Parts of the Cell

Centrosome

microtubule organizing center near nucleus

• forms mitotic spindke during cell division

• contains tubulins that build microtubules in non-dividing cells

centrioles

cylindrical structures, each composed of 9 clusters of microtubular triplets

chromatin

uncondensed DNA in interphase cells

cytoskeleton

determines cell shape and organizes cellular content

• aids movement of organelles

microfilaments

thinnest; generate movement and provide mechanical support

microtubules

largest; determine shape and aid movement

mitotic spindle

separates chromosomes during cell division

asters

visible only when cells are in mitosis

cilia/cilium

contains microtubules; moves fluids along cell’s surface

flagella

moves an entire cell; hair-like

golgi complex

• modifies, sorts, packages, and transports proteins received from the rough ER

  • forms secretory vesicles that discahrge processed proteins via exocytosis into extracellular fluid

microvilli

• nonmotile, finger-like projections of the plasma membrane

  • inc. cell surface area

mitochondria

• site for chemical reactions of aerobic cellular respiration that generate ATP

nucleus

• contains cell’s genes (on chromosomes)

• controls cellular structure

  • directs cellular activities

nuclear envolope

double membrane that separates the nucleus from cytoplasm

nuclear pores

protein-surrounded openings that extend through nuclear envelope

nucleolus

produces ribosomes and rRNA

plasma membrane

membrane made up of lipid bilayer separating the interior of a cell from the outside environment

• facilitates exchange of subtances in and out the cell

ribosomes

• function: protein synthesis

• may be free in cytosol or attached to rough ER

rough endoplasmic reticulum

• membranous network of flattened sacs/tubules covered by ribosomes

• attached to nuclear envelope

  • synthesizes glycoproteins and phospholipids that are transferred to organelles, inserted into plasma mebrane, or secreted during exocytosis

smooth endoplasmic reticulum

• membranous network of flattened sacs or tubules that lacks ribosomes

• synthesizes fatty acids and steroids

• inactivates/detoxifies drugs

• stores and releases Ca+ ions in muscle cells

golgi complex

mitochondria

nucleus

smooth ER (left) rough ER (right)