1. Yes, histology is the study of cells, tissues, and organs.
2. Yes, the most commonly examined specimens for histological studies with the light
microscope are thin sections of tissues that are stained to enhance their features.
3. The first step in the preparation of a tissue sample is fixation. Its function is to preserve the
tissue structure and prevent decay.
4. The second step in the preparation of a tissue sample is dehydration, which involves
removing water from the tissue using a series of alcohol solutions.
5. The third step in the preparation of a tissue sample is clearing, which involves using a solvent
to make the tissue more transparent before embedding it in a solid medium.
6. Eosin is an acidic dye (pink) and carries a net negative charge. It reacts with positively
charged cationic groups in cells and tissues, particularly amino groups of proteins (eosinophilic
structures).
7. Hematoxylin acts as a basic dye (blue) and carries a net positive charge. It reacts with
negatively charged ionized phosphate groups in nucleic acids (basophilic structures).
8. The periodic acid–Schiff (PAS) reaction stains glycogen and carbohydrate-rich molecules a
distinctive magenta color. It is used to demonstrate glycogen in cells, mucins in cells and
tissues, the basement membrane, and reticular fibers in connective tissue.
9. The resolving power of a bright-field microscope is about 0.2 micrometers (200 nanometers).
10. Transmission electron microscopes (TEMs) use the interaction of a beam of electrons with a
specimen to produce an image. The theoretical resolving power of a TEM is about 0.1
nanometers (angstroms).
11. Scanning electron microscopes (SEMs) have a resolving power of about 3-10 nanometers.
They use electrons emitted or forced out of the specimen surface that are collected by detectors
and reprocessed to form an image of a sample's surface.
12. Atomic force microscopes (AFMs) have a resolving power of about 1 nanometer. They are
scanning microscopes that utilize an ultra-sharp, pointed probe (cantilever) dragged across the
surface of a specimen. Up and down movements of the cantilever are recorded and transformed
into a graphic image.
13. Cells are the basic structural and functional units of living organisms.
14. Cells have two major compartments: the cytoplasm (contains organelles and inclusions
surrounded by cytoplasmic matrix) and the nucleus (contains the genome).
15. Organelles are specialized structures within cells that perform specific functions.
16. Organelles are classified into membrane-bound and non-membrane-bound organelles.
17. The plasma membrane is a selectively permeable lipid bilayer that surrounds the cell,
separating it from its external environment.
18. The plasma membrane has an amphipathic character, meaning it has both hydrophobic
(water-repelling) and hydrophilic (water-attracting) regions.
19. Proteins that have important functions in cell metabolism, regulation, and integration are
called integral membrane proteins.
20. The six types of integral membrane proteins are channel proteins, carrier proteins, cell
adhesion molecules, receptor proteins, enzymatic proteins, and anchor proteins.
