基因序列比较

人类基因由4种核苷酸，分别用字母ACTG表示。要求编写一个程序，按以下规划比较两个基因序列并确定它们的相似程度。即两

给出两个基因序列AGTGATG和GTTAG，它们有多相似呢？测量两个基因的相似度一种方法称为对齐。使用对齐方法可以在基因的适当位置加入空格，让两个基因的长度相等，然后根据基因的分值矩阵计算分数。

　　A　　C　　G　　T　　-

A　　5　　-1　　-2　　-1　　-3

C　　-1　　5　　-3　　-2　　-4

G　　-2　　-3　　5　　-2　　-2

T　　-1　　-2　　-2　　5　　-1

-　　-3　　-4　　-2　　-1　　*



比较AGTGATG与GTTAG

第一种对齐方案为：

首先可以给AGTATG插入一个空格得：AGTAT-G

GTTAG插入3个空格即得：-GT--TAG

上面的匹配分值为:-3+5+5+(-2)+(-3)+5+(-3)+5=9.

第二种对齐方案为：

AGTGATG

-GTTA-G

得到的分值为：(-3)+5+5+(-2)+5+(-1)+5=14.

当然还有其它对齐方式，但以上对齐方式是最优的，所以两个基因的相似度就为14。-Comparison of sequences from the human gene of the four nucleotides, respectively, by the letters ACTG. Requested to prepare a program to compare two gene sequences according to the following plan and determine their degree of similarity. Given that two and two gene sequences AGTGATG GTTAG, how they are similar to it? A method of measuring the similarity of two genes called alignment. Alignment method using a space can be added in place of the gene, so that equal lengths of the two genes, and calculating scores according to scoring matrix gene. ACGT- A 5-1-2-1-3 C-1 5-3-2-4 G-2-3 5-2-2 T-1-2-2 5-1- 3-4-2- 1* Compare AGTGATG GTTAG first aligned with the program as follows: First give AGTATG insert a space too: AGTAT-G GTTAG that was inserted into three spaces:-GT- TAG at the match score is:-3+5+5+ (-2 .)+ (-3)+5+ (-3)+5 = 9 second-aligned solutions for: AGTGATG-GTTA-G to get the score of: (-3)+5+5+ (-2)+5+ (-1)+5 = 14 Of course there are other alignment, but the above is the optimal ali