Year 10 Science · Unit 1 · Lesson 9

Gene Editing and CRISPR

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Learning Goals

Trace the cause-and-effect chain from sickle cell mutation to CRISPR cure.
Compare CRISPR gene therapy against viral vector gene therapy across four features.
Apply understanding of somatic vs germline editing to evaluate risk and ethics.

Warm Up

Because… chain

Fill in the missing effects. Each step traces the CRISPR treatment for sickle cell disease from diagnosis to cure.

A patient has sickle cell disease caused by a mutation in the haemoglobin gene

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Scientists design a guide RNA that matches the exact location of the mutation

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Cas9 cuts both strands of DNA at the target site in the patient's blood stem cells

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A repair template with the correct DNA sequence is introduced to guide cell repair

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Edited blood stem cells are returned to the patient's bloodstream

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Why this is somatic (not germline) editing, and what that means for inheritance:

Your Turn

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

Show What You Know

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.

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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.

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Wrap Up

In one sentence, explain why off-target effects are a significant concern in CRISPR therapy.