BIOL 102 NOTES – CHAPTER 3 PART A
STRUCTURE & FUNCTION OF CELL
Cell Doctrine:
•All living things are composed of cells
•A single cell is the smallest unit that exhibits all of the characteristics of life
•All cells come only from preexisting cells
Two Basic Cell Types Classified by Internal Organization
Prokaryotic
Cells:
•Plasma membrane
•No nucleus
•Cytoplasm: fluid within membrane
•No true organelles
Eukaryotic
Cells:
•Plasma membrane
•Nucleus: information center
•Cytoplasm: fluid within membrane
•Organelles: structures with specialized functions
•All human cells are eukaryotic
Cell Structure Reflects Cell Function
•Though eukaryotic cells are remarkably similar, there are structural differences
oExamples:
▪Muscle cells – contain numerous organelles providing energy needed for
muscle contraction
▪Nerve cells – long and thin to carry impulses over distance
•Small size is efficient
Everything we know about cells comes from and microscopy biochemistry.
Cells Remain Small to Stay Efficient
•Small cells have a high surface to volume ratio
•High surface to volume ratio promotes efficiency in
oAcquisition of nutrients
