Pairwise Sequence Alignment (PSA) Flashcards

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1
Q

share a common evolutionary ancestry

A

Homology

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2
Q

extent to which two amino acid (or nucleotide) sequences are invariant (unchanged) = exact matching

A

Identity

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3
Q

general description of a relationship = optimal matching

A

Similarity

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4
Q

homologous sequences in different species that arose from a common ancestral gene during speciation

A

Orthologs

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5
Q

homologous sequences that arose by a mechanism such as gene duplication

A

Paralogs

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6
Q

Scoring Matrices

A

Perfect match = +1
Mismatch = 0
Gap opening = -2
Gap = -1

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7
Q

Why penalize gaps?

A

✓ maximizes the number of matches and
✓ minimizes the number of gaps

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8
Q

Protein Sequence Alignment matrices(4)

A

Identity matrix
Mutation data matrix
Physical properties matrix
Genetic code matrix

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9
Q

Protein sequence alignment matrix

o Exact matches receive one score and non-exact matches a different score (1 on the diagonal 0 everywhere else)

A

Identity matrix

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10
Q

Protein sequence alignment matrix

o a scoring matrix compiled based on observation of protein mutation rates: some mutations are observed more often than others (PAM, BLOSUM)

A

Mutation data matrix

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11
Q

Protein sequence alignment matrix

o amino acids with similar biophysical properties receive a high score.

A

Physical properties matrix

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12
Q

Protein sequence alignment matrix

o amino acids are scored based on similarities in the coding triple

A

Genetic code matrix

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13
Q

Basis of Scoring Matrices

A

Accepted Point Mutation (PAM)
Block Substitution Matrix (BLOSUM)

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14
Q

Basis of Scoring Matrices

a replacement of one amino acid in a protein by another residue that has been accepted by natural selection

A

Accepted Point Mutation (PAM)

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15
Q

Basis of Scoring Matrices

By Henikoff and Henikoff (1992, 1996)
They focused on conserved regions (blocks) of proteins that are distantly related to each other

A

Block Substitution Matrix (BLOSUM)

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16
Q

Methods of alignment

A

By Hand
Dot Plot
Rigorous Algorithm
Heuristic Methods

17
Q

Method of alignment

slide sequences on two lines of a word processor

A

By Hand

18
Q

Method of alignment

Graphical matrix

A

Dot Plot

19
Q

Method of alignment

Dynamic programming (slow, optimal)

A

Rigorous Algorithm