eukaryotic cells

principle parts of a cell: cell (plasma) membrane

separates the intracellular & extracellular compartments; selectively permeable; provides some structure

principle parts of a cell: cytoplasm

gel-like internal environment of the cell

principle parts of a cell: organelles

subcellular structures within the cytoplasm; perform specific functions

principle parts of a cell: nucleus

contains the cell’s DNA

cell membrane is composed primarily of phospholipids & proteins

the phospholipids can form a bilayer which restricts the passage of water & water-soluble molecules & ions

cell membrane proteins provide specific functions

transporters, channels, receptors, enzymes

exocytosis

out of the cell

endocytosis

into the cell

endocytosis: phagocytosis

surround & engulf particles; white blood cells & macrophages

endocytosis: pinocytosis

cell membrane invaginates, fuses together & then pinches off, entering the cell

associated cell membrane structures: cilia

tiny, hairlike structures that protrude from the cell; coordinated movement

cilia: respiratory system

transport strands of mucus out of the lungs

cilia: female reproductive tract

moves the egg to the uterus

associated cell membrane structures: flagellum

single whip-like structure that propels the sperm cell through its environment

associated cell membrane structures: microvilli

numerous tiny folds in the cell membrane increase surface area (diffusion)

cytoplasm

jelly-like matrix within a cell excluding the nucleus; highly organized structure

cytoskeleton

actin, microtubules, and intermediate filaments function as a cytoskeleton; flexible structure that allows movement & reorganization

organelles: lysosomes

membrane bound organelles that contain digestive enzymes; fuse with food vacuoles to digest products of endocytosis; lysosomes play an important role in both apoptosis & autophagy

apoptosis

program cell death; the removal of old or damaged cells from the body

autophagy

intracellular degradation; cells recycle organelles & macromolecules to generate energy

organelles: mitochondria

most cells contain hundreds to thousands of these organelles; mitochondria play an important role in the production of energy for the cell

organelles: peroxisomes

contain enzymes involved in oxidation reactions; toxins are oxidized to produce less harmful intermediates (like H2O2); particularly important in liver & kidney cells

organelles: rough endoplasmic reticulum

contains ribosomes; important role in protein synthesis

orgnaelles: smooth endoplasmic reticulum

storage of Ca2+ (calcium ions) in striated muscle cells; sarcoplasmic reticulum

organelles: golgi apparatus

packages molecules for secretion from the cell; routes newly synthesized proteins to appropriate cellular compartment