Which of the following organisms would be the most difficult to use when performing a genetic screen?

• A. Yeast
• B. E. coli
• C. Zebrafish
• D. Mice

Answer: (D)

Verified step by step guidance

1. Understand what a genetic screen is: A genetic screen is a technique used to identify and select individuals who possess a phenotype of interest in a mutagenized population.
2. Consider the reproductive cycle and generation time: Organisms with shorter generation times and larger numbers of offspring are generally more suitable for genetic screens because they allow for quicker and more extensive analysis.
3. Evaluate the complexity of the organism's genome: Simpler organisms with smaller genomes are easier to manipulate genetically, making them more suitable for genetic screens.
4. Assess the ethical and logistical considerations: Larger and more complex organisms, such as mice, often have more ethical and logistical challenges associated with their use in genetic screens.
5. Compare the organisms: Yeast and E. coli are single-celled organisms with short generation times and simple genomes, making them ideal for genetic screens. Zebrafish, while more complex, still have relatively short generation times and are used in genetic studies. Mice, however, have longer generation times, more complex care requirements, and ethical considerations, making them the most difficult to use for genetic screens.