Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

5. Genetics of Bacteria and Viruses

Bacteriophage Genetics

Genetics

5. Genetics of Bacteria and Viruses

Bacteriophage Genetics

Previous problemNext problem

2:05 minutes

Problem 22a

Textbook Question

In studies of recombination between mutants 1 and 2 from Problem 21, the results shown in the following table were obtained.

Calculate the recombination frequency.

Verified step by step guidance

Understand the problem: Recombination frequency is calculated as the number of recombinant plaques divided by the total number of plaques. Recombinant plaques are those that can grow on E. coli K12 (indicated by the '+' phenotype).

Identify the data provided: From the table, the number of plaques on E. coli K12 (recombinants) is 8, and the dilution factor for this strain is 10⁻². For E. coli B, the number of plaques is 4, and the dilution factor is 10⁻⁷.

Calculate the total number of plaques for each strain by multiplying the observed plaques by the dilution factor. For example, for E. coli K12, the total plaques = observed plaques × dilution factor.

Determine the total number of plaques by summing the plaques from both strains (E. coli B and E. coli K12).

Calculate the recombination frequency using the formula:

\frac{Number of recombinant plaques}{Total number of plaques}

. This will give the recombination frequency as a proportion.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above

Video duration:

Play a video:

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Recombination Frequency

Recombination frequency is a measure of the likelihood that two genes will be separated during meiosis due to crossing over. It is calculated as the number of recombinant offspring divided by the total number of offspring, often expressed as a percentage. This frequency helps in mapping the distance between genes on a chromosome, with higher frequencies indicating genes that are further apart.

Mutants and Phenotypes

In genetics, mutants refer to organisms that have undergone a change in their DNA sequence, resulting in a new phenotype, or observable characteristic. The phenotypes can be categorized as wild-type (normal) or mutant types, which can be used to study genetic variations and inheritance patterns. Understanding the phenotypes of the strains involved is crucial for interpreting recombination results.

Plaque Assay

A plaque assay is a laboratory technique used to measure the number of viral particles or bacterial cells in a sample by observing the formation of plaques, which are clear zones on a bacterial lawn caused by viral lysis. In the context of the question, the number of plaques formed by different strains indicates the effectiveness of recombination and the presence of specific phenotypes, which are essential for calculating recombination frequency.

Watch next

Master Plaques and Experiments with a bite sized video explanation from Kylia

Start learning

Related Videos

Related Practice

Textbook Question

An attribute of growth behavior of eight bacteriophage mutants (1 to 8) is investigated in experiments that establish coinfection by pairs of mutants. The experiments determine whether the mutants complement one another (+) or fail to complement (-). These eight mutants are known to result from point mutation. The results of the complementation tests are shown below.

Identify the mutants of each gene.

407

views

Textbook Question

How many genes are represented by these mutations?

517

views

Textbook Question

In studies of recombination between mutants 1 and 2 from Problem 21, the results shown in the following table were obtained.Strain Dilution Plaques PhenotypesE. coli B 10⁻⁷ 4 rE. coli K12 10⁻² 8 +Mutant 7 (Problem 21) failed to complement any of the other mutants (1–6). Define the nature of mutant 7.

410

views

Textbook Question

In studies of recombination between mutants 1 and 2 from Problem 21, the results shown in the following table were obtained.

When mutant 6 was tested for recombination with mutant 1, the data were the same as those shown above for strain B, but not for K12. The researcher lost the K12 data but remembered that recombination was ten times more frequent than when mutants 1 and 2 were tested. What were the lost values (dilution and plaque numbers)?

367

views

Textbook Question

Define the term genetic complementation.

Describe how the term applies to an experiment in which two lysis-defective bacteriophages are able to coinfect a bacterial cell and produce lysis.

523

views

Textbook Question

A plaque assay is performed beginning with 1 mL of a solution containing bacteriophages. This solution is serially diluted three times by combining 0.1 mL of each sequential dilution with 9.9 mL of liquid medium. Then 0.1 mL of the final dilution is plated in the plaque assay and yields 17 plaques. What is the initial density of bacteriophages in the original 1 mL?

767

views

Multiple Choice

A plaque assay studies viruses through what measurement?

A mixed infection of two bacteriophage strains is often used for what purpose?

409

views

Show more practices