MCAT Biological and Biochemical Foundations of Living Systems Flashcards: 2b Prokaryotic Genetics

What this deck covers

This deck focuses on 2b Prokaryotic Genetics, giving you a quick way to review the definitions, rules, and examples that matter most for MCAT Biological and Biochemical Foundations of Living Systems.

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Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is the usual outcome for donor and recipient after F+ × F− conjugation?

Answer: Donor remains F+; recipient becomes F+. During conjugation, a copy of the F plasmid is transferred, allowing both cells to potentially act as donors afterward.

Flashcard 2: Choose the expected recipient outcome: an F+ donor mates with an F− recipient and transfer completes.

Answer: Recipient becomes F+. Complete transfer of the F plasmid copy converts the recipient to a donor, promoting plasmid spread in the population.

Flashcard 3: Which DNA is transferred first during Hfr conjugation?

Answer: Chromosomal DNA adjacent to the integrated F origin of transfer. The origin of transfer site directs the sequential mobilization of DNA starting from the integrated F factor's position.

Flashcard 4: What is the major clinical significance of conjugative R plasmids?

Answer: Rapid horizontal spread of antibiotic resistance between bacteria. Conjugation allows quick dissemination of resistance genes across bacterial populations, complicating infection treatments.

Flashcard 5: Which option best defines bacterial transformation?

Answer: Uptake of naked DNA from the environment by a bacterium. Competent bacteria can incorporate environmental DNA into their genome, facilitating genetic variation without cell contact.

Flashcard 6: Which option describes an F+ cell compared with an F− cell?

Answer: F+ contains the F plasmid; F− lacks the F plasmid. The presence of the F plasmid determines the donor capability in conjugation, distinguishing between donor and recipient cells.

Flashcard 7: Which process requires a bacteriophage: transformation, conjugation, or transduction?

Answer: Transduction. Bacteriophages act as vectors in transduction, unlike the direct contact in conjugation or DNA uptake in transformation.

Flashcard 8: What is the key distinction between generalized and specialized transduction?

Answer: Generalized: any gene; specialized: only genes near prophage site. Generalized involves random DNA packaging during lytic cycle, while specialized requires prophage excision carrying adjacent genes.

Flashcard 9: Which option best defines an R plasmid in bacteria?

Answer: Plasmid carrying antibiotic resistance genes. These plasmids confer survival advantages in antibiotic environments by encoding resistance mechanisms like efflux pumps.

Flashcard 10: What does Hfr stand for?

Answer: High frequency of recombination. This acronym reflects the enhanced rate of genetic recombination due to efficient chromosomal DNA transfer in conjugation.

Flashcard 11: What does it mean for a bacterium to be competent?

Answer: Able to take up exogenous DNA (naturally or artificially induced). Competence involves specific physiological states or treatments that enable DNA binding and uptake across the cell membrane.

Flashcard 12: What is horizontal gene transfer (HGT) in prokaryotes?

Answer: Gene transfer between organisms not via parent-to-offspring inheritance. HGT enables rapid adaptation by acquiring genes from unrelated organisms through mechanisms like conjugation or transformation.

Flashcard 13: What is the term for movement of a DNA segment within a genome or between DNA molecules?

Answer: Transposition. This mechanism allows mobile genetic elements to relocate, contributing to genome evolution and antibiotic resistance spread.

Flashcard 14: Identify the transfer mechanism: uptake of free DNA by a competent bacterium.

Answer: Transformation. This mechanism relies on competent cells absorbing extracellular DNA released from lysed bacteria in the environment.

Flashcard 15: Identify the donor type: F factor integrated into chromosome and transfers chromosomal genes at high frequency.

Answer: Hfr cell. Integration of F into the chromosome enables high-efficiency transfer of linked bacterial genes during conjugation.

Flashcard 16: Which option best defines bacterial transduction?

Answer: Transfer of bacterial DNA mediated by a bacteriophage. Bacteriophages package and deliver bacterial DNA during infection, enabling gene transfer between hosts.

Flashcard 17: What is an Hfr cell in bacterial conjugation?

Answer: Cell with F factor integrated into the bacterial chromosome. Integration of the F plasmid into the chromosome allows transfer of chromosomal genes during conjugation.

Flashcard 18: What does the F factor encode that enables conjugation?

Answer: Genes for sex pilus formation and DNA transfer (tra genes). These genes facilitate the formation of a conjugation bridge and single-stranded DNA transfer during bacterial mating.

Flashcard 19: What is an F′ (F prime) plasmid?

Answer: F plasmid that excised with adjacent chromosomal genes. Imprecise excision incorporates host DNA into the plasmid, enabling transfer of specific chromosomal genes via conjugation.

Flashcard 20: What enzyme catalyzes movement of a transposon?

Answer: Transposase. Transposase recognizes inverted repeats and catalyzes cut-and-paste or replicative movement of the transposon.

Flashcard 21: What is the term for a plasmid that can transfer itself between bacteria?

Answer: Conjugative plasmid. These plasmids encode transfer genes enabling self-propagation through conjugation between bacterial cells.

Flashcard 22: What is the most common F status of the recipient after Hfr × F− conjugation?

Answer: F− (transfer usually stops before the entire F factor enters). Conjugation bridges often break before the full F factor transfers, preventing the recipient from gaining donor capability.

Flashcard 23: Which option best defines a plasmid in prokaryotes?

Answer: Small circular extrachromosomal dsDNA that replicates independently. Plasmids provide genetic flexibility in prokaryotes by carrying accessory genes that can be horizontally transferred and replicated separately from the chromosome.

Flashcard 24: Which F status is produced when an F plasmid excises incorrectly and carries a host gene into the plasmid?

Answer: F′ (F prime). Aberrant excision merges plasmid and chromosomal DNA, creating a hybrid capable of specialized gene transfer.

Flashcard 25: What is the term for transfer of bacterial DNA via direct cell-to-cell contact?

Answer: Conjugation. This process requires a sex pilus for cell contact and involves rolling-circle replication to transfer single-stranded DNA.