Textbook Question
Why are the recombinants produced from an Hfr x F⁻ cross rarely, if ever, F⁺?
Ch. 8 - Genetic Analysis and Mapping in Bacteria and Bacteriophages
Klug10th EditionEssentials of GeneticsISBN: 9780135588789
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Table of contents
- Ch. 1 - Introduction to Genetics16
- Ch. 2 - Mitosis and Meiosis28
- Ch. 3 - Mendelian Genetics37
- Ch. 4 - Modification of Mendelian Ratios53
- Ch. 5 - Sex Determination and Sex Chromosomes32
- Ch. 6 - Chromosome Mutations: Variation in Number and Arrangement37
- Ch. 7 - Linkage and Chromosome Mapping in Eukaryotes36
- Ch. 8 - Genetic Analysis and Mapping in Bacteria and Bacteriophages24
- Ch. 9 - DNA Structure and Analysis38
- Ch. 10 - DNA Replication29
- Ch. 11 - Chromosome Structure and DNA Sequence Organization22
- Ch. 12 - The Genetic Code and Transcription36
- Ch. 13 - Translation and Proteins27
- Ch. 14 - Gene Mutation, DNA Repair, and Transposition34
- Ch. 15 - Regulation of Gene Expression in Bacteria22
- Ch. 16 - Regulation of Gene Expression in Eukaryotes37
- Ch. 17 - Recombinant DNA Technology27
- Ch. 18 - Genomics, Bioinformatics, and Proteomics30
- Ch. 19 - The Genetics of Cancer21
- Ch. 20 - Quantitative Genetics and Multifactorial Traits37
- Ch. 21 - Population and Evolutionary Genetics45
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Klug 10th EditionCh. 8 - Genetic Analysis and Mapping in Bacteria and BacteriophagesProblem 8
Klug 10th EditionCh. 8 - Genetic Analysis and Mapping in Bacteria and BacteriophagesProblem 8Chapter 8, 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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Related Practice
Textbook Question
List all major differences between:
(a) The F⁺ x F⁻ and the Hfr x F⁻ bacterial crosses
(b) The F⁺, F⁻, Hfr, and F' bacteria.
Textbook Question
Describe the basis for chromosome mapping in the Hfr x F⁻ crosses.
Textbook Question
The bacteriophage genome consists of many genes encoding proteins that make up the head, collar, tail, and tail fibers. When these genes are transcribed following phage infection, how are these proteins synthesized, since the phage genome lacks genes essential to ribosome structure?