创建一条有通用字母组成的模糊序列：
>>> from Bio.Seq import Seq
>>> my_seq = Seq("AGTACACTGGT")
>>> my_seq
Seq('AGTACACTGGT', Alphabet())
>>> my_seq.alphabet
Alphabet()

创建一条明确的DNA字母表对象：
>>> from Bio.Seq import Seq
>>> from Bio.Alphabet import IUPAC
>>> my_seq = Seq("AGTACACTGGT", IUPAC.unambiguous_dna)
>>> my_seq
Seq('AGTACACTGGT', IUPACUnambiguousDNA())
>>> my_seq.alphabet
IUPACUnambiguousDNA()

明确是氨基酸序列：
>>> from Bio.Seq import Seq
>>> from Bio.Alphabet import IUPAC
>>> my_prot = Seq("AGTACACTGGT", IUPAC.protein)
>>> my_prot
Seq('AGTACACTGGT', IUPACProtein())
>>> my_prot.alphabet
IUPACProtein()

可以将Seq对象处理成正常的Python字符串，比如迭代元素，取序列长度：
>>> from Bio.Seq import Seq
>>> from Bio.Alphabet import IUPAC
>>> my_seq = Seq("GATCG", IUPAC.unambiguous_dna)
>>> for index, letter in enumerate(my_seq):
... print index, letter
0 G
1 A
2 T
3 C
4 G
>>> print len(my_seq)
5

Python计数从0开始获取序列的元素：
>>> print my_seq[0] #first letter
G
>>> print my_seq[2] #third letter
T
>>> print my_seq[-1] #last letter
G

.count()像Python的字符串一样进行着非重叠的计数：
>>> from Bio.Seq import Seq
>>> "AAAA".count("AA")
2
>>> Seq("AAAA").count("AA")
2

简单计算GC含量：
>>> from Bio.Seq import Seq
>>> from Bio.Alphabet import IUPAC
>>> my_seq = Seq('GATCGATGGGCCTATATAGGATCGAAAATCGC', IUPAC.unambiguous_dna)
>>> len(my_seq)
32
>>> my_seq.count("G")
9
>>> 100 * float(my_seq.count("G") + my_seq.count("C")) / len(my_seq)
46.875

Bio.SeqUtils 模块已经 建立了GC函数：
>>> from Bio.Seq import Seq
>>> from Bio.Alphabet import IUPAC
>>> from Bio.SeqUtils import GC
>>> my_seq = Seq('GATCGATGGGCCTATATAGGATCGAAAATCGC', IUPAC.unambiguous_dna)
>>> GC(my_seq)
46.875

切取序列：
>>> from Bio.Seq import Seq
>>> from Bio.Alphabet import IUPAC
>>> my_seq = Seq("GATCGATGGGCCTATATAGGATCGAAAATCGC", IUPAC.unambiguous_dna)
>>> my_seq[4:12]
Seq('GATGGGCC', IUPACUnambiguousDNA())
序列第一个元素从0开始，第一项4序列被包含进结果，最后一项12则没有。

将序列对象转换成字符串：
尽管对 Seq 对象调用 str() 函数将以字符串的形式返回全长序列，但是当使用print打印时，Python会自动转换。
>>> str(my_seq)
'GATCGATGGGCCTATATAGGATCGAAAATCGC'
>>> print my_seq
GATCGATGGGCCTATATAGGATCGAAAATCGC

当你进行Python字符串格式化或者插入操作符（ % ）时， 可以直接把 Seq 对象和 %s 占位符一起使用：
>>> fasta_format_string = ">Name\n%s\n" % my_seq
>>> print fasta_format_string
>Name
GATCGATGGGCCTATATAGGATCGAAAATCGC

改变大小写：
>>> from Bio.Seq import Seq
>>> from Bio.Alphabet import generic_dna
>>> dna_seq = Seq("acgtACGT", generic_dna)
>>> dna_seq
Seq('acgtACGT', DNAAlphabet())
>>> dna_seq.upper()
Seq('ACGTACGT', DNAAlphabet())
>>> dna_seq.lower()
Seq('acgtacgt', DNAAlphabet())

>>> "GTAC" in dna_seq
False
>>> "GTAC" in dna_seq.upper()
True

IUPAC字母表仅仅是对于大写字母构成的序列的：
>>> from Bio.Seq import Seq
>>> from Bio.Alphabet import IUPAC
>>> dna_seq = Seq("ACGT", IUPAC.unambiguous_dna)
>>> dna_seq
Seq('ACGT', IUPACUnambiguousDNA())
>>> dna_seq.lower()
Seq('acgt', DNAAlphabet())