FLEXIBLE, SELECTIVELY PERMEABLE boundary that helps control what enters and leaves the cell. Composed of: a. Two layers of PHOSPHOLIPIDS molecules

Transcription

1 FLEXIBLE, SELECTIVELY PERMEABLE boundary that helps control what enters and leaves the cell. Composed of: a. Two layers of PHOSPHOLIPIDS molecules arranged with POLAR HEADS facing outside and NON-POLAR TAILS facing the inside. b. Proteins and carbohydrates. Q: What model do we use to describe the plasma membrane?

2 The phospholipid components are free to move laterally (side-by-side) with proteins and carbohydrates forming patterns IN and ON the bi-layer. Membranes Animations - CMU Modern Biology Fluid Mosaic Model

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4 CELL TRANSPORT The Movement of Compounds Across the Cell Membrane PASSIVE TRANSPORT DIFFUSION FACILITATED DIFFUSION OSMOSIS ACTIVE TRANSPORT CARRIER PROTEINS ENDOCYTOSIS EXOCITOSIS

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6 PASSIVE TRANSPORT CONCENTRATION GRADIENT Difference of concentration between two sides of a membrane. ACTIVE TRANSPORT ENERGY ATP Cell Energy Packet Cell Energy Currency

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8 A Concentration Gradient is the DIFFERENCE in concentration between one side of a cell membrane and the other.

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10 DO YOU REALLY WANT TO KNOW? Here You Go ADENOSINE TRI-PHOSPHATE A.K.A. (Forget about the fancy stuff & remember the short one!)

11 It is the transport of solute from the side of HIGHER concentration of a semipermeable membrane to the side of LOWER concentration. (WITH Gradient) Diffusion

12 It is the transfer of SOLUTE through CARRIER PROTEINS found EMBEDDED in the membrane, from the side of HIGHER to the side of LOWER concentration. (WITH Gradient) Facilitated Diffusion Proteins involved in Facilitated Diffusion

13 Facilitated Diffusion Animation from:

14 It s the passage of water across a SEMIPERMEABLE MEMBRANE from an area of HIGH concentration to an area of LOW concentration. The process continues until the SAME concentration is reached on both sides of the membrane (EQUILIBRIUM) It s like DIFFUSION but for WATER ONLY.

15 It s the diffusion of WATER, though a semipermeable membrane, from the side with LOWER concentration of SOLUTE (the stuff in the water) to the side with HIGHER concentration of it. Osmosis

16 IMAGE by RIEDELL OSMOSIS = SPECIAL KIND OF DIFFUSION OSMOSIS DIFFUSION See osmosis animation Movement of molecules across a Semi-permeable membrane from Higher concentration to lower

17 Animation: See an animation Osmosis1

18 The NET DIRECTION of osmosis depends on the RELATIVE concentration of solutes on the two sides of the membrane. Net Direction of Osmosis

19 Animation from: OSMOSIS See an animation OSMOSIS 4 HYPERTONIC: Concentration of solutes outside cell is inside cell GREATER THAN More water leaves cell than enters so cell shrinks

20 Cell in Hypertonic Solution 15% NaCL 85% H 2 O ENVIRONMENT CELL 5% NaCL 95% H 2 O What is the direction of water movement?

21 Animation from: OSMOSIS See an animation Osmosis3 HYPOTONIC: Concentration of solutes outside cell is inside the cell LESS THAN More water enters than leaves cell so cell will Swell and possibly burst

22 Cell in Hypotonic Solution 10% NaCL 90% H 2 O CELL 20% NaCL 80% H 2 O What is the direction of water movement?

23 OSMOSIS ISOTONIC: Concentration of solutes outside cell EQUALS concentration inside cell Water entering = water leaving so cell STAYS THE SAME SIZE

24 Cell in Isotonic Solution 10% NaCL 90% H 2 O ENVIRONMENT CELL 10% NaCL 90% H 2 O NO NET MOVEMENT What is the direction of water movement? The cell is at. equilibrium

25 Isotonic Solution Concentration of solutes is equal inside and out Hypotonic Solution Concentration of solutes outside is less than inside Hypertonic Solution Concentration of solutes outside is greater than inside

26 Isotonic Solution NO NET MOVEMENT OF H 2 O (equal amounts entering & leaving) Hypotonic Solution Cell Swells & may burst Hypertonic Solution Cell shrivels up

27 Animal cells

28 Osmosis in Red Blood Cells Isotonic Hypotonic Hypertonic

29 Plant cells CELL WALL keeps Plant cells from bursting

30 VACUOLES store WATER OSMOTIC (turgor) PRESSURE = Pressure exerted by water during osmosis

31 SO WHAT? Bath water is hypotonic compared to you Sitting in the bathtub causes your fingers and toes to wrinkle up when water enters your skin cells by osmosis

32 Grocery stores spray water on their veggies to plump them up

33 It is the transport of solute by CARRIER PROTEINS, from the side of a semipermeable membrane with LOWER concentration to the side with HIGHER concentration. (AGAINST Gradient) It requires ENERGY in order to take place. THREE KINDS 1. Carrier Proteins 1. Endocytosis 1. Exocytosis

34 Carrier proteins or Pumps are found EMBEDDED in the cell membrane and transport molecules across it. These proteins are used to move SMALL MOLECULES (Calcium, Potassium, & Sodium) Sodium Potassium Pump (only animation) Sodium Potassium Pump

35 ENDO INSIDE Processes by which the cell TAKES IN LARGE particles by ENGULFING them in a VESICLE formed by the cell membrane which folds into itself to form a pouch. The pouch separates from the membrane and continues on.

36 EXO OUTSIDE Processes by which the cell GETS RID of LARGE PARTICLES through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out of the cell.

37 ENDOCYTOSIS & EXOCYTOSIS Can You tell Me Which One Is Which? Endocytosis & Exocytosis Animation

38 For a Quick Review, See: Cell Transport Recap