Label the following parts of the CRISPR-Cas9 system: A – Target DNA strand B – PAM sequence C – Cas9 protein D – Single-guide RNA Part 2 (1 pt) In CRISPR-Cas9, is used to replace a mutated DNA sequence that leads to genetic disease with an alternative DNA sequence that does not contain the mutation. This method of DNA repair can be used to produce a . There are many applications of CRISPR-Cas9, and if a researcher needed to find the location of a particular gene on a chromosome using light microscopy, a(n) would be useful.
The Correct Answer and Explanation is:
Part 1: Labeling the CRISPR-Cas9 System
- A – Target DNA Strand: This is the DNA strand that contains the sequence to be edited. It is the portion of the genome that will be cut by the Cas9 protein.
- B – PAM Sequence: The Protospacer Adjacent Motif (PAM) is a short DNA sequence that is essential for the Cas9 protein to recognize and cut the target DNA. It usually follows the target DNA sequence and plays a crucial role in the specificity of the Cas9 enzyme.
- C – Cas9 Protein: This is the enzyme that cuts the DNA at a specific location. The Cas9 protein is guided by the single-guide RNA (sgRNA) to the target DNA, where it creates a double-strand break, leading to DNA repair processes.
- D – Single-guide RNA: The sgRNA is a synthetic RNA molecule that directs the Cas9 protein to the precise location on the target DNA. It consists of two parts: one that binds to the target DNA and another that helps guide the Cas9 protein to the correct spot.
Part 2: Application of CRISPR-Cas9 for Genetic Disease
In CRISPR-Cas9, gene editing is used to replace a mutated DNA sequence that leads to genetic disease with an alternative DNA sequence that does not contain the mutation. This method of DNA repair can be used to produce a corrected gene. By introducing a correctly functioning version of the gene, CRISPR can potentially cure genetic diseases at their source.
Finding Gene Location Using Light Microscopy
If a researcher needed to find the location of a particular gene on a chromosome using light microscopy, a fluorescently-labeled probe would be useful. This probe is typically a piece of DNA that binds specifically to the target gene, and it is labeled with a fluorescent tag. When illuminated with a specific wavelength of light, the probe will fluoresce, allowing the researcher to visually locate the gene under the microscope.
Explanation:
The CRISPR-Cas9 system is a groundbreaking method for gene editing, allowing precise changes to DNA. The process works by using the Cas9 protein, which is guided by the single-guide RNA (sgRNA) to a specific location on the target DNA. The PAM sequence ensures that the Cas9 protein cuts the DNA in the correct region. Once the DNA is cut, the cell’s repair mechanisms take over, which can be harnessed to correct mutations. This technology has vast applications, from treating genetic diseases to creating genetically modified organisms. The ability to target specific genes is further enhanced by using tools like fluorescent probes for gene localization in research.
