7. Hidden Markov Models (Parte 2) (pdf, it, 413 KB, 4/28/10)
7. Hidden Markov Models (Parte 2) (pdf, it, 413 KB, 4/28/10)
7. Hidden Markov Models (Parte 2) (pdf, it, 413 KB, 4/28/10)
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Allineamento multiplo di sequenze:<br />
esempio<br />
• Si considerino CAEFDDH e CDAEFPDDH<br />
• Supponiamo che il nostro modello abbia lunghezza <strong>10</strong> e<br />
che i due cammini di v<strong>it</strong>erbi siano<br />
• M0, M1, M2, M3, M4, D5, D6, M7, M8, M9, M<strong>10</strong><br />
• M0, I1, M1, M2, M3, M4, D5, M6, M7, M8, M9, M<strong>10</strong><br />
• L’allineamento è calcolato allineando posizioni generate<br />
dallo stesso match state<br />
m 0 m 1 m 2 m 3 m 4 d 5 d 6 m 7 m 8 m 9 m 1 0<br />
C A E F D D H<br />
C D A E F P D D H<br />
m 0 m 1 i 1 m 2 m 3m 4 d 5 m 6m 7m 8m 9m 1 0<br />
0 m 1 i 1 1<br />
C – A E F – D D H<br />
C D A E F P D D H<br />
V<strong>it</strong>torio Murino Riconoscimento e Classificazione per la Bioinformatica 114<br />
114<br />
START<br />
Da V<strong>it</strong>erbi all’allineamento<br />
D D<br />
I I I<br />
A=.3<br />
G=.3<br />
C=.3<br />
T=.1<br />
A=.35<br />
G=.35<br />
T=.2<br />
C=.1<br />
Delete States<br />
If the path for a sequence S goes through one<br />
of these states, then a deletion has occurred in evolution,<br />
so we put a gap (dash) in the alignment for S<br />
Insert States<br />
If the path for a sequence S goes through one of these<br />
states, then we just put the letter from S at that pos<strong>it</strong>ion,<br />
but the other sequences in the MSA get a gap<br />
Match States<br />
If the path for a sequence S goes through one of<br />
these states, then we just put the letter from S at<br />
that pos<strong>it</strong>ion in the alignment for S.<br />
V<strong>it</strong>torio Murino Riconoscimento e Classificazione per la Bioinformatica 115<br />
115<br />
34