The molecule of deoxyribonucleic acid exists in the form of a double-helical structure. The DNA molecule is composed of two strands that are antiparallel in direction and are wound around one another. The backbone of the DNA is made up by the molecules of deoxyribose sugar and phosphate groups. The nitrogenous bases i.e. adenine, cytosine, guanine and thymine are attached to the sugar molecules.
The two antiparallel strands are stabilized by the formation of hydrogen bonds between the complementary bases. Adenine and thymine are held together by two hydrogen bonds whereas cytosine and guanine have three hydrogen bonds present between them. The double-helical structure of DNA was given by Watson and Crick in 1953.
Refer to Exercise 21.21. Figure E21.22 shows
The two sides of the DNA double helix are connected by pairs
The DNA molecule has the shape of a double helix (see
The compound known as nitrous acid is a reactive chemical that replaces
The technology of DNA typing had its beginnings in 1985 with the
On further analysis of the DNA described in conceptual question C21,
In what ways are the structures of an α helix in a
Take two pieces of string that are approximately 10 inches long,
Obtain two strings of different colors (e.g., black
Which of the following statements is not true? Explain why.