What sits inside the editing window and causes bystander edits?

• Only the target base ever
• Several neighbouring positions the deaminase can reach
• The whole chromosome at once

A cytosine base editor is aimed at a C. What change does it install?

• C to T
• C to A
• C to G

Prime editors write new sequence from a template carried on the guide.

Circle one:   True   False

Your target A has another A beside it in the window. What is the best design move?

• Ignore the neighbour and hope
• Use a plain nuclease cut instead for precision
• Shift the guide so only the target of the right kind sits in the window

You need a C to A change (a transversion). Which tool fits?

• A cytosine base editor
• An adenine base editor
• Prime editing

Rank these by precision for a single-letter fix, from crudest to cleanest.

• Prime editing, then base editing, then plain cut
• Plain cut, then base editing, then prime editing
• Base editing, then plain cut, then prime editing

A plain nuclease cut is the most precise way to install a single-letter change.

Circle one:   True   False

A base edit keeps vanishing: sequencing shows the original letter returns. What most likely erased it?

• The cell's repair pathways rejected the fresh change
• The guide was too specific
• The sequencing machine invented the original