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Cell Transport

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Page 1: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Cell Transport

Page 2: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Ch. 9: Cell Transport Passive Transport Targets

Distinguish between diffusion & osmosis Define equilibrium & explain how it is

established Explain what is meant by a concentration

gradient Explain how substances cross the cell

membrane through facilitated diffusion Explain how ion channels assist the diffusion

of ions across the cell membrane

Page 3: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Concentration

how much of a given substance there is mixed with another substance

Page 4: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Kinetic Motion

All particles of matter are in constant (random) motion

Molecules travels in a straight line until they hit something, bounce off, and travel in a new direction

Molecules move down the concentration gradient from an area more concentrated to an area less concentrated

Page 5: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Concentration Gradient Difference in concentration of a substance

across a space

Page 6: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Types of Cellular Transport

Passive Transport cell doesn’t use energy

1. Diffusion2. Facilitated Diffusion3. Osmosis

Active Transportcell does use energy

1. Protein Pumps2. Endocytosis3. Exocytosis

high

low

This is gonna

be hard work!!

high

low

Weeee!!!

• Animations of Active Transport

& Passive Transport

Page 7: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Passive Transport Diffusion

- Movement of molecules from an area of higher concentration to an area of lower concentration

- Driven entirely by the kinetic motion of molecules

- Continues until the concentration of molecules is the same throughout the space they occupy

Page 8: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Factors Affecting Diffusion Rate

Page 9: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Equilibrium

Exists when the concentration of the molecules of a substance is the same throughout a space

Random motion of molecules continues so equilibrium is maintained (no concentrated gradient)

Page 10: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Diffusion Across Membranesright guard commercial

Cell membranes are selectively permeable Phospholipid bilayer (non-polar)

Diffusion depends on size, type of molecule, & chemical nature of molecule

Page 11: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

3. Structure of cell membrane

Lipid Bilayer -2 layers of phospholipidsa. Phosphate head is polar (water loving)

b. Fatty acid tails non-polar (water fearing)

c. Proteins embedded in membrane

About Cell Membranes (continued)

Phospholipid

Lipid Bilayer

Page 12: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between
Page 13: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Diffusion Across Membranes Non-polar molecules

(O2 & CO2) can dissolve in lipid bilayer and thus pass through by diffusion

Very small insoluble molecules may pass through membrane pores by diffusion

Large or Polar substances move through membrane with help from transport proteins as do ions

Page 14: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between
Page 15: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Osmosis Osmosis Diffusion of water molecules

through a cell membrane from an area of higher water molecule concentration to an area of lower concentration

Quick Fact! Process of osmosis was first

described in 1748 by French scientist Abbé Jean Antoine Nollet. He observed that water spontaneously diffused through a pig bladder membrane into alcohol!

Page 16: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Direction of Osmosis

Depends upon the relative concentration of solutes on the two sides of the membrane

Page 17: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Osmotic Potential

The tendency of water to move across a membrane into a solution

The lower the solute concentration, the higher the osmotic potential

Page 18: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Isotonic Solution A solution in which the concentration of

dissolved substances is the same as the concentration inside the cell; therefore, the concentration of water is the same on both sides of the plasma membrane

Diffusion of water in = water out

Page 19: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Turgor Pressure

Pressure that exists inside a cell

Page 20: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Hypotonic Solution A solution in which the concentration

of a dissolved substance is lower than the concentration inside the cell; therefore, the concentration of water is greater outside the cell than inside the cell

Water diffuses into the cell & the cell swells-Turgor Pressure increases

Cytolysis – cell bursts Plant v. Animal

Page 21: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Osmosis (Cell in Hypotonic Solution

Page 22: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Hypertonic Solution

A solution in which the concentration of dissolved substances is higher than the concentration inside the cell; the concentration of water is greater in the cell than outside Result: water moves out of the cell & the

turgor pressure decreases & the cell shrivels

Plasmolysis – loss of water pressure in a cell

Page 23: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Osmosis (Cell in Hypertonic Environment)

Page 25: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

How Cells Deal with Osmosis

Example: Paramecia (freshwater protozoan) Live in a hypotonic environment Water constantly diffuse into them Contractile vacuoles (organelle) removes the excess

water A common remedy for a sore throat is to gargle

with salt water. Using the concept of osmosis, explain how this remedy might work.

Quick Fact! Wooden drawers in cabinets absorb water from the

air on humid days causing the wood to swell & hard to open!

Page 26: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Osmotic Pressure

Pressure required to stop osmosis in a solution- Pressure that builds up as water diffuses into

a cell- If a physical barrier prevents expansion of

a hypertonic solution as water moves in by osmosis, a buildup of pressure is created as water continues to flow in- As pressure ↑, the net flow of water molecules will

slow (stops in plants due to cell wall – turgor pressure)

Page 27: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Reverse Osmosis

The movement of water particles from an area of lower concentration to an area of higher concentration with the

Addition of pressure

Page 28: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Facilitated Diffusion Used for molecules that cannot

diffuse rapidly across the membrane (size, polarity)

Molecules are assisted by membrane proteins

2 Types Carriers & Channels Move down the concentration

gradient (High [ ] to low [ ]) no energy is used by cell

Page 29: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Facilitated Diffusion Molecule binds to carrier protein Protein changes shape shielding molecule

from lipids as it crosses Molecule is released to cell interior Carrier protein returns to original shape

Accelerates glucose movement Carrier proteins are specific to the

molecules they carry

Page 30: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Facilitated Diffusion

Carriers Channels

Page 31: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Diffusion through Ion Channels

Membrane proteins Passageway through membrane for ions to

pass through (Na+, Ca2+, Cl-) Each ion channel is specific to one type of ion Some channels are always open, others have

gates Gates open in response to stimuli

1. Stretching of cell membrane2. Electrical signals3. Chemical signals

Page 32: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Ion Channels

Page 33: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Active Transport

Differentiate between active & passive transport

Compare & contrast endocytosis & exocytosis

Page 34: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Active Transport

Movement of materials up a concentration gradient, from an area of low concentration to an area of higher concentration

Requires cell to use energy Uses carrier proteins [ ] = Concentration

Page 35: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Active Transport

Endocytosis & Exocytosis

Transport of macromolecules & food particles too large to pass to pass through cell membrane

Page 36: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Endocytosis

Process by which cells ingest large materials by surrounding them with the cell membrane forming a pouch

Pouch pinches off from membrane & forms a vesicle

Page 37: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Endocytosis

Types: Pinocytosis

Transports solutes or fluids (cell drinking)

Page 38: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Endocytosis Phagocytosis

Ingestion large particles or whole cells (cell eating) Many unicellular organisms feed this way Used to ingest bacteria & viruses Cells called phagocytes – allows lysosomes to fuse with vesicles

containing bacteria & viruses to destroy them

Page 39: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Exocytosis Reverse of endocytosis Cell excretion Vesicles in cytoplasm fuse with cell membrane to

release contents to external environment Releases proteins packaged in Golgi apparatus

Page 41: Cell Transport. Ch. 9: Cell Transport Passive Transport Passive Transport Targets Targets Distinguish between diffusion & osmosis Distinguish between

Kidspiration by: Riedell