Learn to Program: The Fundamentals // Assignment 2

Preface

Required Preparation

This handout assumes that you have watched all the week 4 videos and also done the week 4 exercise. If you read this handout before you've done all of that, please come back and re-read it after you've passed the week 4 exercise.

A2 Problem Domain: Deoxyribonucleic Acid (DNA)

DNA is the double-stranded molecule that encodes genetic information for living organisms. DNA is made up of four kinds of nucleotides, which are molecules that bond together to form DNA sequences.

The four nucleotides are adenine (A), guanine (G), cytosine (C), and thymine (T). Each strand of DNA is a sequence of nucleotides, for example AGCTAC. In a program, we will use a string representation of this, "AGCTAC".

DNA has 2 strands in a double helix. The nucleotides in one strand are bonded to the nucleotides in the other strand. A and T can be bonded together, and thus complement each other; similarly, C and G are complements of each other.

You can see a picture of this on the Wikipedia page for DNA. The two strands in DNA are complementary because each nucleotide in one strand is bonded with its complement in the other strand. Thus, given the DNA sequence ACGTACG, its complementary strand is TGCATGC.

Terminology in this handout

A DNA sequence is a sequence of nucleotides, such as TCATGT.

I solved all the required functions for this assignment.