cells part 1 Flashcards
cell theory
1) cells are the fundamental unit of life
2) all organisms are composed of cells
3) all cells come from preexisting cells
4) modern cells evolved from a common ancestor
surface area-to-volume ratio
-as cell volume increases, chemical activity increases, along with the need for resources and waste removal
-the larger the surface area, the smaller the volume. the larger the volume, the smaller the surface area
-because resources and waste come in and out through the membrane, surface area becomes limiting.
light microscopes
glass lenses and light
electron microscopes
electromagnets focus an electron beam
the cell membrane
-permeable barrier
-allows cells to maintain a constant internal environment
-is important in communication and receiving signals
-often has proteins for binding and adhering to adjacent cells
prokaryotic cells
(bacteria and archaea): have no membrane-enclosed internal compartments
eukaryotic cells
(Eukarya): have membrane-enclosed organelles in which different functions occur
features of all prokaryotic cells
-enclosed by a cell membrane
-DNA located in a region called nucleoid
-cytoplasm
-ribosomes
cytoplasm
the rest of the cell contents
ribosomes
sites of protein synthesis, ribosomes float in the cytoplasm
nucleoid
where DNA is located
capsule
-filled with polysaccharides which help them adhere to things
-protect them from drying out
-protect them from a host’s immune system
pili
hairlike structures projecting from the cell surface, help bacteria adhere to other cells
flagella
how prokaryotes swim, made of the protein flagellin
cell wall
outside the cell membrane
