Cell Structure

Classification by structure/morphology

	size	nucleus	DNA	organelles	Membrane	division
Prokaryotic (bacteria, archaea)	Small, 1-10 microm	No, nucleoid	Circular strand, unbound in nucleus	Ribosomes in cytosol, none	plasma/cell membrane, cell wall	Binary fission
Eukaryotic (human, plant)	Larger, 10-100 microm	yes	Linear chromosomes	Membrane-bound, mitochondria/chloroplast, parts of endomembrane system, ribosomes in cytosol/membrane bound	Cell membrane (phospholipids), some have cell wall	Mitosis

Common features of cells
Smallest unit, multicellular organisms = cooperative specialized cells
Cell theory: all life made of cells, all cells have 4 common features/same basic structure (plasma membrane--phospholipid bilayer, cytoplasm--semifluid substance, chromosomes--carry genes, made of DNA, ribosomes--make polypeptides, made of RNA), common evolutionary ancestor
Cell size
Plasma membrane is selective barrier: O2, nutrients, waste; SA:V ratio; bigger-compartments/multicellular
Endomembrane system
phospholipid bilayers inside cell: no free ends (closed compartments), separates internal/external, lumen is inside space
Structure is phospholipid bilayer (continuous in 1 long structure), connected via vesicles (transfer membrane segments)
Regulates protein folding/movement; metabolic functions

	structure	function
nucleus	-Surrounding membrane (nuclear envelope)2 membranes: lipid bilayers-Inside lined by nuclear lamina: proteins, maintains nucleus shape and has high security -Transport regulated by nuclear pores-DNA in linear chromosomes (DNA + proteins = chromatin)	Stores genetic info.-Transport regulated by nuclear pores
mitochondria/ chloroplasts	-Similar to prok. Cells, membranes, have own DNA/ribosomes, both surrounded by euk. Membrane	Make ATP -> energy -binary fission
ribosomes	non-membrane bound: not organelles, made of rRNA and proteins-Present in all cells	Synthesize primary polypeptides-free: all cells (mitochondria/chloroplasts)-bound: attached to rough ER
Plasma membrane	All cells surround cell, NOT cell wall,euk. Cell membrane also inside -Amphipathic, fluid	Selectively permeable (reg. what/how much passes through)
Nuclear envelope	Encloses DNA; like membrane	Instruct protein (mRNA) -> nuclear pores -> ribosome -> primary polypeptide
Endoplasmic reticulum	Continuous with nuclear envelope-smooth: no ribosomes	-smooth: metabolizes polysaccharides (breaks down glycogen), detoxifies drugs/poison, stores Ca2+-rough: ribosomes, lumen is internal space-proteins folded/modified, secrete glycoprotein (tell folded proteins where to go), distributes transport vesicles (membrane factory), cell membrane factory
Golgi apparatus	Stacks of membranous sacs are cisternae-Not continuous with ER-cis face: receiving side from ER-trans face: shipping side	Adds sugar tags-modifies ER products, sorts/packages, manufactures macromol., shipping product with transport vesicles
Lysosomes	Sacs of hydrolytic enzymes (cell stomach)-primary: buds off golgi -> no food yet	-food enters in vacuole -> fuses with lysosome and forms secondary (break down complex mol.); stomach of cell
vacuoles	Maintenance compartments, membrane-bound containers from ER/golgi-functions vary per cell	-food: store food-contractile: pump H2O out -central: hold H2O in plants (is larger here)
Nucleolus	makes ribosomes -> RNA/proteins, no membrane; center “sphere”