Chapter 16. Chapter 16: Mutation Analysis in Neurospora

Introduction

Unpacking the Problem
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You must read each slide, and complete any questions on the slide, in sequence.

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

wVRfo9JQtNe3wJ4B8j1l/VEmgxTgPcYUasd330Hyoy164AAuCgeryf+BvkGKt1JYMvjTVdJf2xody+eW0n0RBjGQkNj7USabMgddb9eOxQS8vXtc26NAEbwJDDaFh9db0Yc4+o2CgR0A24rji7R6MjkypgTWRSwXZupF42rLU6VKUA5joG4J50nRaBpPkXkwbY5RMWkA765o9DociEopA/IIofoZdVNPq1uxV7FNcZE04b+Uf1pX6C3IzTm+XoEYF3stjtle4KJId8IcQWNGE21xxPVWd7Q/3o31AnW9InVoExeW6g6mSKdlw16hfeqYzg2ZOhAYJWX0R0oZLIyunbo6O6LlD978pMaOxOI4lij8Tmqdc/UGaZImocZf/53eR3ULC0HaDPYdRFwRbDyZJUI73f/ZwVAPggT5a3nbKGrHl2pQ4WFTdxw1a4QZiVw+o2PEklXPy9eiU1ReznUIRhooYNeZ+dVz4XAgwzdkurHaip665ryoyHxCf9pXnTiIjMINXfeCpIIhwIThKeHJUYf8plHWkSJK+soaFgQthhV7yPMBK+u5SJxmFDrCkJX00ldwIDxuYQA1VZALmFYTTxvq1EmlTK5YNnAb4hIg4qdsL6GAkLrRzCkVx7PsCJEbUqj+movWdaB6/qSpm2+QtdPElXC7qeVgEeJ1bnR/1A+cPrRVpWTNa+VjG63l9UOcTbmiEIS5pLu3ESvoioPxk0whq7XVCqzvqSvppupkspZb9MQAjcqhIVOUGAVML52v1ASuD3iMG+4ZNGDJHferGgGQs3TqhxlKH4zHYwinIlJBkebtsqFK4HU9LW6d9h2UC68COerm4Md0B5GcHPiRd4rbYjhb/+VcrK2iqQ==
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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1

You are using nitrosoguanidine to "revert" mutant nic-2 (nicotinamide-requiring) alleles in Neurospora. You treat cells, plate them on a medium without nicotinamide, and look for prototrophic colonies. You obtain the following results from two mutant alleles.

a. With nic-2 allele 1, you obtain no prototrophs at all.

b. With nic-2 allele 2, you obtain three prototrophic colonies, A, B, and C, and you cross each separately with a wild-type strain of Neurospora. From the cross prototroph A × wild type, you obtain 100 progeny, all of which are prototrophic. From the cross prototroph B × wild type, you obtain 100 progeny, of which 78 are prototrophic and 22 are nicotinamide requiring. From the cross prototroph C × wild type, you obtain 1000 progeny, of which 996 are prototrophic and 4 are nicotinamide requiring.

Explain these results at the molecular level.

Unpack the Problem: Break this problem into several parts and arrive at a solution using this guided, step-by-step approach.

  • Part A (steps 1-9): Secure a basic understanding of the experimental protocol.
  • Part B (steps 10 and 11): Explain the results of mutagenizing Neurospora nic-2 allele 1 cells.
  • Part C (steps 12-14): Assemble background information for understanding the nic-2 allele 2 results.
  • Part D (steps 15-17): Explain the results of mutagenizing Neurospora nic-2 allele 2 cells.

Question

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
1

Conclusion

Inducing mutations is a powerful tool that geneticists use for generating phenotypic variants. These variants can then be studied to identify the mutated genes as well as the gene products that the wild-type genes encode. These studies can be extended, in some cases, to unravel biochemical pathways or identify protein interactions. The creation of revertants can be used to identify additional genes (e.g., suppressors) and their gene products.