answers

After the transfer of the F plasmid is complete:

the F- cell becomes F+ Signup and view all the answers

If Gene X codes for an F pilus and transposition occurs, then the bacterium containing the plasmid would:

no longer be able to conjugate Signup and view all the answers

Repair mechanisms that occur during DNA synthesis are:

mismatch repair and proofreading by DNA polymerase Signup and view all the answers

Genes from the donor chromosome are transferred as:

single-stranded DNA Signup and view all the answers

After the conjugation of an Hfr cell with an F- cell:

the recipient remains F- Signup and view all the answers

During conjugation, the donor chromosome is transferred as:

single-stranded DNA Signup and view all the answers

Which of the following genes are likely to be found on a plasmid rather than on the bacterial chromosome?

Superoxide dismutase gene Signup and view all the answers

Which of the following statements is/are TRUE?

Wild type E. coli must be provided with the amino acid histidine in order to grow. Signup and view all the answers

Study Notes

DNA Repair and Transformation

Photoreactivation prevents the repair of thymine dimers.
Griffith's classic transformation experiment involved harmless and virulent strains of Streptococcus pneumoniae.
Transformation is a form of recombination involving one bacterium donating DNA to another.

Horizontal Gene Transfer

Besides transformation, conjugation and transduction are other forms of horizontal gene transfer.
Double-stranded DNA binds to the target cell during the initial stage of transformation.
Nucleases break down one strand of the donor DNA during its entry into the recipient cell.

DNA Mismatch Repair

Mismatch repair is triggered by any difference between nucleotide sequences of donor and recipient DNA.
Donor DNA pairs with a homologous region in the recipient DNA.

Transformation Outcomes

Following mismatch repair, cells may contain either original DNA or donor DNA.
In laboratory settings, selective media is used to ensure that only transformants grow.
Competent cells can uptake DNA from their surroundings through their cell walls.

DNA Damage and UV Light

UV light effects on DNA include forming covalent bonds between thymine bases on the same strand.
Direct selection methods using agar plates with antibiotics can separate genetically modified bacteria carrying antibiotic resistance genes from non-resistant strains.

Genetic Elements

A prototroph can thrive on glucose-salts media.
Plasmids can replicate independently of bacterial chromosomes and can carry antibiotic resistance genes.
Recombinant organisms contain genes from another organism.

Conjugation Mechanisms

F+ cells possess a plasmid and serve as donors in conjugation.
The F pilus binds to specific receptors on the recipient cell's wall and facilitates the attachment of the two cells.
An endonuclease cleaves the plasmid at the origin of transfer to initiate mobilization.

DNA Transfer Process

Plasmid DNA is transferred in single-stranded form during conjugation.
The F plasmid encodes the production of the F-pilus.
The initial step in conjugation is contact between the donor and recipient cells.

Plasmid and Chromosome Interactions

After the complete transfer of the F plasmid, the F- cell becomes F+.
Transposition of Gene X, which codes for an F pilus, can disrupt a bacterium's ability to conjugate.

Repair Mechanisms

DNA synthesis repair mechanisms include mismatch repair and proofreading by DNA polymerase.
Genes from the donor chromosome are also transferred in single-stranded form during conjugation.

Genetic Mutations and Growth Requirements

After an Hfr cell conjugates with an F- cell, the recipient remains F-.
Genes such as ATP synthase and superoxide dismutase are likely found on plasmids rather than on the bacterial chromosome.
Wild type E. coli require the amino acid histidine for growth, and missense mutations generally have more significant consequences than frameshift mutations.

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Description

Test your knowledge with these flashcards covering key concepts from biology for Week 6. Topics include DNA repair mechanisms, transformation experiments, and bacterial recombination. Perfect for students looking to reinforce their understanding of genetics and microbiology.