Micro - Quiz 3

Bacterial cells that are variable in shape are called _________. a. pleomorphic b. vibrio c. hyphal d. coccobacilli

a. pleomorphic

In many spirochetes, multiple flagella combine to form a bundle known as a(n) _________ fibril, which winds around the cell and confers motility on the cell.

axial

Motile bacteria have been placed in an environment with a gradient of a chemical attractant. Which of the following behaviors would you predict? a. The bacteria will only exhibit runs away from the chemical. b. Bacteria will randomly switch back and forth between runs and tumbles. c. The bacteria will reduce tumbling frequency. d. The bacteria will reduce run duration in the direction of the chemical. e. The bacteria will both reduce tumbling frequency and increase run duration in the direction of the chemical.

e. The bacteria will both reduce tumbling frequency and increase run duration in the direction of the chemical.

__________ is the process through which endospores are formed within a vegetative cell.

sporulation

Order the following structures (layers) that a small molecule must pass through as it moves from outside of an encapsulated Gram-negative cell to the cytoplasm. capsule periplasm and peptidoglycan plasma membrane outer membrane

1. capsule 2. outer membrane 3. periplasm and peptidoglycan 4. plasma membrane

Many bacteria facilitate the uptake of iron by secreting low molecular weight molecules, called ___________, to form complexes with the iron that can then be readily transported into the cell.

Siderophores

The type III bacterial protein secretion machinery _________. a. is found in gram-negative bacteria b. all choices are correct c. includes structural features that may be evolutionarily related to the basal bodies of bacterial flagella d. has a needlelike structure through which proteins are secreted

b. all choices are correct

Which of the following contribute to the environmental resistance of bacterial endospores? a. low water content of endospore b. all choices are correct c. lower pH d. spore coat e. presences of calcium dipicolinate

b. all choices are correct

Which bacterial structure may survive if temperatures applied during food preservation processes are too low? a. flagella b. endospores c. plasma membrane d. ribosomes

b. endospores

Which of the following is NOT part of the process by which an endospore transforms to become a vegetative cell? a. outgrowth b. induction c. activation d. germination

b. induction

Although penicillin inhibits peptidoglycan synthesis, bacterial cells will continue to grow normally in the presence of penicillin in a(n) __________ environment. a. hypotonic b. isotonic c. nonpolar d. hypertonic

b. isotonic

Bacterial flagella are composed of three parts: the __________ body, which is embedded in the cell, the hook, and the ________, which is the longest part of the flagellum.

basal, filament

Bacterial and archaeal ribosomes are known as __________ ribosomes, based on their sedimentation coefficient. a. 30s b. 80s c. 70s d. 50s

c. 70s

Which of the following statements is false regarding the differences between bacterial and eukaryotic cytoskeletal proteins? a. The bacterial protein FtsZ is a homologue of the eukaryotic protein tubulin, and MreB and Mbl are homologues of actin. b. Proteins in the cytoplasm of bacterial cells are structurally similar to the tubulin and actin found in eukaryotic cells. c. Eukaryotic cells have cytoskeletal fibers comprised of tubulin and actin proteins, whereas bacterial cells lack cytoskeletal proteins. d. Cytoskeletal proteins in both eukaryotes and bacteria function in cell division, protein localization and determination of cell shape.

c. Eukaryotic cells have cytoskeletal fibers comprised of tubulin and actin proteins, whereas bacterial cells lack cytoskeletal proteins.

Which of the following processes can be used to bring nutrients into a cell against a concentration gradient? a. passive diffusion b. facilitated diffusion c. active transport d. active transport and facilitated diffusion

c. active transport

The lipopolysaccharide (LPS) that is found in the outer membrane of Gram-negative bacteria is also known as _________. a. murein b. teichoic acid c. endotoxin d. exotoxin

c. endotoxin

A new protein has been described that transports a growth factor across the plasma membrane. This protein is most likely a(n) _________. a. peripheral membrane protein, facing outward b. cytoplasmic protein c. integral membrane protein d. peripheral membrane protein, facing the cytoplasmic side

c. integral membrane protein

A pathogenic bacterial species has mutated and is no longer able to synthesize a capsule. Which outcome would you predict? a. The mutated bacteria will undergo osmotic lysis in hypotonic environments. b. The mutated bacteria will be more virulent. c. The mutated bacteria will be protected from plasmolysis in hypertonic environments. d. The mutated bacteria will not be able to cause disease as readily.

d. The mutated bacteria will not be able to cause disease as readily.

One type of archaeon, Haloquadratum walsbyi, is shaped like a postage stamp with dimensions of 2 µm x 3 µm x 0.25 µm. What advantage would this shape provide? a. This shape is difficult for phagocytic cells to attach to and engulf. b. This shape is more conducive to the formation of biofilm communities. c. This shape enables this bacteria to float on surfaces and obtain better light exposure. d. This shape increases the surface to volume ratio enabling more efficient nutrient uptake.

d. This shape increases the surface to volume ratio enabling more efficient nutrient uptake.

Twitching motility involves _________. a. peritrichous flagella b. monotrichous flagella c. periplasmic flagella d. type IV pilli

d. type IV pilli

Molecules or regions of molecules that readily interact with water are said to be __________, whereas molecules or regions of molecules that are insoluble in water or do not readily interact with water are said to be __________.

hydrophilic, hydrophobic

Nutrients that are used by bacteria in relatively large amounts are __________.

macronutrients

Bacteria have a region of the cytoplasm known as the __________, which is not bounded by a membrane but contains the chromosome.

nucleoid