Cell parts

centrosomes

Location: perinuclear cytoplasm

assists in the formation and organization of microtubules. It is responsible for spindle formation during mitosis.

Free ribosome

location: cytoplasm

polyribosomes represent sites of cytoplasmic protein synthesis

Golgi apparatus

Location: cytoplasm, adjacent to rough endoplasmic reticulum

transport vesicles, containing newly synthesized proteins from the RER

Lysosome

Location: cytoplasm

Digest macromolecules, microorganisms, old or damaged organelles

Membrane-bound ribosomes

Location: outer aspect of RER, outer aspect of outer nuclear envelope

involved in translating protein destined for secretory vesicles, lysosomes, or insertion into membranes

Mitochondrion

Location: cytoplasm

The “powerhouse” of the cell. Synthesizes ATP which provides chemical energy used for cellular respiration

nucleolus

Location: nucleus

Ribosomal RNA synthesis and ribosome synthesis

nucleus

Location: generally located in the cell, sometimes it is off to one side

DNA replication, DNA transcription into mRNA, and ribosomal RNA synthesis and ribosomal subunit assembly (in nucleolus)

Plasma membrane

Location: Cell surface

Encloses cell contents, communication, intercellular connections, and it regulates the movement of materials into and out of the cell

Rough endoplasmic reticulum (RER)

Location: Cytoplasm (perinuclear), between the nucleus and the Golgi apparatus

synthesizes protein for secretion, insertion into plasma membrane, and lysosomal enzymes and other protein packages in vesicles

Smooth endoplasmic reticulum (SER)

Location: cytoplasm

synthesizes lipids, detoxifies drugs and alcohol, metabolizes carbohydrates, and stores calcium

cholesterol molecules in lipid bilayer

location: hydrophobic region of the lipid bilayer or plasma membrane

strengthens membrane and stabilizes it at extreme temperatures, prevents over dense packing of fatty acid tails by filling the gaps between fatty acid tails

fatty acid tails of lipid bilayer

Location: hydrophobic region of the lipid bilayer of plasma membrane

length and saturation of the fatty acid tails influence fluidity and flexibility of membrane

integral membrane protein

Location: plasma membrane

receptors for specific molecules, enzyme activity, membrane channel, cell-identity marker, and cell adhesion

Lipid Bilayer

Location: plasma membrane, membrane-bound organelles

forms semipermeable membrane around cells and membrane-bound organelles, separates aqueous intracellular and extracellular compartments, and membrane surface charge

Membrane channel protein

Location: plasma membrane

permits selective passage of water and hydrophilic solutes, some channels constantly open, other channels open with specific stimulus

Peripheral membrane protein

Location: plasma membrane

cell signaling, regulation of transmembrane proteins, enzyme activity

Polar heads of lipid bilayer

Location: hydrophilic region of lipid bilayer of plasma membrane

membrane surface charge, intracellular signaling