Structure |
Cytoplasmic Organelles |
Description |
|
Plasma membrane |
Membrane boundary of living cell |
Endoplasmic reticulum (ER) |
Network of internal membranes extending through cytoplasm |
Smooth endoplasmic reticulum |
Lacks ribosomes on the outer surface |
Rough endoplasmi reticulum |
Ribosomes stud outer surface |
Ribosomes |
Granules composed of RNA and protein; some attached to ER and some are free in cytosol |
Golgi complex |
Stacks of flattened membrane sacs |
Lysosomes |
Membranous sacs (in animals) |
Vacuoles |
Membranous sacs (mostly in plants, fungi, and algae) |
Microbodies (e.g., peroxisomes) |
Membranous sacs containing a variety of enzymes |
Mitochondria |
Sacs consisting of two membranes; inner membrane is folded to form cristae and encloses matrix |
Plastids (e.g., chloroplasts) |
Double membrane structure enclosing internal thylakoid membranes; chloroplasts contain chlorophyll in thylakoid membranes |
The Cytoskeleton |
|
Microtubules |
Hollow tubes made of subunits of tubulin protein |
Microfilaments |
Solid, rod-like structures consisting of actin protein |
Centrioles |
Pair of hollow cylinders located near center of cell; each centriole consists of nine microtubule triplets (9 × 3 structure) |
Cilia |
Relatively short projections extending from surface of cell; covered by plasma membrane; made of two central and nine peripheral microtubules (9 2 structure) |
Flagella |
Long projections made of two central and nine peripheral microtubules (9 2 structure); extend from surface of cell; covered by plasma membrane |