a tour of the cell every living organism is composed of one or more cells a cell is the smallest...
TRANSCRIPT
A Tour of the Cell
Every living organism is composed of one or more cells
A cell is the smallest unit having the properties of life
The continuity of life directly arises from the growth and division of single cells
Metabolic activity related to cell volume and surface area
Volume increases faster than surface area
The speed and amount of “stuff” (waste & nutrients) across a cell membrane is determined by the surface area
Larger cell volume needs more nutrients and produces more waste
Eventually the cell becomes big enough that the membrane can’t transport “stuff” fast enough
Prokaryotes“Before the nucleus”—
no nucleus or membrane-covered structures (organelles)
BacteriaVery smallSimplest cells
EukaryotesNucleus and other
complex organellesOrganelle—internal
membrane-bound compartment that serves specialized functions. “Little organs”
Nucleoid region DNA (single loop) Cell membrane Cell wall (in some) Capsule (in some) Cytoplasm Ribosomes Pili Flagellum
Most kinds of living organismsProtozoansAlgaeFungiPlantsAnimals
Organelles allow compartmentalizingDifferent areas of the cell can carry on
reactions without affecting the rest of the cell
Complex systems
NucleusControl centerNucleolus
Constructs ribosomesChromatin
All DNA in cell Organized into
chromosomes 6 Feet of DNA in one
nucleus!!!
Nucleus (cont.)Nuclear envelope/membrane
Regulates transport of molecules Receptors for signaling
Nuclear pores Allow communication with cytoplasm
Endoplasmic Reticulum (ER)Rough
Ribosomes attach Protein synthesis
Smooth No ribosomes Lipid synthesis Carbohydrate synthesis
RibosomesSynthesize proteinsOn rough ER
Golgi Body/ApparatusPackage and process proteins & lipids“Warehouse & finishing factory”Receives vesicles from ERProduces vesicles for finished products
Endomembrane system Interconnecting membrane systemNuclear membrane Rough ER Smooth ER
Golgi apparatus lysosomes/vacuoles plasma membrane
Vesicles—sacs containing enzymesLysosomes
Intracellular digestion Destroy bacteria in white blood cells Breaks down damaged organelles
Peroxisomes Break down fatty acids & proteins Detoxify alcohol & other toxic substances
Vacuoles—large vesicles for storing food & waterOnly some eukaryotes
MitochondriaForms ATP (energy) from
carbohydratesRequires oxygenSite of cellular respirationSimilar to bacteria: have
their own DNA & ribosomes May be artifact of ancient
symbiotic relationship between prokaryotes & eukaryotes
PlastidsChlorloplasts
Photosynthesis (energy from light)
Only in plant cellsAmyloplasts
Store starches Specialized chloroplast
Like mitochondria, may be artifact of ancient symbiotic relationship between prokaryotes & eukaryotes
Central VacuoleStorage (amino
acids, sugars, ions, wastes)
Centrioles—produce microfilaments during cell division.
Protein filaments between nucleus & plasma membrane
Internal shape & organization Can be permanent or temporary
Motor proteins move things within cells Flagella—long outer structures for
movementUsually only a few
Cilia—short outer structures for movementUsually many
Pseudopod“False foot”
Structures outside of the plasma membrane
Holds cells together in tissues Protects & supports plasma membrane Collagen
Glycoproteins Strong fibers
Plasma (cell) membraneRegulates movement of “stuff” in and out of
cellPhospholipid bilayer
Animal Cell JunctionsTight junctions
Tight seal, prevents leakage of fluids
Anchoring junctions Rivets Fasten cells together
Gap junctions Channels, pores Allow small molecules
to travel between neighboring cells
Cell-to-cell communication
Nutrient & waste transfer
Cell wallStrong, gives
permanent shape to cell
Bacteria, protists, fungi, plants
Not found in animals
Plasmodesmata Junctions
between plant cell walls
Circulation and communication between cells