A) If a DNA double helix that is 100 base pairs in length has 32 adenines, how many cytosines, guanines, and thymines must it have? B) Explain what is meant by the terms conservative and Semiconservative replication A) If a DNA double helix that is 100 base pairs in length has 32 adenines, how many cytosines, guanines, and thymines must it have? B) Explain what is meant by the terms conservative and Semiconservative replication B) Explain what is meant by the terms conservative and Semiconservative replication Solution A). Genes consist of specific sequences of DNA (deoxyribonucleic acid) nucleotides otherwise called “bases,” which carry the message encoding for the synthesis of a protein. There are four such bases, namely, adenine (A), thymine (T), guanine (G), and cytosine (C), which are the building blocks of DNA’s double helical structure. Chargaff proposed that, in a double stranded DNA, the ratio of purines to pyrimidines is always 1: 1. Given that the number of adenines are 32, so, the number of thymines are also 32. The remaining 36 will be guanine and cytosine, each 18 in number. B). Gene is the physical unit of heredity that transmits information from one cell to another and thereby one generation to another. DNA (deoxyribonucleic acid) is a double helical structure; it contains the organism’s genetic information in the genes which lie along the structure of DNA. During cell division, the replication of DNA occurs, which is nothing but duplication of chromosomes. DNA replication results in the formation of two new DNA helices. The semiconservative pattern of DNA replication is demonstrated by Meselson and Stahl. In this, each strand of parent DNA act as template for the new strand, thus producing two new DNA strands. So, the newly formed DNA contains one old strand and one new strand. In conservative replication, the original strands of DNA are not forwarded to the next generation, but it act as a temple for the synthesis of new DNA. So the original double helix of DNA remains intact..

1. A) If a DNA double helix that is 100 base pairs in length has 32 adenines, how many cytosines,
guanines, and thymines must it have?
B) Explain what is meant by the terms conservative and Semiconservative replication
A) If a DNA double helix that is 100 base pairs in length has 32 adenines, how many cytosines,
guanines, and thymines must it have?
B) Explain what is meant by the terms conservative and Semiconservative replication
B) Explain what is meant by the terms conservative and Semiconservative replication
Solution
A). Genes consist of specific sequences of DNA (deoxyribonucleic acid) nucleotides otherwise
called “bases,” which carry the message encoding for the synthesis of a protein. There are four
such bases, namely, adenine (A), thymine (T), guanine (G), and cytosine (C), which are the
building blocks of DNA’s double helical structure.
Chargaff proposed that, in a double stranded DNA, the ratio of purines to pyrimidines is always
1: 1.
Given that the number of adenines are 32, so, the number of thymines are also 32. The remaining
36 will be guanine and cytosine, each 18 in number.
B).
Gene is the physical unit of heredity that transmits information from one cell to another and
thereby one generation to another. DNA (deoxyribonucleic acid) is a double helical structure; it
contains the organism’s genetic information in the genes which lie along the structure of DNA.
During cell division, the replication of DNA occurs, which is nothing but duplication of
chromosomes. DNA replication results in the formation of two new DNA helices. The
semiconservative pattern of DNA replication is demonstrated by Meselson and Stahl. In this,
each strand of parent DNA act as template for the new strand, thus producing two new DNA
strands. So, the newly formed DNA contains one old strand and one new strand.
In conservative replication, the original strands of DNA are not forwarded to the next generation,

2. but it act as a temple for the synthesis of new DNA. So the original double helix of DNA remains
intact.