Chapter 9: DNA Fingerprinting, CRISPR-Cas9, and PCR - Practice Flashcards

A set of Q&A flashcards covering DNA fingerprinting, CRISPR-Cas9 basics and ethics, PCR mechanics, and precision medicine as discussed in the notes.

What is the basic idea behind DNA fingerprinting using gel electrophoresis?

DNA is cut into fragments of different sizes; gel electrophoresis separates these fragments, producing a banding pattern unique to individuals because DNA sequences vary.

What does CRISPR stand for and what is Cas9's role in CRISPR-Cas9 gene editing?

CRISPR stands for clustered regularly interspaced short palindromic repeats; Cas9 is a programmable nuclease that creates a double-stranded break in DNA at a location guided by RNA.

Where did the CRISPR-Cas9 technology originate conceptually?

From basic research into how bacteria defend against viruses; bacteria use CRISPR to record viral DNA and Cas9 to cut invading viral DNA.

What is the function of guide RNA in the CRISPR-Cas9 system?

Guide RNA contains a sequence that matches a target DNA site and directs the Cas9 enzyme to that site for cutting.

What happens after Cas9 introduces a double-stranded break in DNA?

Cells repair the break, which can disrupt the gene or incorporate a new DNA sequence, enabling precise genome edits.

What are key ethical concerns surrounding the use of CRISPR in humans?

Embryo/germline editing and heritable changes, potential off-target effects, unequal access, enhancements versus disease treatment, and the need for broad societal discussion and safeguards.

What evidence suggests that clinical CRISPR applications are being pursued?

Clinical trials in humans exist (e.g., in India); progress in animals and human cells; ongoing development and interest from biotech startups, with attention to safety and delivery challenges.

How does PCR work at a high level?

PCR amplifies a specific DNA region through repeated cycles of denaturation, primer annealing, and DNA synthesis (extension) by DNA polymerase, producing billions of copies.

What determines which DNA region is amplified in a PCR reaction?

The primers—short DNA sequences—bind to complementary regions flanking the target sequence, thereby defining what gets amplified.

How many cycles are typical in a PCR run and how much can one starting molecule be amplified?

Typically about 30 cycles, which can yield up to ~1,000,000,000 copies of the target sequence from a single starting molecule.

What does NAAT stand for and how is it related to PCR?

NAAT stands for nucleic acid amplification test; it generally refers to PCR-based methods used to detect pathogens by amplifying their DNA.

What is precision medicine?

An approach to tailor medical treatment to the individual using genetic information and other health data, aiming to guide therapy to each person (not fully realized yet).

What is the All of Us program?

A U.S. initiative to collect data from about one million volunteers to sequence genomes and study how genetics and environment influence health care.

Where are initial clinical CRISPR applications likely to be easier to deliver, and why?

In blood cells, because delivery to these cells is typically easier than to solid tissues.

What analogy is often used to describe CRISPR genome editing, and what does it imply?

CRISPR is like software for the genome; it is programmable via guide RNA to make precise edits at chosen DNA sites.

What is a major technical challenge associated with CRISPR that researchers are addressing?

Off-target effects and delivery methods; ensuring specificity and safe, effective delivery to target tissues.

Which organisms were mentioned as models for CRISPR research and potential therapies?

Mice, monkeys, and humans (with early human embryo work and HIV-related edits discussed in the notes).

What are the core components of the CRISPR-Cas9 editing mechanism described in the notes?

A Cas9 protein and a guide RNA that directs Cas9 to a matching DNA sequence to create a double-stranded cut.

What essential difference exists between prokaryotes and eukaryotes highlighted in the notes?

Prokaryotes lack a nucleus and membrane-bound organelles, while eukaryotes have a nucleus and more complex cellular structures.