Autotrophic organisms such as plants, algae, blue green alga, and chemosynthetic bacteria are rarely mentioned in pathology because they do not cause disease in other types of living things. What is it about the metabolic machinery of autotrophs that makes them unlikely to cause disease in people?

How does the structure of a plasmodesma differ from that of a gap junction?

The genus Ferroplasma consists of a few species of acid-loving archaea. One species, F. acidarmanus, was discovered to be the main component of slime streamers (a type of biofilm) deep inside an abandoned California copper mine (Figure 4.11A). F. acidarmanus cells use an ancient energy-harvesting pathway that combines oxygen with ironsulfur compounds in minerals such as pyrite. This reaction dissolves the minerals, so groundwater that seeps into the mine ends up with extremely high concentrations of metal ions such as copper, zinc, cadmium, and arsenic. The reaction also produces sulfuric acid, which lowers the pH of the water around the cells to zero. Despite living in an environment with a composition similar to hot battery acid, F. acidarmanus cells maintain their internal pH at a cozy 5.0. Thus, researchers investigating Ferroplasma metabolic enzymes were surprised to discover that most of the cells enzymes function best at very low pH (Figure 4.11B). A. Deep inside one of the most toxic sites in the United States: Iron Mountain Mine, in California. The water in this stream, which is about 1 meter (3 feet) wide in this photo, is hot (around 40C, or 104F), heavily laden with arsenic and other toxic metals, and has a pH of zero. Slime streamers growing in it are a biofilm dominated by a species of archaea, Ferroplasma acidarmanus. B. pH profiles of four enzymes isolated from F. acidarmus. Researchers had expected these enzymes to function best at the cells cytoplasmic pH (5.0). What does the dashed line signify?

Which of these statements is true? An antibiotic is any substance produced by a organism that is antagonistic to the growth of prokaryotes An antibiotic is any substance produced by a prokaryote that is antagonistic to the growth of other viruses An antibiotic is any substance produced by a prokaryote that is antagonistic to the growth of eukaryotic cells An antibiotic is any substance produced by a prokaryote that prevents growth of the same prokaryote.

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. What measures have been taken to stop BSE?

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.

Prokaryotes that obtain their energy from chemical compounds are called _____. a. photorophs b. auxotrophs c. chemorophs d. lithotrophs

Your friend believes that prokaryotes are always detrimental and pathogenic. How would you explain to them that they are wrong?

Describe nitrogen fixation and why it is important to agriculture.

Chemiosmosis involves. the movement of electrons across the cell membrane the movement of hydrogen atoms across a mitochondrial membrane the movement of hydrogen ions across a mitochondrial membrane the movement of glucose through the cell membrane