# How many times will EcoR1 cut a random 10kb DNA fragment? How does this change for linear or circular DNA?

##### 1 Answer

May 31, 2015

Here's my initial answer. Requires refining from someone who understands probability better.

Each base can be ATCG. (4 possibilities)

EcoR1 recognizes a 6bp sequence, which is one out of 4^6 possibilities.

So for a 10kb linear fragment, there are (10k-5) such possibilities.

So number of cuts is 9995/(4^6)?

Or is there a better way to answer this?