public static DNA createDNAFrom35Strand(String dna) {
		if (dna == null)
			return null;
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < dna.length(); i++) {
			char n = dna.charAt(i);
			if (n == ' ')
				continue;
			if (n == 'N') {
				int nt = (int) Math.round(4 * Math.random());
				switch (nt) {
				case 0:
					n = Nucleotide.ADENINE_NAME;
					break;
				case 1:
					n = Nucleotide.GUANINE_NAME;
					break;
				case 2:
					n = Nucleotide.THYMINE_NAME;
					break;
				case 3:
					n = Nucleotide.CYTOSINE_NAME;
					break;
				default:
					n = Nucleotide.ADENINE_NAME;
					break;
				}
			}
			Nucleotide nuc = Nucleotide.getNucleotide(n);
			Nucleotide complNuc = nuc.getComplementaryNucleotide(false);
			sb.append(complNuc.toString());
		}
		return new DNA(sb.toString());
	}