# PromethION 24 Sequencer How the PromethION 24 sequencer reads DNA: nanopores in 24 flow cells read each letter as it passes an electric current, and a tower turns those signals into sequences\. By cosmic\-heron\-269b2d6c Topic: Nature & Biology [Open the interactive Jig](https://ask.jig.com/j/VHwvoekxajnj) ## Transcript ### 1. Meet PromethION 24 This bench holds a machine that reads DNA, the instruction code inside every living thing\. The low box on the left reads samples\. The tall tower beside it does the heavy thinking\. Made by Oxford Nanopore\. Drag anywhere to turn the bench\. ### 2. Two units, true to size Everything here is built to the real measurements\. The Sequencing Unit is 590 mm wide, 190 mm tall and 430 mm deep\. The Compute Unit tower is only 178 mm wide but 440 mm tall and 470 mm deep\. They weigh 23 kg and 26 kg: each about as heavy as a big bag of dog food\. ### 3. Open the lids Samples go in on top\. Three steel lids with smoked windows hinge up to uncover the bays underneath\. Press the button to lift them\. The silver front grilles are air vents, not doors\. ### 4. Twenty\-four flow cells Each bay holds a row of eight flow cells: small cartridges that each take a DNA sample\. Three rows of eight make 24\. Watch a blue light come on for each one\. Every flow cell runs on its own, so samples can start and stop at different times\. ### 5. Reading DNA with electricity Inside each flow cell are thousands of tiny holes called nanopores\. A DNA strand is pulled through a pore, and each of its letters, A, C, G or T, changes the electric current in its own way\. No camera and no light: it listens to electricity\. ### 6. The tower turns signals into letters The sequencer sends its current readings to the Compute Unit\. Powerful graphics processors inside the tower turn the wiggles into DNA letters\. This step is called basecalling\. A full run can produce several terabases: trillions of DNA letters\. ### 7. A whole lab on one bench Two boxes on one bench can read the DNA of plants, animals, viruses and people\. Turn the bench and look around both units\. The two units need a bench about 1\.7 m wide\.