Chapter 12, Problem 5A

Summary Introduction

Introduction:

Many scientists performed different experiments to know that which macromolecule is the source of genetic information in any cell. Work of Fredrick Griffith, Avery, Hershey, and Chase helped in the discovery of DNA as genetic material. Griffith studied two strains of Streptococcus pneumonia. One strain is sugar-coated named Smooth (S) strain which causes pneumonia another strain is non-coated and does not cause pneumonia, known as called Rough(R) strain.

Answer to Problem 5A

Correct answer:

The correct answer is option (C) Bacteria exposed to DNA can incorporate the DNA and change phenotype.

Explanation of Solution

Explanation/justification for the correct answer:

Griffith’s transformation experiment demonstrated the change of rough strain bacteria into smooth strain bacteria. The disease-causing factor was passed from the killed S bacteria to live R bacteria.

Explanation for incorrect answer:

Option (A) DNA is the genetic material in the Virus: Hershey and Chase radioactive labeling experiment demonstrated that DNA is the genetic material in the Virus.

Option (B) The structure of DNA is a double helix: Watson and Crick, with the help of Wilkin’s and Franklin’s X-ray diffraction data, proposed the DNA double helix structure.

Option (D) The amount of thymine equals the amount of adenine in DNA:Erwin Chargaff analyzed the amount of nitrogen base in DNA. Chargaff’s rule: C=G, T-A.