EcoRI cut, sticky ends & recombinant DNAEcoRI द्वारा काटना, चिपचिपे सिरे व पुनर्योगज DNA

NCERT Fig 9.1 · Class 12 Biology · Chapter 9 · interactive diagram

Parts and their functions

• Vector DNA (संवाहक DNA) — The carrier DNA (e.g. a plasmid) that will take the foreign gene into the host.
• Recognition site — palindrome GAATTC (पहचान स्थल — पैलिंड्रोम GAATTC) — EcoRI recognises this 6-bp palindrome: read 5′→3′ it is GAATTC on BOTH strands.
• Cut between G and A (G और A के बीच कटाव) — EcoRI cuts each strand between G and A — a little away from the centre of the palindrome but between the same two bases on the opposite strands. The two cuts are staggered.
• Sticky ends (AATT overhangs) (चिपचिपे सिरे (AATT)) — Single-stranded overhanging stretches left at each end. They form hydrogen bonds with complementary cut ends, so pieces cut by the same enzyme stick together.
• Foreign (alien) DNA (बाहरी (विजातीय) DNA) — The DNA with the gene of interest, cut with the SAME restriction enzyme so its sticky ends match the vector.
• DNA ligase (DNA लाइगेज) — The "molecular glue" — joins the sugar-phosphate backbones of the paired ends.
• Recombinant DNA (पुनर्योगज DNA) — Vector + foreign DNA joined into one molecule, made in a test tube (in vitro).

Steps

1. 1. EcoRI scans the DNA and stops at its palindrome GAATTC.
2. 2. It cuts between G and A on both strands — the staggered cut leaves AATT sticky ends.
3. 3. Foreign DNA cut by the same enzyme has matching sticky ends, so it pairs with the vector.
4. 4. DNA ligase seals the joints → recombinant DNA.

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 9.1. Report a mistake