Textbook Question
Radiation is frequently used as part of the treatment of cancer. The radiation works by damaging DNA and components of the cell. Under what circumstances do you think radiation treatment is a good choice to treat cancer?
Ch. 14 - Analysis of Gene Function via Forward Genetics and Reverse Genetics
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch. 1 - The Molecular Basis of Heredity, Variation, and Evolution64
- Ch. 2 - Transmission Genetics144
- Ch. 3 - Cell Division and Chromosome Heredity81
- Ch. 4 - Gene Interaction87
- Ch. 5 - Genetic Linkage and Mapping in Eukaryotes103
- Ch. 6 - Genetic Analysis and Mapping in Bacteria and Bacteriophages73
- Ch. 7 - DNA Structure and Replication71
- Ch. 8 - Molecular Biology of Transcription and RNA Processing79
- Ch. 9 - The Molecular Biology of Translation110
- Ch. 10 - Eukaryotic Chromosome Abnormalities and Molecular Organization100
- Ch. 11 - Gene Mutation, DNA Repair, and Homologous Recombination86
- Ch. 12 - Regulation of Gene Expression in Bacteria and Bacteriophage90
- Ch. 13 - Regulation of Gene Expression in Eukaryotes38
- Ch. 14 - Analysis of Gene Function via Forward Genetics and Reverse Genetics72
- Ch. 15 - Recombinant DNA Technology and Its Applications69
- Ch. 16 - Genomics: Genetics from a Whole-Genome Perspective49
- Ch. 17 - Organelle Inheritance and the Evolution of Organelle Genomes27
- Ch. 18 - Developmental Genetics43
- Ch. 19 - Genetic Analysis of Quantitative Traits66
- Ch. 20 - Population Genetics and Evolution at the Population, Species, and Molecular Levels105
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
All textbooks
Sanders 3rd EditionCh. 14 - Analysis of Gene Function via Forward Genetics and Reverse GeneticsProblem 7
Sanders 3rd EditionCh. 14 - Analysis of Gene Function via Forward Genetics and Reverse GeneticsProblem 7Chapter 14, Problem 7
Diagram the mechanism by which CRISPR–Cas functions in the immune system of bacteria and archaea.
Verified step by step guidance1
Understand the context: CRISPR–Cas is an adaptive immune system in bacteria and archaea that provides defense against invading genetic elements such as viruses (phages) and plasmids. It involves three main stages: adaptation, expression, and interference.
Step 1: Adaptation - When a bacterium is infected by a virus, the CRISPR–Cas system captures a short segment of the viral DNA and incorporates it into the CRISPR array in the bacterial genome. This segment, called a 'spacer,' is stored between repeat sequences in the CRISPR locus.
Step 2: Expression - The CRISPR array is transcribed into a long RNA molecule, which is then processed into smaller CRISPR RNAs (crRNAs). Each crRNA contains a spacer sequence that matches the DNA of a previously encountered virus.
Step 3: Interference - When the same virus infects the bacterium again, the crRNA guides the Cas protein to the matching viral DNA sequence. The Cas protein, which has nuclease activity, binds to the viral DNA and cleaves it, thereby neutralizing the threat.
Diagram the process: To visualize this mechanism, create a diagram with three sections: (1) Adaptation - show viral DNA being integrated into the CRISPR array, (2) Expression - depict the transcription and processing of crRNA, and (3) Interference - illustrate the crRNA-Cas complex targeting and cleaving the viral DNA.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
CRISPR-Cas System
The CRISPR-Cas system is a bacterial and archaeal adaptive immune mechanism that protects against viral infections. It consists of CRISPR sequences, which are short segments of DNA derived from previous viral infections, and Cas proteins that perform various functions, including cutting foreign DNA. This system allows organisms to 'remember' past infections and mount a targeted response upon subsequent encounters with the same virus.
Recommended video:
Guided course
09:28
Genomic Variation
Guide RNA
Guide RNA (gRNA) is a crucial component of the CRISPR-Cas system, serving as a template that directs the Cas proteins to the specific DNA sequence of the invading virus. The gRNA is complementary to the target DNA, ensuring precise binding and cleavage. This specificity is vital for the effectiveness of the immune response, allowing the organism to eliminate only the viral DNA without affecting its own genetic material.
Recommended video:
DNA Cleavage
DNA cleavage is the process by which the Cas proteins, guided by the gRNA, cut the DNA of invading viruses. This action effectively neutralizes the threat by preventing the virus from replicating and expressing its genes. The ability to cleave DNA at specific sites is what makes the CRISPR-Cas system a powerful tool not only for bacterial immunity but also for genetic engineering applications in various organisms.
Recommended video:
Guided course
01:45DNA Proofreading
Related Practice
Textbook Question
Radiation is frequently used as part of the treatment of cancer. The radiation works by damaging DNA and components of the cell. Is there a risk of damage to noncancer cells?
Textbook Question
Radiation is frequently used as part of the treatment of cancer. The radiation works by damaging DNA and components of the cell. How can radiation treatment control or cure cancer?
Textbook Question
Why do most cancers require the mutation of multiple genes?
Textbook Question
Based on what you read in this chapter, Can a tumor arise from a single mutated cell? Are all the cells in a tumor identical?
Textbook Question
Describe how CRISPR–Cas has been modified to create a genome-editing tool.