Question 1

Rough endoplasmic reticulum (RER)in the cell cytoplasm is intensely stained by hematoxylin because hematoxylin:&#10;A) Attaches to lipids in RER membranes&#10;B) Binds readily to RNA&#10;C) Catalyzes the precipitation of ribosomes into a dense,readily stained matrix&#10;D) Is an acid dye and binds to acidophilic ribosomal proteins&#10;E) Reacts with carbohydrate molecules of integral membrane proteins

Accepted Answer

Hematoxylin is a basic dye that binds readily to acidic structures such as RNA. The rough endoplasmic reticulum is studded with ribosomes, which are composed of RNA and protein, and thus intensely stained by hematoxylin.

Question 2

Numerous mitochondria possessing unusual tubular cristae are a distinguishing anatomic feature of:&#10;A) Exocrine pancreatic acinar cells&#10;B) Nerve cells of the cerebral cortex&#10;C) Pancreatic islet cells&#10;D) Skeletal muscle cells&#10;E) Steroid-secreting cells in the adrenal cortex

Accepted Answer

Steroid-secreting cells in the adrenal cortex are characterized by numerous mitochondria with unusual tubular cristae, which are involved in the synthesis of steroid hormones.

Question 3

Tay-Sachs disease results from abnormalities in:&#10;A) Keratin&#10;B) Lysosomes&#10;C) Microtubules&#10;D) Mitochondria&#10;E) Rough endoplasmic reticulum

Accepted Answer

Tay-Sachs disease is a genetic lysosomal storage disorder caused by the deficiency of the enzyme hexosaminidase A, leading to the accumulation of ganglioside GM2 in the lysosomes of neurons. This accumulation ultimately results in progressive neurodegeneration.

Question 4

Staining a specimen using immunocytochemical methods detects the presence of:&#10;A) Lipids with multiple double bonds between carbon atoms&#10;B) Organelles with an above average optical density&#10;C) Specific types of carbohydrates&#10;D) Specific proteins&#10;E) Specific sequences of RNA

Accepted Answer

Immunocytochemical methods involve using antibodies that bind to specific proteins, allowing their presence to be detected and visualized. Therefore, staining a specimen using immunocytochemical methods detects the presence of specific proteins.

Question 5

Lipofuscin is a brownish pigment that may accumulate in:&#10;A) Lipid droplets&#10;B) Lysosomes&#10;C) Mitochondria&#10;D) Smooth endoplasmic reticulum&#10;E) The cell nucleus

Accepted Answer

Lipofuscin is a residual substance composed of lipids and proteins that accumulates in lysosomes as a result of cellular aging or stress.

Question 6

A function of the Golgi complex includes:&#10;A) Degradation of abnormal proteins&#10;B) Destruction of hydrogen peroxide&#10;C) Glycosylation of proteins&#10;D) Storage of calcium&#10;E) Translation of messenger RNA

Accepted Answer

The Golgi complex is responsible for modifying and sorting proteins, including adding carbohydrates (glycosylation) to them. It is not involved in the degradation of abnormal proteins, destruction of hydrogen peroxide, storage of calcium, or translation of messenger RNA.

Question 7

Claudin is a protein that is functionally important in:&#10;A) Gap junctions&#10;B) Hemidesmosomes&#10;C) Intermediate junctions&#10;D) Synapses&#10;E) Tight junctions

Accepted Answer

Claudin is a protein that is functionally important in tight junctions, which are structures that seal the intercellular space between epithelial cells, preventing the diffusion of molecules between cells.

Question 8

Desmin is an intermediate filament protein that is specifically localized in:&#10;A) Astrocytes&#10;B) Cardiac muscle&#10;C) Lymphocytes&#10;D) Macrophages&#10;E) Simple cuboidal epithelial cells

Accepted Answer

Desmin is specifically localized in cardiac muscle cells, where it provides structural support and helps to maintain the alignment of contractile elements. It is also expressed in smooth and some skeletal muscle cells. Astrocytes do express intermediate filament proteins, but they are not typically desmin. Lymphocytes, macrophages, and simple cuboidal epithelial cells do not typically express desmin.

Deck 1: The Cell