Question

3. When the base composition of double-stranded DNA from Micrococcus luteus was determined, 37.5% of the bases were found to be cytosine. What is the percentage of adenine in the DNA of this organism? _____ % adenine

4. A region along a DNA strand that is transcribed contains no A. What base will be missing in the corresponding region of the mRNA? _____________

Answer 1

Answer=

3. When the base composition of double-stranded DNA from Micrococcus luteus was determined,

37.5% of the bases were found to be cytosine.

C=37.5%

according to chargaffs law DNA from any organism should have 1:1 ratio of pyrimidine & purine.

Guanine should be equal to Cytosine & Adenine should be equal to Thymine.

Guanine = 37.5%

Total bases present in DNA are

Adenine + Cytosine + Guanine + Thymine = 100%

But A=T

A +A +37.5 +37.5 =100

2Adenine = 100- 75

2Adenine = 25

Adenine =25/2 = 12.5 %

should contain 12.5 % of Adenine.

4. A region along a DNA strand that is transcribed contains no A. What base will be missing in the corresponding region of the mRNA? _____________

answer= Uracil

because Adenine in DNA is transcribed into Uracil in case of RNA

adenine pairs with Uracil in RNA.

if Adenine is absent in DNA ,Uracil is missing from RNA.