Here's an example of what's due today

Plasmids and enzymes

Wed, Dec 2, 2026 · Week 15 · Genetics of Disease (Medical Interventions)

Today's goal: Explain how plasmids, restriction enzymes, and ligase work together to build recombinant DNA.

Learn first

What a finished product looks like

This is a model of the work you should turn in today. Use it to check your own: match the structure and the level of detail, do not copy it. Your data and wording should be your own.

Labeled cloning-tools diagram

Completes: Completes the cloning-tools task: a labeled diagram showing a restriction enzyme cutting a plasmid and a gene at matching sites, sticky-end base pairing, and ligase sealing the gene into the plasmid to form recombinant DNA.

Definitions, in my own words:

Plasmid: a small circular piece of DNA in bacteria that can carry an extra gene; it works as the vehicle for the gene I want to insert.
Restriction enzyme: molecular scissors that recognize a short palindromic sequence and cut both DNA strands there, leaving uneven 'sticky ends.'
Ligase: molecular glue that seals the cut backbone after the gene is in place.

Diagram, in steps:

1. The same restriction enzyme cuts both the plasmid and the target gene at matching recognition sites, so both have the same sticky ends.

2. The sticky ends are complementary single-stranded overhangs, so the gene's overhang base-pairs with the matching overhang on the open plasmid, lining the gene up in the right spot.

3. Ligase seals the phosphodiester backbone, locking the gene into the plasmid to form one recombinant DNA molecule.

Why sticky ends help: because the overhangs only base-pair with a matching cut, the gene snaps into the correct position and orientation instead of joining randomly.

A cut plasmid and a separate gene fragment combine, with ligase forming a single recombinant DNA circle carrying the gene.

Also due today: Attach your labeled cloning-tools diagram to your PLTW tracker and submit it to the course shell.

Check yourself

WebXam problem for today's skill

One exam-style question that uses exactly what you practiced today. Try it before you reveal the answer, then read why each choice is right or wrong.

WebXam-style domain: Bio-Molecular TechnologySelf-check skill: Explaining how restriction enzymes, sticky ends, and ligase build recombinant DNA

To insert a gene into a plasmid, a technician cuts both the plasmid and the gene with the same restriction enzyme. Why does using the same enzyme on both help the gene insert in the right place?

Tap an answer to see the full explanation. Nothing is recorded or graded.

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