Here are the key points about sequence and structure of proteins:
- Protein sequences can be compared to determine similarity and relate unknown sequences to known protein families/categories. Sequence databases are searched for matches.
- Sequence alignment involves sliding two sequences past each other to find the position with the most matched residues. However, it misses some alignments.
- Gaps can be introduced in alignments to account for insertions/deletions between similar sequences from different genes. This increases matching possibilities.
- Beyond simple amino acid identity comparisons, there are two types of substitutions that better reflect evolutionary changes:
1) Conservative substitutions substitute amino acids within the same chemical property groups.
2) Semi-conservative substitutions substitute amino