SCIENTIFIC SKILLS EXERCISE Working with Data in a Table Give

SCIENTIFIC SKILLS EXERCISE Working with Data in a Table Given the Percentage composition of One Nucleotide in a Genome, can we Predict the Percentages of the other Three Nucleotides? Even before the structure of DNA was elucidated, Erwin Chargaff and his coworkers noticed a pattern in the base composition of nucleotides from different organisms: The percentage of adenine bases, and the percent- age of cytosine (C) bases roughly equaled that of guanine (G) bases. Further, the percentage of each pair or C/G) varied from species to species. We now know that the 1:1 AVT and C/G ratios are due to in complementary base pairing between A and T and between c and G DNA double helix, and interspecies differences are due to the unique sequences of bases along a DNA strand. In this exercise, you will apply Chargaff\'s rules to predict the composition of bases in a genome. How the Experiments were Done In Chargaff\'s experiments, DNA was extracted from the given organism, hydrolyzed to break apart the provided approximate values for each type of nucleotide. Today, whole- genome sequencing allows base composition analysis to be done more precisely directly from the sequence data.) Data from the Experiments Tables are useful for organizing sets of data representing a common set of values (here, percentages of A, G C, and for a number of different samples (in this case, from different species). You can apply the patterns that you see in the known data to predict unknown values. In the table at the upper right, complete base distribution data are given for sea urchin DNA and salmon DNA; you will use Chargaff\'s rules to fill in the rest of the table with predicted values.

Solution

1.Given-

In sea urchin-

A= 32.8%; T= 32.1%

G=17.7%; C= 17.3%

In salmon-

A= 29.7%; T= 29.1%

G=20.8%; C=20.4%

Based on the given data, the % of Adenine is approximately equal to the % of Thymine and the % of Guanine is approximately equal to the % of Cytosine in sea urchin as well as in salmon. Hence, both follow chargaff\'s rule.