Which of the following structures are external to both bacterial and archaeal cells?

A. Ribosomes
B. Pili
C. Hami
D. Peptidoglycan


Answer: B

Biology & Microbiology

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Biologists around the world spend a great deal of time studying the cytoskeleton of cells

Some of the tools they use in their research include chemicals that interfere with the structure of the cytoskeletal elements or with the activities of the motor proteins that associate with the cytoskeleton to facilitate movement. For example, a family of compounds called cytochalasins disrupts the normal assembly and disassembly of microfilaments. Another compound called colchicine binds to tubulin and prevents the assembly of microtubules. The function of dynein is prevented by a compound known as EHNA (erythro-9-[3-2- (hydroxynonyl)] adenine), and blebbistatin inhibits the activity of myosin. Use this information to answer the following questions. Based on this information, where would you predict blebbistatin to have the greatest effect? A. sperm cell motility B. leading edge formation of a migrating fibroblast C. the contraction at the trailing edge of a fibroblast D. Blebbistatin would likely have no effect on any of these examples of cell movement.

Biology & Microbiology

____________ asteroids are the most common and appear to be the source of the most common type of meteorite, the chondrites. They are more common in the inner belt and may be the source of stone meteorites

a. S-type b. M-type c. C-type

Biology & Microbiology

Atomic number is

a. number of protons b. number of electrons c. number of neutrons

Biology & Microbiology

Salmonella and Shigella, both causes of diarrhea, can be distinguished by which of the following tests?

A) lactose fermentation B) oxidase test C) motility D) urease test E) pigment production

Biology & Microbiology