| Structure |
Description |
| Cell Nucleus |
|
| Nucleus |
Large structure surrounded by double membrane |
| Nucleolus |
Special body within nucleus; consists of RNA and protein |
| Chromosomes |
Composed of a complex of DNA and protein known as chromatin; resemble rod-like structures after cell division |
| Cytoplasmic Organelles |
|
| 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 endoplasmic 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 x 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 |
