python编程新手请教各位大侠：读取文件名为变量的一系列文件的脚本

while i < 9:
    dirs = os.listdir('sequence')
    print dirs
    for d in dirs:
        print d
        inputDNAfile = open(d,'r')
        PDBline = inputDNAfile.readline()
显示的错误信息是
['g000001.fasta', 'g000002.fasta', 'gene.fasta', 'g000003.fasta']
g000001.fasta
Traceback (most recent call last):
  File "./stepmutate.py", line 21, in <module>
    inputDNAfile = open(d,'r')      
IOError: [Errno 2] No such file or directory: 'g000001.fasta'
可是我的文件夹sequence中的确是有g000001.fasta文件的阿，所以就很迷茫阿，初次接触python语言编写脚本，望各位大侠广伸援手！