Year 10 Science · Unit 1 · Lesson 9
Apply Worksheet
Learning Goals
Because… chain
Fill in the missing effects in this hypothetical experimental approach. It models direct correction of the sickle-causing variant in HBB using CRISPR and a repair template; it is not the mechanism of approved Casgevy, which edits a BCL11A enhancer to increase fetal haemoglobin. Direct HBB correction has been studied in laboratory cells, but this worksheet does not describe an approved treatment. See a primary study of this experimental approach.
Why this is somatic (not germline) editing, and what that means for inheritance:
Compare two
Complete the table to compare gene therapy delivered by viral vector with CRISPR-Cas9 gene therapy.
| Feature | Viral Vector Gene Therapy | CRISPR-Cas9 Gene Therapy |
|---|---|---|
| How the change is made to the cell | ||
| Precision, does it target a specific DNA location? | ||
| Risk of germline changes if used in adults | ||
| Main ethical concern | ||
| One real approved use or clinical trial example |
1. Scientists at the Children's Medical Research Institute in Sydney are using CRISPR to study muscular dystrophy. They are editing patient cells grown in a lab, not editing cells inside the patient's body. Explain why this approach is currently considered lower-risk than delivering CRISPR directly into a living patient.
2. Colossal Biosciences is using CRISPR to edit thylacine genes into living marsupial cells, aiming to bring back the Tasmanian tiger (extinct since 1936). Identify one scientific challenge and one ethical concern with this de-extinction project.
Wrap Up
In one sentence, explain why off-target effects are a significant concern in CRISPR therapy.