Chapter 10, Problem 4RQ

There have been recurring cases of mad-cow disease in the United Kingdom since the mid-1990s. Mad-cow disease is caused by a prion, an infectious particle that consists only of protein. In 1986, the media began reporting that cows all over England were dying from a mysterious disease. Initially, there was little interest in determining whether humans could be affected. For 10 years, the British government maintained that this unusual disease could not be transmitted to humans. However, in March 1996, the government did an about-face and announced that bovine spongiform encephalopathy (BSE), commonly known as mad-cow disease, can be transmitted to humans, where it is known as variant Creutzfeldt-Jakob disease (vCJD). As in cows, this disease eats away at the nervous system, destroying the brain and essentially turning it into a spongelike structure filled with holes. Victims experience dementia; confusion; loss of speech, sight, and hearing; convulsions; coma; and finally death. Prion diseases are always fatal, and there is no treatment. Precautionary measures taken in Britain to prevent this disease in humans may have begun too late. Many of the victims contracted it over a decade earlier, when the BSE epidemic began, and the incubation period is long (vCJD has an incubation period of 10 to 40 years). A recent study concluded that 1 in 2,000 people in Great Britain carry the abnormally folded protein that causes vCJD. In spite of these numbers, the death rate from vCJD remains low. It is not clear whether this means that the incubation period for the disease is much longer than previously thought, or whether they may never develop the disease. If you were traveling in Europe, would you eat beef? Give sound reasons why or why not.

Describe how seroconversion works in HIV disease.

If you suspected that heterozygous carriers of a particular disease gene had a selective advantage in resisting a type of infection, how would you go about testing that hypothesis?

What is the difference between an allergy and an autoimmune response?

In _______, viral DNA becomes integrated into a bacterial chromosome and is passed to descendant cells. a. binary fission c. the lysogenic pathway b. the lytic pathway d. conjugation

Figure 17.6 Influenza virus is packaged in a viral envelope, which fuses with the plasma membrane. This way, the virus can exit the host cell without killing it. What advantage does the virus gain by keeping the host cell alive?

Many individuals with metabolic diseases are normal at birth but show symptoms shortly thereafter. Why?

Arrange the following list into the correct sequence for viral reproduction: 1. penetration 2. assembly 3. replication 4. attachment 5. release (a) 1, 2, 3, 4, 5 (b) 5, 2, 3, 4, 1 (c) 4, 1, 3, 2, 5 (d) 4, 1, 2, 3, 5 (e) 3, 1, 2, 4, 5

Jane Doe is infected with HIV. One of her medications is acyclovir, which is a/an ____________________ drug used to treat viral infections or to provide temporary immunity.