Biology Chapter 1 Quiz

Study Notes

This lecture introduces medical and oral biology.
The outline topics include: what oral biology is, medical biology, the cell, the cell theory, an overview of the cell, and types of cells.

Oral biology is a branch of dentistry.
It studies embryology (prenatal and postnatal growth), oral physiology, gross anatomy, histology, and development.
Key focus is on dental hard and soft tissues (enamel, dentin, pulp, and periodontium) and extraoral structures like salivary glands and TMJ.

Cells are the basic units of life.
Organisms are composed of cells.
Unicellular organisms consist of a single cell and perform all life functions independently.
Multicellular organisms are composed of many cells.
Cells are the fundamental structural and functional units of all living organisms.

1838: Matthias Schleiden (botanist) observed plants are made of cells.
1839: Theodore Schwann (zoologist) observed similar cell structures in animals.
Together they proposed a cell theory, but it did not yet explain how new cells form.
1855: Rudolf Virchow corrected the theory stating all cells arise from pre-existing cells (omni cellula e cellula).
Modern cell theory: All living organisms are composed of cells and cell products; all cells come from pre-existing cells.

Cells vary greatly in size, shape, and activity.
Mycoplasmas are the smallest cells (0.3 µm) while some cells are large (ostrich egg).
Human red blood cells are roundish, other cells are polygonal, columnar, cuboid, thread-like, or irregular.
The cell shape often reflects the function it performs.
Cells have an outer membrane that delimits the cell.
Inside the membrane is cytoplasm, a semi-fluid matrix of cellular activities.

Prokaryotic Cells: bacteria, blue-green algae, mycoplasma, PPLO.
- Generally smaller than eukaryotic cells.
- Reproduce rapidly
- They have a simple structure with no membrane-bound organelles.
- Four basic shapes: bacillus (rod-like), coccus (spherical), vibrio (comma-shaped), and spirillum (spiral).
Eukaryotic Cells: protists, plants, animals, fungi.
- Larger and more complex than prokaryotic cells.
- Compartmentalized cytoplasm with membrane-bound organelles.
- Cells organized nucleus with genetic material organized in chromosomes.
- Unique characteristics like cell walls, plastids and/or a large central vacuole (plant cells)
- Animal cells have centrioles that are absent in most plant cells.
Organelles in eukaryotic cells: endoplasmic reticulum, Golgi complex, lysosomes, mitochondria, microbodies, ribosomes, vacuoles.
Ribosomes are found in all cells, prokaryotic and eukaryotic.
- Found in the cytoplasm, but also within chloroplasts, mitochondria, and on rough ER.