Question

In a genomics-based search for mutations that caused a patient's cancer, which of the following would provide the most informative comparison with the cancer cell? a. the DNA sequence of a cell from a mouse with a similar cancer b. the DNA sequence of a noncancerous cell from another person c. the DNA sequence of a noncancerous cell from the patient d. the DNA sequence of another cancer cell from the patient

Short answer

The most informative comparison for identifying the mutations causing a patient's cancer is option c, comparing the cancer cell with the DNA sequence of a noncancerous cell from the patient. This method eliminates genetic differences unrelated to the cancer, making it easier to identify the specific mutations involved in cancer development.

Step-by-step solution

Understanding each of the provided options#

In this exercise, we have four options to choose from: a. the DNA sequence of a cell from a mouse with a similar cancer b. the DNA sequence of a noncancerous cell from another person c. the DNA sequence of a noncancerous cell from the patient d. the DNA sequence of another cancer cell from the patient Let us analyze each of these options and understand their advantages and disadvantages when it comes to identifying mutations causing the patient's cancer.

Comparing a mouse cancer cell (option a)#

In this option, we are comparing the patient's cancer cell with the DNA sequence of a cell from a mouse with a similar cancer. Although there could be similarities between the mutations causing the cancer in both the mouse and the patient, there will also be many genetic differences between the two species, making it challenging to pinpoint the precise cause of the patient's cancer. Therefore, this option is less informative for identifying the mutations causing the patient's cancer.

Comparing a noncancerous cell from another person (option b)#

In option b, we are comparing the patient's cancer cell with the DNA sequence of a noncancerous cell from another person. While both human cells will have more similarities than the mouse option, there will still be genetic differences between the individuals unrelated to the cancer, making it difficult to identify the specific mutations causing the patient's cancer.

Comparing a noncancerous cell from the patient (option c)#

Option c involves comparing the patient's cancer cell with the DNA sequence of a noncancerous cell from the patient. By using a sample from the same individual, we can eliminate most genetic differences unrelated to the cancer, making it easier to identify the specific mutations involved in the patient's cancer development.

Comparing another cancer cell from the patient (option d)#

In option d, we are comparing the patient's cancer cell with the DNA sequence of another cancer cell from the same patient. Although these two cells may have more similarities than the previous options, it does not consider the patient's original, noncancerous DNA sequence, making it more challenging to pinpoint the precise mutations causing the cancer.

Determining the most informative comparison#

Based on the analysis of the four options, option c (comparing the patient's cancer cell with the DNA sequence of a noncancerous cell from the patient) provides the most informative comparison for identifying the mutations causing the patient's cancer. This option allows for the elimination of genetic differences unrelated to the cancer, making it easier to identify the specific mutations involved in cancer development.

Key concepts

Mutation Identification

Understanding the process of mutation identification is crucial in cancer genomics. Mutations are changes in the DNA sequence that can lead to cancer. Identifying these mutations helps researchers and medical professionals understand the genetics behind a patient's cancer.
To identify mutations, it's important to compare the DNA of cancerous cells with DNA that hasn't undergone malignant transformation. This allows for the identification of mutations specific to cancer cells.

There are several methods to achieve mutation identification:

• Comparing the DNA of cancerous cells with normal, healthy cells from the same patient. This is the most effective method because it eliminates irrelevant genetic variations caused by individual differences.
• Using advanced DNA sequencing techniques to pinpoint abnormal variations in cancer genomes.
• Analyzing genome-wide data to detect both common and rare mutations.

Mutation identification is a vital step in understanding how cancers develop and for developing targeted therapies. Properly identified mutations help tailor more effective treatment plans based on the underlying genetic causes of a patient's cancer.

DNA Sequencing

DNA sequencing is the technique used to determine the exact sequence of nucleotide bases in a DNA molecule. This method is essential for exploring the genetic changes leading to cancer. When it comes to cancer genomics, sequencing helps in examining how cancer cells differ from normal ones at a genetic level.

There are several types of DNA sequencing methods:

• Sanger Sequencing: The first sequencing method widely used and still serves as a benchmark for accuracy.
• Next-Generation Sequencing (NGS): This is a high-throughput sequencing technology that allows for rapid sequencing of large amounts of DNA, making it highly suitable for comprehensive cancer genomic studies.
• Whole Genome Sequencing: Involves sequencing the entire genomic DNA, providing a detailed view of all potential mutations.
• Targeted Sequencing: Focuses on specific genes known to be associated with cancer, allowing for a focused analysis.

DNA sequencing is a powerful tool in cancer research as it provides detailed insights into specific genetic changes associated with cancer. With these insights, researchers can better understand cancer evolution and develop precise interventions.

Noncancerous Cell Comparison

A comparison of noncancerous cells with cancerous ones is pivotal in identifying cancer-specific mutations. By analyzing cells from the same patient, it's possible to eliminate background genetic differences unrelated to cancer. This ensures that any identified mutations are more likely to be responsible for the cancer's development and progression.

The process involves:

• Extracting DNA: Cells are gathered both from cancerous and noncancerous sources.
• Sequencing and Comparison: Both DNA samples are sequenced. Comparing these sequences helps in spotting mutations that are present in cancerous cells but absent in the noncancerous ones.
• Focusing on Relevance: By eliminating unrelated genetic variations, researchers are left with a list of mutations that are more likely to play a role in the cancer. This helps in narrowing down potential genetic targets for treatments.

Noncancerous cell comparison is a fundamental approach in cancer genomics, as it provides a clear baseline to identify meaningful genetic changes that aid in both understanding and combatting cancer.