CELL STRUCTURE AND FUNCTION

The cell is the smallest entity that still retains the characteristics of life. All cells have three basic parts:

1. A plasma membrane which separates each cell from the environment. It permits the flow of molecules across the membrane, and contains receptors that can affect the cell's activities.
2. A DNA-containing region which occupies a portion of the interior.
3. The cytoplasm which contains membrane-bound compartments or organelles (except in bacteria), particles, and filaments. These are bathed in a semifluid substance.

Organelles form compartmentalized portions of the cytoplasm. All eukaryotic cells contain organelles. The nucleus, endoplasmic reticulum, Golgi bodies, vesicles, and mitochondria are all organelles bounded by membranes.

Organelles separate reactions with respect to time (allowing proper sequencing) and space (allowing incompatible reactions to occur in close proximity).

REVIEW: Organelles _____ .
a. are membrane-bound compartments
b. are typical of eukaryotic cells, not prokaryotic cells
c. separate chemical reactions in time and space
d. all of the above are features of the organelles
Answer d