I would like to ask you about the Python sequence list element modification.

We're working on a simple code that represents the DNA sequence in Python.

Code that stores the base sequence in the list when it is entered, transforms the list element according to the rule with a for statement and an if statement, and outputs the changed list. (Rule: A --> T, T --> A)

But if I did it like I planned it, the for statement was executed, and I changed only a[0] and I didn't touch a[1] and a[2].

So even if I input ATA, the if statement is applied only to a[0] and ['T', 'T', 'A'] is printed out like this. (If it is printed correctly according to the rule, it should be printed as ['T', 'A', 'T']) How do you apply the if statement to a[1], a[2] and output it correctly according to the rule?

DNA_list = list (map(str, input("Enter 3 base sequence").split())) 
a = DNA_list

for i in a:
  if (i == "A") :
    a[a.index("A")] = "T"

  elif (i == "T") :
    a[a.index("T")] = "A" 

  else :
    a = "You entered the wrong sequence"

print(a)