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What is conjugation?

Transfer of DNA directly between bacterial cells through physical contact. unidirectional

What is transformation?

Uptake of free DNA from the environment into bacterial cells.

What is transduction?

Transfer of genetic material between bacteria by viruses (bacteriophages).

What is minimal medium?

Growth medium containing salts, NH4+, and glucose.

What is complete medium?

Minimal medium supplemented with yeast extract or amino acids.

What are prototrophs?

Wild-type bacteria that can grow on minimal medium.

What are auxotrophs?

Mutant bacteria that require additional nutrients to grow.

What is the F+ factor?

A fertility plasmid that allows bacteria to act as DNA donors during conjugation.

What is a plasmid?

Small, circular, extrachromosomal DNA that replicates independently of the bacterial chromosome.

What is a time clock or time map?

A genetic map showing bacterial gene order and relative distances based on the time required for gene transfer during conjugation.

What are the three processes of bacterial genetic transfer?

Conjugation, transformation, and transduction.

What is the main difference between conjugation, transformation, and transduction?

Conjugation requires cell contact; transformation involves uptake of free DNA; transduction uses viruses to transfer DNA.

Why is conjugation considered unidirectional?

DNA transfers from the donor (F+) to the recipient (F−).

Does conjugation require physical contact?

Yes, donor and recipient bacterial cells must physically contact each other.

Does transformation require physical contact between bacteria?

No, bacteria take up free DNA from the environment.

Does transduction require physical contact between bacteria?

No, bacteriophages transfer DNA between bacterial cells.

What is the chromosome structure of bacteria?

Bacteria are haploid and typically have one circular chromosome.

Why are mutations directly expressed in haploid bacteria?

There is no homologous chromosome to mask the effects of mutations.

Do bacteria undergo mitosis or meiosis?

No, bacteria do not undergo mitosis or meiosis.

What is vertical gene transfer?

Transfer of genetic information from parent cells to daughter cells.

What is horizontal gene transfer?

Transfer of genetic information between bacteria rather than from parent to offspring.

What are the characteristics of plasmids?

Circular double-stranded DNA that replicates independently and may contain genes that provide advantages.

What are the different types of plasmids?

F plasmids, R plasmids, and Col plasmids.

What is the function of an F plasmid?

Contains genes for sex pilus formation and enables conjugation.

What is the function of an R plasmid?

Contains genes that confer antibiotic resistance and allow plasmid transfer.

What is the function of a Col plasmid?

Produces colicins that can kill neighboring bacteria.

What is an F+ strain?

A bacterial strain containing the F plasmid that can act as a donor.

What is an F− strain?

A bacterial strain lacking the F plasmid that acts as a recipient.

What happens when an F+ cell conjugates with an F− cell?

The F plasmid is copied into the F− cell, converting it into F+.

Does the F+ donor lose its F plasmid during conjugation?

No, the donor retains the F plasmid.

What is an Hfr strain?

A high-frequency recombination strain in which the F plasmid is integrated into the bacterial chromosome.

What is the main difference between F+ and Hfr strains?

F+ transfers the F plasmid; Hfr transfers bacterial chromosomal genes because the F factor is integrated into the chromosome.

What happens when an Hfr cell conjugates with an F− cell?

Bacterial chromosomal genes are transferred and may recombine with the recipient chromosome.

Does an F− recipient usually become F+ after mating with an Hfr strain?

No, because the entire F factor is rarely transferred.

Why is chromosomal gene transfer more frequent in Hfr strains?

The F factor is integrated into the chromosome, allowing chromosomal DNA to be transferred during conjugation.

What is the interrupted mating technique?

A method of determining bacterial gene order by stopping conjugation at different times and identifying which genes have entered the recipient.

Which bacterial strains are required for interrupted mating?

An Hfr donor and an F− recipient.

How is gene order determined using interrupted mating?

Genes entering the recipient earliest are closest to the transfer origin; later genes are farther away.

How does conjugation time affect the number of genes transferred?

Longer conjugation allows more bacterial genes to enter the recipient.

How is distance measured in an interrupted mating time map?

By the difference in minutes between the entry times of two genes.

If gene A enters at 5 minutes and gene B enters at 15 minutes, what is their map distance?

10 minutes.

Why is the F factor rarely transferred completely during Hfr conjugation?

Conjugation usually ends before the entire bacterial chromosome and remaining F factor can be transferred.

How does physical distance affect the likelihood that two bacterial genes are transferred together?

Genes closer together are more likely to be transferred together and included in the same recombination event.

What is an F' plasmid?

An F plasmid that has excised from the chromosome and carries some bacterial chromosomal genes.

What is the genome structure of viruses?

Viruses have haploid genomes.

What is a virulent virus?

A virus that infects and lyses (destructs) host cells.

What is a lysogenic virus?

A temperate virus that can integrate its DNA into the bacterial chromosome and replicate with the host.

What is the difference between lytic and lysogenic cycles?

Lytic replication produces viruses and lyses the host; lysogenic replication maintains viral DNA in the host chromosome.

What is cotransduction?

The simultaneous transfer of two linked bacterial genes by a bacteriophage. still uni direction

How does gene distance affect cotransduction frequency?

Genes closer together have a higher frequency of cotransduction.

How are viral genes mapped using recombination data?

By measuring recombinant phage offspring frequencies; higher recombination indicates greater genetic distance.