UNIT 4 CELL BOUNDARIES AND TRANSPORT CELL BOUNDARIES
UNIT 4 CELL BOUNDARIES AND TRANSPORT
CELL BOUNDARIES Cell Wall • Outermost boundary of some cells – In plants composed of cellulose – In fungi composed of chitin – In bacteria, Eubacteria composed of peptidoglycan – In some Protist not all • Provide structure & support • Does NOT regulate what enters & leaves the cell.
CELL BOUNDARIES Cell Membrane • • Surrounds every cell Maintains homeostasis Protective barrier between cell & its environment Selectively permeable – Only allows certain things to enter & exit the cell – Also called a plasma membrane • Hydrophilic Head • Not a fixed sheet of molecules, but a fluid structure • Composed of three biomolecules: lipids, carbohydrates, & proteins
LIPIDS Two Types • Phospholipid bilayer o Function is to regulate what can enter or leave the cell w/o a channel or pump o polar phosphate heads (facing toward the inside & outside of the cell) o non-polar fatty acid tails (facing towards each other) • Cholesterol o cell membranes of animal cells ONLY (because no cell wall) o Provides stability for the cell o non-polar located between the fatty acid tails •
CARBOHYDRATES • On the outside of the cell membrane to identify as “self or non-self”
PROTEINS • Embedded in the bilayer • Serve as channels & pumps for transport of specific molecules across the cell membrane
What biomolecule regulate what can enter or leave the cell w/o a channel or pump? A. B. C. D. Lipid Carbohydrate Protein Nucleic Acid
What biomolecule Serve as channels & pumps for transport A. B. C. D. Lipid Carbohydrate Protein Nucleic Acid
What biomolecule is used to to identify as “self or non-self” A. B. C. D. Lipid Carbohydrate Protein Nucleic Acid
Non-polar tail, found in the middle of cell membrane A. B. C. D. E. a b c d e [Default] [MC Any] [MC All]
Embedded in cell membrane, serve as channels & pumps A. B. C. D. E. a b c d e [Default] [MC Any] [MC All]
Polar portion of cell membrane oriented towards water A. B. C. D. E. a b c d e [Default] [MC Any] [MC All]
Provides stability for animal cell membrane A. B. C. D. E. a b c d e
Serve as “id” tags for cell A. B. C. D. E. a b c d e [Default] [MC Any] [MC All]
CELL TRANSPORT Passive Transport • Does NOT require energy • Movement of substances from a high concentration to low • 3 Types: o Diffusion o Facilitated diffusion o Osmosis
DIFFUSION Diffusion: • Random movement of molecules in a liquid or gas • Example: odor gradually fills a room
FACILITATED DIFFUSION Facilitated Diffusion: • Diffusion of specific molecules through a protein channel • Ex: glucose as it is transported across a cell membrane by a protein channel
OSMOSIS Osmosis: • Diffusion of water through a selectively permeable membrane • Can create osmotic pressure if that happens than the cell can swell and burst • How to control Osmotic Pressure: o Cell wall - Physically prevents cell from expanding o Contractile vacuole- pumps water out of cell (singlecelled organisms without cell walls) o Blood- is mostly water to equalize osmotic pressure
• Water will tend to move across the membrane until equilibrium is reached. • At that point, the concentrations of water and sugar will be the same on both sides of the membrane. • Isotonic- the two solutions gain Equilibrium • Hypertonic- “above strength, ” (more sugar than water) so the cell is Wilted or shriveled • Hypotonic- “below strength. ” (more water than sugar) so the cell is Bloated or expanded
ACTIVE TRANSPORT Requires energy in the form of ATP 3 types: • Protein Pumps • Endocytosis • Exocytosis
PROTEIN PUMPS Protein Pumps: • Movement of ions and small molecules against the concentration gradient • low concentration to high concentration
ENDOCYTOSIS AND EXOCYTOSIS Endocytosis: • “Sucking In” or Cell Eating • Cell membrane surrounds and engulfs particles • Example: white blood cells engulfing bacteria and other pathogens Exocytosis • “ Spitting Out ” or Cell pooping • Release large amounts of material • Vesicles containing substances move to cell membrane fuse with it, then expel • Example: secretion of hormones
ENDOCYTOSIS AND EXOCYTOSIS
Random movement of molecules in a liquid or gas A. B. C. D. E. F. G. H. Active transport Diffusion Endocytosis Exocytosis Facilitated Diffusion Osmosis Passive Transport Protein Pump
Requires energy in the form of ATP A. B. C. D. E. F. G. H. Active transport Diffusion Endocytosis Exocytosis Facilitated Diffusion Osmosis Passive Transport Protein Pump
cell sucking in or eating A. B. C. D. E. F. G. H. Active transport Diffusion Endocytosis Exocytosis Facilitated Diffusion Osmosis Passive Transport Protein Pump
Diffusion of specific molecules through a protein channel A. B. C. D. E. F. G. H. Active transport Diffusion Endocytosis Exocytosis Facilitated Diffusion Osmosis Passive Transport Protein Pump
Diffusion of water through a selectively permeable membrane A. B. C. D. E. F. G. H. Active transport Diffusion Endocytosis Exocytosis Facilitated Diffusion Osmosis Passive Transport Protein Pump [Default] [MC Any] [MC All]
A. B. C. D. E. F. G. H. Movement of molecules from high concentration to low, does NOT require energy Active transport Diffusion Endocytosis Exocytosis Facilitated Diffusion Osmosis Passive Transport Protein Pump
A. B. C. D. E. F. G. H. Movement of ions and molecules against the concentration gradient, requires energy Active transport Diffusion Endocytosis Exocytosis Facilitated Diffusion Osmosis Passive Transport Protein Pump
Cell spitting out or pooping A. B. C. D. E. F. G. H. Active transport Diffusion Endocytosis Exocytosis Facilitated Diffusion Osmosis Passive Transport Protein Pump
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