Amino Acid Identity Table 8 Family How have amino acid sequences of human globin
ID: 267636 • Letter: A
Question
Amino Acid Identity Table 8 Family How have amino acid sequences of human globin genes diverged during their evolution? To build a model of the evolutionary history of the globin geres, researchers compared the amino acid sequences of the polypeptides they encode. In this exercise, you wil analyze comparisons of the amino acid sequences of globin polypeptides to see how scientists shed light on their evolutionary relationships. a Family ENER qarma G) Scientists obtained the DNA sequences for each of the eight globin genes and translated them into amino acid sequences. They then used a computer program to align the sequences and calculate a percent identity value for each pair. The percent identity reflects the number of positions with identical amino acids relative to the total number of amino acids in a globin polypeptide. E 42 42 41 The following table shows an example af a pairwise alignment that of the as glabin (alpha-1 globin) and globin (zeta globin) amino acid sequences using the standard single letter symbols for amino acids. To the left af each line of amino acid sequence is the number of the first amino acid in that ina. (a) (bela) (della) (epsion) gam A) 81 45 44 39 42 61 45 44 39 42 38 40 41 41 ----- 837673 --- 73 71 & Globin Alignment of Globin Amino Acid Sequences OLL MSE SE NE ON MAC ORA E GAME B E 31 ERMF L S FPT TKTY FPH FDL SH - GS AQVKGH ERL FLSH POTKT YF P H FDL - HP GSAQLRA OL 61 GKKVADA L TNAVAH V DDMPNAL SALSD LHA C 81 GSK V VAA VGDAVKSIDDIGGAL SKL SELHA | 01 HKL RVDP VNF KILLS HCLL VTLA AHL PAEFT ( 91 YILRVDPVN FKL LSH CLLVTLA A RFPAD FT COL 121 PA V HASLDKFLASV S T VLT SKYR S 121 AE AHAA WDK FLSV vs S VLI E The percent identity value for the ar- and C-globin amino acid sequences was calculated by counting the number of matching amino acids (87), dividing by the total number of amino acid positions (143) and then multiplying by 100. This resulted in a 61% identity value for the art pair. Further Reading R. C. Hardison, Globin genes on the move, Joumal of Biology 7:35.1–35.5 (2008). doi:10.1186/b10192Explanation / Answer
Q.Part A what is the percent identity between the ? and ? globin sequences?
Ans: 76%
This can be estimated from table If we see value of ? row to ? column, the intersection value is 76.
Q.What percent identity is implied by the dashes?
Ans: 100% identity
The cell compares the amino acid sequence with the same protein. In this table row and columns are compared for analysis. Hence it is not required to compare similarity of sequence with identical exact protein. For instance the protein is identical there is 100% identity.
Q.Notice that the cells in the lower left half of the table are blank. Why?
Ans: Yes we can observe that the cells in the lower left half of the table are blank because these cells represent duplicates of the comparisons in the upper right half of the table.
It will result in only duplication of data so the cells are kept blank.
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