11.E: Biochemistry of the Genome (Exercises)

11.1: Using Microbiology to Discover the Secrets of Life

DNA was discovered and characterized long before its role in heredity was understood. Microbiologists played significant roles in demonstrating that DNA is the hereditary information found within cells. In the 1850s and 1860s, Gregor Mendel experimented with true-breeding garden peas to demonstrate the heritability of specific observable traits. In 1869, Friedrich Miescher isolated and purified a compound rich in phosphorus from the nuclei of white blood cells; he named the compound nuclein.

Multiple Choice

Frederick Griffith infected mice with a combination of dead R and live S bacterial strains. What was the outcome, and why did it occur?

1. The mice will live. Transformation was not required.
2. The mice will die. Transformation of genetic material from R to S was required.
3. The mice will live. Transformation of genetic material from S to R was required.
4. The mice will die. Transformation was not required.

Answer

D

Why was the alga Acetabularia a good model organism for Joachim Hämmerling to use to identify the location of genetic material?

1. It lacks a nuclear membrane.
2. It self-fertilizes.
3. It is a large, asymmetrical, single cell easy to see with the naked eye.
4. It makes a protein capsid.

Answer

C

Which of the following best describes the results from Hershey and Chase’s experiment using bacterial viruses with ³⁵S-labeled proteins or ³²P-labeled DNA that are consistent with protein being the molecule responsible for hereditary?

1. After infection with the ³⁵S-labeled viruses and centrifugation, only the pellet would be radioactive.
2. After infection with the ³⁵S-labeled viruses and centrifugation, both the pellet and the supernatant would be radioactive.
3. After infection with the ³²P-labeled viruses and centrifugation, only the pellet would be radioactive.
4. After infection with the ³²P-labeled viruses and centrifugation, both the pellet and the supernatant would be radioactive.

Answer

A

Which method did Morgan and colleagues use to show that hereditary information was carried on chromosomes?

1. statistical predictions of the outcomes of crosses using true-breeding parents
2. correlations between microscopic observations of chromosomal movement and the characteristics of offspring
3. transformation of nonpathogenic bacteria to pathogenic bacteria
4. mutations resulting in distinct defects in metabolic enzymatic pathways

Answer

B

According to Beadle and Tatum’s “one gene–one enzyme” hypothesis, which of the following enzymes will eliminate the transformation of hereditary material from pathogenic bacteria to nonpathogenic bacteria?

1. carbohydrate-degrading enzymes
2. proteinases
3. ribonucleases
4. deoxyribonucleases

Answer

D

Fill in the Blank

The element ____________ is unique to nucleic acids compared with other macromolecules.

Answer

phosphorus

In the late 1800s and early 1900s, the macromolecule thought to be responsible for heredity was ______________.

Answer

protein

Short Answer

Why do bacteria and viruses make good model systems for various genetic studies?

Why was nucleic acid disregarded for so long as the molecule responsible for the transmission of hereditary information?

Bacteriophages inject their genetic material into host cells, whereas animal viruses enter host cells completely. Why was it important to use a bacteriophage in the Hershey–Chase experiment rather than an animal virus?

Critical Thinking

In the figure shown, if the nuclei were contained within the stalks of Acetabularia, what types of caps would you expect from the pictured grafts?

Why are Hershey and Chase credited with identifying DNA as the carrier of heredity even though DNA had been discovered many years before?