Question

"Now that you have come up with an equation that describes the relationship between amounts of different nucleotide bases in DNA, can you use it to predict the amounts of all four nucleotide bases when you only know the amount of one type of base? Approximately 21% of the human genome is comprised of nucleotides containing C. Given this information, calculate the percentage of the human genome that is comprised of nucleotides containing G, T, and A."

Answer 1

C- 21%

G- 21%

A - 29%

T - 29%

Step-by-step explanation:

Four nucleotides make up the DNA molecule, and the sum of all four nuceleotides must equal 100% i.e.

A + G + C + T = 100%

If A -T and G - C pairs in the DNA, it means they each nucleotide must contain same proportion as its complementary pair. Therefore, if C is 21%, G is Al 21%.

Hence, 21 + 21 = 42%

We are left with the proportion of the other two nucleotides (A and T). We find it by saying 100 - 42 = 58%

Hence, if A and T must contain equal proportion, each will contain 58/2 = 29%.

The proportions of the four nuceleotides are 21, 21, 29 and 29 % for C, G, A and T respectively.

Answer 2

G - 21%

T - 29%

A - 29%

Step-by-step explanation:

Nucleotide bases in DNA are complementary. Adenosine (A) binds to Thymine (T) while Cytosine (C) binds to Guanine (G). Hence the composition of A in DNA is the same as that of T; and that of C is the same as that of G.

From the information given, C is 21%

Therefore G is also 21% of the genome as C is bound to G, the therefore are the same proportion.

C and G make up 42% of the genome (that 21% + 21%).

The remaining 58% (100%-42%) is made up of A + T

Similarly the proportion of A is equal to that of T,

Hence A is 29% (half of 58%) and T is 29%.