Organelles

plasma membrane

structure: phospholipid bilayer containing cholesterol, proteins (integral and peripheral), and some carbohydrates (externally)

function: contains receptors for communication, forms intercellular connections, acts as physical barrier to enclose cell contents, regulates material movement into and out of the cell

cytoplasm

structure: consists of cytosol (fluid portion) and organelles

function: place of many metabolic processes of the cell, stores nutrients and dissolved solutes

nucleus

structure: surrounded by double membrane nuclear envelope (each membrane is a phospholipid bilayer), contains nucleolus and chromatin within nucleoplasm (a fluid)

function: acts a cell control center, houses genetic information (DNA), site of ribosome subunit assembly

proteins

scattered within membrane and some are attached, others “float”

cholesterol

strengthens membrane

glycocalyx

carbohydrates that participate in cell to cell recognition

microvilli

increase membrane surface area for increased absorption or secretion

cilia

larger, hairlike projection (larger than microvilli) and move substances over cell surface

mitochondria

structure: double membrane structures with cristae, fluid matrix contents at center, contains its own DNA called mtDNA

function: make ATP and contain their own DNA inherited from oocyte (egg) because head of sperm contains no mitochondria

ribosomes

spherical structures involved in protein synthesis

free ribosomes

primarily make proteins for the cell itself

bound ribosomes

make proteins for plasma membrane or proteins to be exported outside cell

rough endoplasmic reticulum

has ribosomes on walls, synthesizes and distributes proteins

smooth endoplasmic reticulum

has no ribosomes, synthesizes lipids (especially steroid hormones), detoxifies drugs, alcohol, poisons

golgi apparatus

structure: flattened, smooth sacs with small “vesicles”

function: accepts, sorts, packages materials from rough ER, common in secretory cells

lysosomes

structure: spherical digestive enzymes

function: digest materials or microbes ingested by cell, remove old/damaged organelles, self destructs (autolyze)

Tay-Sachs disease (inherited disorder, lysosomal enzyme missing of dysfunction, buildup of waste in cells, including nerve cells)

centrioles

pair of rod-shaped structures involved in cell division

nucleolus

structure: spherical, dark-staining, dense granular region in the nucleus

function: synthesizes rRNA and assembles ribosome subunits