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 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 CELL BOUNDARIES

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.Lipid B.Carbohydrate C.Protein D.Nucleic Acid

What biomolecule Serve as channels & pumps for transport A.Lipid B.Carbohydrate C.Protein D.Nucleic Acid

What biomolecule is used to to identify as “self or non-self” A.Lipid B.Carbohydrate C.Protein D.Nucleic Acid

Non-polar tail, found in the middle of cell membrane A.a B.b C.c D.d E.e [Default] [MC Any] [MC All]

Embedded in cell membrane, serve as channels & pumps A.a B.b C.c D.d E.e [Default] [MC Any] [MC All]

Polar portion of cell membrane oriented towards water A.a B.b C.c D.d E.e [Default] [MC Any] [MC All]

Provides stability for animal cell membrane A.a B.b C.c D.d E.e

Serve as “id” tags for cell A.a B.b C.c D.d E.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 (single- celled 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.Active transport B.Diffusion C.Endocytosis D.Exocytosis E.Facilitated Diffusion F.Osmosis G.Passive Transport H.Protein Pump

Requires energy in the form of ATP A.Active transport B.Diffusion C.Endocytosis D.Exocytosis E.Facilitated Diffusion F.Osmosis G.Passive Transport H.Protein Pump

cell sucking in or eating A.Active transport B.Diffusion C.Endocytosis D.Exocytosis E.Facilitated Diffusion F.Osmosis G.Passive Transport H.Protein Pump

Diffusion of specific molecules through a protein channel A.Active transport B.Diffusion C.Endocytosis D.Exocytosis E.Facilitated Diffusion F.Osmosis G.Passive Transport H.Protein Pump

Diffusion of water through a selectively permeable membrane A.Active transport B.Diffusion C.Endocytosis D.Exocytosis E.Facilitated Diffusion F.Osmosis G.Passive Transport H.Protein Pump [Default] [MC Any] [MC All]

Movement of molecules from high concentration to low, does NOT require energy A.Active transport B.Diffusion C.Endocytosis D.Exocytosis E.Facilitated Diffusion F.Osmosis G.Passive Transport H.Protein Pump

Movement of ions and molecules against the concentration gradient, requires energy A.Active transport B.Diffusion C.Endocytosis D.Exocytosis E.Facilitated Diffusion F.Osmosis G.Passive Transport H.Protein Pump

Cell spitting out or pooping A.Active transport B.Diffusion C.Endocytosis D.Exocytosis E.Facilitated Diffusion F.Osmosis G.Passive Transport H.Protein Pump