Review Questions Flashcards
Which of the following is most important in epithelial cell-to-cell communication?
Belt desmosomes Gap junctions Hemidesmosomes Spot desmosomes Tight junctions
Gap Junctions
These form direct cell-to-cell connections allowing communication between cells.
- Belt desmosomes (adherens junctions) provide an intercellular link between the cytoskeletons of adjacent cells.
- Hemidesmosomes anchor epithelial cells to the underlying basal lamina using integrins.
- Spot desmosomes are specialized plaques that help form strong attachments between epithelial cells.
- Tight junctions help form a tight seal laterally between epithelial cells, forming a barrier that prevents substances from passing between cells.
A gland is noted to secrete a watery, enzyme-containing substance into the GI tract, using a single straight tubule emerging from a secretory unit of cells that looks like a group of small sacs. Which of the following best describes this gland?
a Endocrine, saccular, serous b Endocrine, alveolar, mucous c Exocrine, acinar, serous d Exocrine, acinar, mucous e Exocrine, tubular, serous
Exocrine, acinar, serous
Exocrine glands excrete their product onto an epithelial surface like skin or the GI tract, whereas endocrine glands (A and B) secrete into the blood. Acinar (also known as alveolar) glands have secretory units organized as sacs, whereas tubular glands (E) are organized in small tubules. Serous glands secrete proteins, often enzymes, whereas mucous glands (B and D) secrete the slippery glycoprotein mucus.
Which of the following epithelia contains multiple layers of cells, including some columnar cells?
Pseudostratified columnar
Simple cuboidal
Simple squamous
Transitional
This is seen in the urinary tract and has multiple layers of cells resting on a columnar layer. The upper layer may appear to be cuboidal or squamous depending on whether the tissue is relaxed or stretched. Pseudostratified columnar epithelium (A) has a single layer of columnar cells but appears to have multiple layers if looking at the nuclei. Simple epithelia (B and C) have a single layer of cells.
Which of the following proteins is most directly involved in moving the ovulated egg down the fallopian tube towards the uterus?
Cadherins Connexins Dynein Integrins Mucin
Dynein
Dynein is the molecular motor for cilia, moving the microtubules and cause the cilia to move together to move the egg down the fallopian tube. Cilia are also seen in the respiratory and male reproductive tract. Connexins (B) are proteins that make up gap junctions, facilitating cell-cell communication. Cadherins (A) are contained in desmosomes, which bind cells together. Integrins (D) are seen in hemidesmosomes, which connect epithelial cells to the basement membrane. Mucin (E) is a glycoprotein that is part of mucus and secreted by some exocrine glands.
What is the purpose of fimbriae on the outer surface of bacteria?
Adhesion to surfaces Antibiotic resistance Defense against predators Ingestion of nutrients Motility
Adhesion to surfaces
Fimbriae have no known role in antibiotic resistance (B), defense against predators (C), and ingestion of nutrients (D). Flagella are more associated with bacteria motility (E).
Why do gram-positive bacteria stain violet?
a. They do not have enzymes that degrade the dye.
b. They have a thicker layer of cell membrane, which retains the dye.
c. They have thicker cell walls, which retain the dye.
d. They have two layers of cell membranes.
e. The molecular components of their cell walls bind tighter to the dye.
c. They have thicker cell walls, which retain the dye.
The Gram stain dye is not known to be degraded by any enzyme (A). Cell membrane thickness does not vary widely or readily between gram-positive and gram-negative bacteria (B). Gram-positive bacteria have one thick outer cell wall, and a layer of cell membrane underneath. Gram-negative bacteria have two layers of membrane, not gram-positive bacteria (D). Gram-positive and gram-negative bacteria have the same composition of cell wall, primarily peptidoglycan (E).
A 69-year-old man is sent to the emergency room with high fever, low blood pressure, and mental confusion. There are also large patches of bruises on his torso. He has an ongoing history of pneumonia, but these symptoms have not occurred before. A blood culture was done, and gram-negative cocci are present. Which of the following factors is the most likely cause of the patient’s symptoms?
a. Bacterial spores
b. Flagella
c. LPS
d. Mycolic acids
e. Pili
c. LPS
LPS is an endotoxin that can cause septic shock, which manifests as high fever, hypotension, easy bruising, and organ failure. Bacteria form spores in environments that are hostile to them, but bacterial spores (A) do not by themselves cause shock. Flagella (B) are involved in bacterial motility and do not cause symptoms of shock. Mycolic acids (D) are special components of the cell walls of acid-fast staining microbes, most notably Mycobacteria. Pili are features on a bacterium that enable it to adhere to surfaces, and they do not cause symptoms of shock (E).
Which of the following bacterial shape is correctly matched with its description?
a. Bacillus, rod shaped
b. Coccus, comma shaped
c. Coccus, oval
d. Spirillum, spherical
e. Vibrio, spiral
a. Bacillus, rod shaped
Cocci are spherical bacteria, so coccus, comma shaped (B) and coccus, oval (C) are incorrect. A spirillum bacterium is spiral shaped (D). An oval bacterium is termed coccobacillus, and a comma-shaped bacterium is called vibrio; vibrio, spiral (E) is therefore incorrect.
