dna_analyze.py

def is_valid_dna(seq):
    valid = set("ATCG")
    return all(base in valid for base in seq)

def gc_content(seq):
    gc = seq.count("G") + seq.count("C")
    return round((gc / len(seq)) * 100, 2)

def nucleotide_count(seq):
    return {
        "A": seq.count("A"),
        "T": seq.count("T"),
        "G": seq.count("G"),
        "C": seq.count("C"),
    }

def dna_to_rna(seq):
    return seq.replace("T", "U")

def reverse_complement(seq):
    complement = {"A":"T", "T":"A", "G":"C", "C":"G"}
    return "".join(complement[base] for base in seq[::-1])


dna = input("Enter DNA sequence (A,T,G,C only): ").upper()

if not is_valid_dna(dna):
    print("❌ Invalid DNA sequence!")
else:
    print("\n✅ DNA Sequence is valid!\n")
    print("📌 Length:", len(dna))
    print("📌 GC Content:", gc_content(dna), "%")
    print("📌 Nucleotide Count:", nucleotide_count(dna))
    print("📌 RNA Sequence:", dna_to_rna(dna))
    print("📌 Reverse Complement:", reverse_complement(dna))