Recombinant DNA, CRISPR, and Genetic Engineering
Engineering Genomes and Constructs
Recombinant DNA
Recombinant DNA technology combines DNA from different sources using restriction enzymes, ligases, vectors, and host cells. It enables protein production, reporter assays, pathway engineering, and therapeutic development.
CRISPR-Cas Systems
CRISPR-Cas editing uses a guide RNA to target a complementary DNA sequence and a nuclease or effector protein to make a cut or change gene expression. Outcomes depend on repair pathway choice or programmable editing chemistry.
Why CRISPR Is Powerful
A short guide RNA can direct a molecular tool to a nearly chosen DNA sequence, making editing highly adaptable and scalable.
Genome Editing Outcomes
| Approach | Typical Result |
|---|---|
| Non-homologous end joining | Often creates insertions or deletions |
| Homology-directed repair | Can introduce precise changes |
| CRISPR interference | Reduces transcription without cutting DNA |
| Base editing | Changes one base to another without double-strand break |
What does guide RNA do in CRISPR editing?
The guide RNA provides sequence specificity.
Correct answer: Directs the nuclease to a complementary DNA target
Why might non-homologous end joining be useful in gene knockout experiments?
Frameshifting can abolish gene function.
Correct answer: It often creates small insertions or deletions that disrupt the reading frame.
Basic Recombinant DNA Workflow
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1
Step 1: Choose a gene or DNA fragment of interest.
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2
Step 2: Insert it into a vector using compatible ends or assembly chemistry.
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3
Step 3: Deliver the vector into host cells.
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4
Step 4: Select or screen for successful transformants.
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5
Step 5: Verify the construct by sequencing or expression analysis.
Editing Strategies
Knockout
- Disrupts a gene
- Useful for loss-of-function studies
Knock-in
- Introduces a defined sequence
- Useful for tagging or correcting genes
Which outcome is most associated with homology-directed repair?
HDR can make targeted, precise edits if a donor template is available.
Correct answer: A precise sequence insertion or correction
Name one application of recombinant DNA in biotechnology.
Engineered organisms can express medically useful proteins at scale.
Correct answer: Recombinant protein production, such as insulin manufacturing.