Textbook Question
Why are the recombinants produced from an Hfr x F⁻ cross rarely, if ever, F⁺?
Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages
Klug12th EditionConcepts of Genetics ISBN: 9780135564776
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Table of contents
- Ch. 1 - Introduction to Genetics17
- Ch. 2 - Mitosis and Meiosis36
- Ch. 3 - Mendelian Genetics51
- Ch. 4 - Extensions of Mendelian Genetics74
- Ch. 5 - Chromosome Mapping in Eukaryotes51
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages46
- Ch. 7 - Sex Determination and Sex Chromosomes33
- Ch. 8 - Chromosome Mutations: Variation in Number and Arrangement40
- Ch. 9 - Extranuclear Inheritance31
- Ch. 10 - DNA Structure and Analysis43
- Ch. 11 - DNA Replication and Recombination44
- Ch. 12 - DNA Organization in Chromosomes30
- Ch. 13 - The Genetic Code and Transcription54
- Ch. 14 - Translation and Proteins47
- Ch. 15 - Gene Mutation, DNA Repair, and Transposition41
- Ch. 16 - Regulation of Gene Expression in Bacteria29
- Ch. 17 - Transcriptional Regulation in Eukaryotes41
- Ch. 18 - Post-transcriptional Regulation in Eukaryotes33
- Ch. 19 - Epigenetics33
- Ch. 20 - Recombinant DNA Technology44
- Ch. 21 - Genomic Analysis36
- Ch. 22 - Applications of Genetic Engineering and Biotechnology36
- Ch. 23 - Developmental Genetics37
- Ch. 24 - Cancer Genetics34
- Ch. 25 - Quantitative Genetics and Multifactorial Traits54
- Ch. 26 - Population and Evolutionary Genetics45
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Klug 12th EditionCh. 6 - Genetic Analysis and Mapping in Bacteria and BacteriophagesProblem 8
Klug 12th EditionCh. 6 - Genetic Analysis and Mapping in Bacteria and BacteriophagesProblem 8Chapter 6, Problem 8
Describe the origin of F' bacteria and merozygotes.
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Understand that F' (F prime) bacteria originate from an F factor (fertility factor) that has excised incorrectly from the bacterial chromosome, capturing some adjacent chromosomal genes along with the F plasmid.
Recognize that this excision event creates an F' plasmid, which carries both the fertility genes and some bacterial chromosomal genes, allowing the F' bacteria to transfer these chromosomal genes during conjugation.
Define merozygotes as partial diploid bacterial cells formed when an F' bacterium conjugates with an F- bacterium, transferring the F' plasmid and thus introducing an extra copy of certain chromosomal genes into the recipient.
Note that merozygotes contain one copy of the chromosomal genes on the bacterial chromosome and an additional copy on the F' plasmid, which can be used to study gene function and complementation.
Summarize that the origin of F' bacteria is due to aberrant excision of the F factor capturing chromosomal genes, and merozygotes result from conjugation involving F' bacteria, leading to partial diploidy.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
F' (F-prime) Bacteria
F' bacteria are formed when an F plasmid excises incorrectly from the bacterial chromosome, carrying with it some chromosomal genes. This results in a plasmid that contains both F factor genes and additional bacterial genes, enabling the transfer of these genes during conjugation.
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08:52
F Factor and Hfr
Merozygotes
Merozygotes are partial diploid bacterial cells formed when an F' plasmid transfers chromosomal genes to a recipient cell. They contain two copies of certain genes—one on the chromosome and one on the F' plasmid—allowing the study of gene function and complementation.
Conjugation and Plasmid Excision
Conjugation is the process by which genetic material is transferred between bacteria via direct contact. During this process, the F plasmid can excise from the chromosome, sometimes inaccurately, leading to the formation of F' plasmids that carry extra chromosomal genes.
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02:19R Plasmid
Related Practice
Textbook Question
Describe the basis for chromosome mapping in the Hfr x F⁻ crosses.
Textbook Question
In general, when recombination experiments are conducted with bacteria, participating bacteria are mixed in complete medium, then transferred to a minimal growth medium. Why isn't the protocol reversed: minimal medium first, complete medium second?
Textbook Question
In a transformation experiment, donor DNA was obtained from a prototroph bacterial strain (a⁺b⁺c⁺), and the recipient was a triple auxotroph (a⁻b⁻c⁻). What general conclusions can you draw about the linkage relationships among the three genes from the following transformant classes that were recovered?
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Textbook Question
Describe the role of heteroduplex formation during transformation.
Textbook Question
Explain the observations that led Zinder and Lederberg to conclude that the prototrophs recovered in their transduction experiments were not the result of F⁺ mediated conjugation.