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Gene Therapy quiz

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  • What does the acronym CRISPR stand for?
    CRISPR stands for clusters of regularly interspaced short palindromic repeats.
  • What is the natural function of the CRISPR-Cas system in bacteria?
    The CRISPR-Cas system acts as a defense mechanism against phage infections in bacteria.
  • What are spacers in the context of the CRISPR-Cas system?
    Spacers are small fragments of phage DNA stored in the bacterial chromosome as a record of previous infections.
  • How are spacers incorporated into the bacterial chromosome?
    After a phage infection, degraded phage DNA fragments can be incorporated into the chromosome as spacers.
  • What happens during a subsequent phage infection in a bacterium with the CRISPR-Cas system?
    The bacterium transcribes spacer DNA into RNA, which forms a complex with the Cas enzyme to target and cleave the phage DNA.
  • What role does the Cas enzyme play in the CRISPR-Cas system?
    The Cas enzyme forms a complex with RNA and cleaves the infecting phage DNA to inactivate it.
  • How does the RNA in the Cas complex guide the enzyme?
    The RNA sequence is complementary to the phage DNA, guiding the Cas enzyme to the correct target for cleavage.
  • Why is the CRISPR-Cas system considered adaptive immunity?
    It adapts by storing DNA from previous infections, allowing bacteria to defend against specific phages in the future.
  • How is the CRISPR-Cas system passed to future generations of bacteria?
    Because it is part of the chromosome, the CRISPR system is replicated and inherited by future generations.
  • What is the main purpose of the CRISPR-Cas system in bacteria?
    Its main purpose is to protect bacteria from phage infections by inactivating phage DNA.
  • What happens to phage DNA during the first infection in the CRISPR-Cas system?
    Phage DNA is degraded into fragments, some of which are incorporated as spacers in the chromosome.
  • What is formed when spacer RNA combines with the Cas enzyme?
    A Cas RNA complex is formed, which targets and cleaves phage DNA during subsequent infections.
  • How does the CRISPR-Cas system ensure ongoing defense against specific phages?
    By storing phage DNA as spacers, it allows bacteria to recognize and inactivate the same phage upon reinfection.
  • What type of immunity does the CRISPR-Cas system exemplify?
    It exemplifies active humoral immunity in bacteria.
  • Why is genetic memory important in the CRISPR-Cas system?
    Genetic memory allows bacteria to remember and defend against phages they have previously encountered.