diff --git a/Code/Replication.py b/Code/Replication.py
new file mode 100644
index 0000000..93ac561
--- /dev/null
+++ b/Code/Replication.py
@@ -0,0 +1,6 @@
+def PatternCount(Text, Pattern):
+    count = 0
+    for i in range(len(Text)-len(Pattern)+1):
+        if Text[i:i+len(Pattern)] == Pattern:
+            count = count+1
+    return count
diff --git a/Notebook.org b/Notebook.org
index 1d86d97..5e37ce7 100644
--- a/Notebook.org
+++ b/Notebook.org
@@ -9,3 +9,16 @@
      Locating an ori is key for gene therapy (e.g. viral vectors), to introduce a theraupetic gene.
      
 **** Exercise: computational approach to find ori in bacteria
+     
+     We'll look for the *DnaA box* sequence, using a sliding window, in that case our code would be the following:
+     
+    #+begin_src python
+      count = 0
+      
for i in range(len(Text)-len(Pattern)+1):
+        if Text[i:i+len(Pattern)] == Pattern:
+          count = count+1 
+      print(Pattern + ": " + count)
+    #+end_src 
+
+*** Vocabulary
+      - k-mer: subsquences of length /k/ in a biological sequence