Lesson 3 Definitions Flashcards
Prokaryote
no nucleus, much smaller, capsule or “exoskeleton”
Eukaryote
has nucleus, much larger, cyto(endo)skeleton
archaebacteria
oldest type of living organism (not)
eubacteria
a bacterium of a large group typically having simple cells with rigid cell walls and often flagella for movement. The group comprises the “true” bacteria and cyanobacteria, as distinct from archaebacteria.
cell wall
made of peptidoglycan
plasma membrane
also called the cell membrane, is the membrane found in all cells that separates the interior of the cell from the outside environment. In bacterial and plant cells, a cell wall is attached to the plasma membrane on its outside surface.
capsule (bacteria)
large structure common to many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell
active transport
movement against concentration gradient
fluid mosaic model
components of a membrane (proteins or glycolipids) form a mobile mosaic in the fluid-like environment created by a sea of phospholipids
selectively permeable membrane
molecular oxygen, carbon dioxide and other small, nonpolar molecules diffuse across, while large polar molecules cannot move without help
exocytosis
movement of contents of secretory vesicles out of the cell membrane (usually proteins are contained in membrane-bound vesicles)
endocytosis
process by which cell membrane engulfs extracellular material and moves it internally
phagocytosis
cellular “eating”
hypotonic
higher concentration of water outside the cell, cell swells
isotonic
equal concentrations of water inside and outside cell, dynamic equilibrium
osmotic pressure
the force water molecules exert on a membrane when a concentration gradient exists
pinocytosis
cellular “drinking”
Concentration gradient
a form of energy (occurs when a solute is more concentrated in one area than another)
