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What is the cell theory?
- - the cell is the basic structural and functional unit of life
- - organismal activity depends on individual and collective activity of cells
- - function is determined by structure
- - continuity of life has a cellular basis
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Plasma Membrane
- - separates intercellular fluids from extracelluar fluids
- - plays a dynamic role in cellular activity (selectively permeable "picky")
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Fluid Mosaix Model
- - bilayer of phospholipids with embedded, dispersed proteins
- - phospolipids have hydrophobic and hydrophilic portions
- - proteins are peripheral (attached) or integral (through membrane)
- - the membrane also contains choloesterol, glycoproteins, and glycolipids
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What does glyco refer to?
- - sugars attached to the cell
- - the ID of the cell
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What are the functions of membrane proteins
- - transport
- - receptors for signal transduction
- - attachement for cytoskeleton and extracellular matrix
- - enzymatic activity
- - intercellular joining
- - cell to cell recognition
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What are the membrane junctions?
tight junction, desmosome, and gap junction
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What is a tight junction?
impermeable junction that encircles the cell
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What is a desmosome?
anchoring junction scattered along the sides of the cell
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What is a gap junction?
- allows chemical substances pass between cells
- - present in electrically excitable tissue (nervous & mucles)
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Microvilli
- small projections from cell surface which increases surface area
- - cell extension
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Flagella
- long projections used for movement
- - cellular extension
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Cilia
- moves substances in one direction across the cell surfaces
- - cellular extension
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Plasma Membrane Transport
- - requires no energy
- - movement from high concentration areas to low concentration areas
- - filtration
- - simple diffusion
- - facilitated diffusion
- - osmosis
- - osmolarity
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Simple Diffusion
- molecules move directly through the lipid layer
- - small nonpolar and lipid-soluble substances
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Facilitated Diffusion
- - transports glucose, amino acids, and ions
- - will always uses a protein in the process
- - transported substances pass through carrier proteins or protein channels
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Osmosis
- - diffusion of water across a semipermiable membrane
- - occurs when there is a difference in water concentration across the membrane
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Osmolarity
total concentration of solute particles in a solution
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Isotonic
solutions with the same solute concentration
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Hypotonic
solutions having lesser solute concentration
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Hypertonic
solutions having greater solute concentration
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Active Transport
- - requires enegery
- - moves a substance against its will
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Primary Active Transport
- - energy comes from the hydrolysis of ATP
- - uses a protein pump to move molecules
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Secondary Active Transport
- - energy comes from previously established ionic gradient
- - no ATP used in actual transport step
- - when molecule diffuses it drags another molecule with it
- - symport/antiport
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Vesicular Transport
- - for larger polymers
- - membrane-bound vesicles are used to transport material across the membran
- - requires a lot of ATP
- - endocytosis
- - exocytosis
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What is endocytosis?
movement into the cell
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What is exocytosis?
movement out of the cell
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What is cytoplasm?
material between plasma membrane and the nucleus
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What is cytosol?
largely water with disolved proteins, salts, sugars, and other solutes
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Cytoplasmic Organelles
Metabolic machinery of the cell
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Mitochondria
- - double membrane structures with folds called crisae
- - provides most of the cells ATP (energy)
- - contain their own DNA and ribosomes
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Ribosomes
- - site of protein synthesis
- - free ribosomes synthesize soluble proteins
- - membrane-bound (attached) ribosomes synthesize proteins that will be exported
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Endoplasmic Reticulum (ER)
- - interconnect tubes and parallel membranes
- - continuous with the nuclear membrane
- - two varieties - rough ER and smooth ER
- - external surface studded with ribosomes
- - manufactures all secreted proteins
- - responsible for the synthesis of membrane proteins and phospholipids for cell membranes
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Smooth ER
- - tubules arranged in a looping network
- - involved with lipid and cholesterol metabolism
- - also responsible for detoxification of drugs and alcohol
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Golgi Apparatus
- - stacked and flattened membranous sacs
- - functions in modification and packaging of proteins
- - secretory vesicles leave the Golgi apparatus and move to designated parts of the cell
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Lysosomes
- - contains digestive enzymes
- - digest ingested bacteria, viruses, and toxins
- - degrade nonfunctional organelles
- - breakdown non-useful tissue
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Endomembrane System
system of organelles that function: to produce, store, and export biological molecules; degrade potentially harmful substances
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Endomembrane System includes?
system includes nuclear envelope, smooth and rough ER, lysosomes, vacuoles, transport vesicles, Golgi apparatus and the plasma membrane
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Peroxisomes
- - membranous sacs containing oxidases and catalases
- - detoxify harmfil or toxic substances
- - neutralize dangerous free radicals
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What are free radicals?
highly reactive chemicals with unpaired electrons
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Cytoskeletons
- - the skeleton of the cell
- - dynamic, elaborate series of rods running though the cytosol
- - consists of microfilaments, intermediate filaments and microtubules
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Microfilaments
- - smallest fiber
- - contains the protein actin
- - braces and strengthens the cell surface (helps in movement of particles in and out of the cell)
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Intermediate Filaments
- - tough fibers with proteins from the keratin family
- - high tensile strength (rope-like)
- - gives the cell a definite shape and keeps the nucleus in one location
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Microtubules
- - largest fiber
- - hollow tubes made of tubulin
- - determines the overall shape of the cell and distribution or organelles
- - also used to produce cilia and flagella
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Nucleus
- - contains nuclear envelope, nucleoli, and chromatin (DNA)
- - gene-containing control center of the cell (dictates the kinds and amounts of proteins to be synthesized)
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Nuclear Envelope
- - selectively permeable double membrane barrier containing pores
- - pore complex regulates transport of molecules into and out of the nucleus
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Nucleoli
- - dark-staining spherical bodies within the nucleus
- - site of ribosome production
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