python检测题漏条件，请问怎么完善

图一是我对于这道题写的代码
检查时候发现我遗漏了图二题目中标黄的要求
请问如何修改这段代码才可以完善？
初学者求帮助，谢谢

img

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gene_str = input("请输入基因组字符串：")
# gene_str = "TTATGTTTTAAGGATGGGGCGTTAGTT"
end_str = ["TAG","TAA","TGA"]
exclude_str = ["ATG","TAG","TAA","TGA"]
n = len(gene_str)
res = list()
i = 0
while i < n:
    if gene_str[i:i+3] == "ATG":
        start = i+3
        while i < n:
            i += 3
            if gene_str[i:i+3] in end_str:
                res.append(gene_str[start:i])
                i += 3
                break
            if gene_str[i:i+3] in exclude_str:
                break
    else:
        i += 1
if res:
    print(*res, sep="\n")
else:
    print("No gene is found.")