Transport of Materials into and out of Cells

Types of Cell Boundaries Permeable allows a substance to cross Impermeable does not allow a substance to cross Semipermeable or Selectively Permeable allows some but not all substances to cross cell membranes are selectively permeable

Transporting Materials there are two major types of ways that materials are transported into or out of cells they primarily differ on whether or not they use energy Passive Transport Active Transport

Passive Transport movement across a cell membrane that does not require a cell to use energy Diffusion Osmosis

Diffusion the movement of a substance down a concentration gradient caused by the random motion of particles of the substance concentration gradient – a difference in the concentration of a substance across a space down a concentration gradient means from an area of high concentration to an area of lower concentration Click Here

Diffusion if diffusion is allowed to continue, equilibrium eventually results equilibrium – a condition in which the concentration of a substance is equal throughout a space

Diffusion there are two major types of diffusion they primarily differ on whether or not the molecule passes through the phospholipid bilayer or through a channel protein Simple Diffusion Facilitated Diffusion

Simple Diffusion diffusion directly through the phospholipid bilayer molecules like O2 and CO2 that are VERY SMALL AND NONPOLAR can diffuse across the phospholipid bilayer molecules move down a concentration gradient so simple diffusion requires no energy (passive transport)

Facilitated Diffusion diffusion across a cell membrane through a membrane protein channel SMALL polar AND ionic substances like sugar and salt can’t cross the phospholipid bilayer because they cannot pass through the nonpolar lipid tails also moves molecules down a concentration gradient so facilitated diffusion requires no energy (passive transport) Click Here (watch sections 3-7)

Simple Diffusion vs. Facilitated Diffusion Name one similarity and one difference of simple diffusion and facilitated diffusion.

Similarities Both diffusion Passive transport No energy used Down a concentration gradient From high to low concentration Only moves small substances

Differences Simple Facilitated Moves nonpolar substances Moves substances directly through the phospholipid bilayer Facilitated Moves polar substances and ionic substances (substances with charges) Moves substances through a channel membrane protein

Osmosis diffusion of water through a selectively permeable membrane down its concentration gradient because water is moving from high to low concentration, osmosis requires no energy (passive transport)

Osmosis osmosis occurs through special channel proteins called aquaporins “aqua” water “pore” hole “in” protein

Osmosis

Beaker Conditions Compared to the Cell Hypotonic Hypertonic Isotonic Before Beaker Sucrose % Compared to the Cell Sucrose % Beaker Water % Compared to the Cell Water %

Beaker Conditions Compared to the Cell Hypotonic Hypertonic Isotonic Before Beaker Sucrose % Compared to the Cell Sucrose % Low Beaker Water % Compared to the Cell Water % High

Beaker Conditions Compared to the Cell Hypotonic Hypertonic Isotonic Before Beaker Sucrose % Compared to the Cell Sucrose % Low High Beaker Water % Compared to the Cell Water %

Beaker Conditions Compared to the Cell Hypotonic Hypertonic Isotonic Before Beaker Sucrose % Compared to the Cell Sucrose % Low High Equal Beaker Water % Compared to the Cell Water %

Beaker Conditions Compared to the Cell Hypotonic Hypertonic Isotonic After Why was there a change (or no change) in cell size?

Beaker Conditions Compared to the Cell Hypotonic Hypertonic Isotonic After Why was there a change (or no change) in cell size? Water moved into the cell.

Beaker Conditions Compared to the Cell Hypotonic Hypertonic Isotonic After Why was there a change (or no change) in cell size? Water moved into the cell. Water moved out of the cell.

Beaker Conditions Compared to the Cell Hypotonic Hypertonic Isotonic After Why was there a change (or no change) in cell size? Water moved into the cell. Water moved out of the cell. Water moved into and out of the cell at the same rate.

How Osmosis Works Video Click Here!

Osmosis Simulation Click Here!

Active Transport any movement of a substance across a cell membrane that requires a cell to use energy

Active Transport there are two major types of active transport they differ on two factors size of the molecule being moved concentration of the molecule being moved Protein Pumps Bulk Transport

Protein Pumps protein pumps spend energy to move molecules through the cell membrane molecules are moved against the concentration gradient molecules move from low to high concentration

Protein Pumps cells use a special molecule called ATP for energy

Different Types of Proteins How are the proteins used in facilitated transport different (functionally) from the protein pumps used in active transport? Active transport protein pumps use energy to move materials against a concentration gradient. Facilitated diffusion proteins only serve as an opening for diffusion to occur (using no energy) from high to low concentration. How are the proteins used in facilitated transport similar(functionally) from the protein pumps used in active transport? Both allow substances to cross the cell membrane.

Bulk Transport cells use phospholipid membrane bound pouches called vesicles to move macromolecules too large to fit through any openings in the cell membrane

Bulk Transport vesicle an organelle used to transport materials into a cell, out of a cell, or within a cell made of a phospholipid bilayer

What else is made of a phospholipid bilayer? Cell (plasma) membranes!!!

Bulk Transport vesicle an organelle used to transport materials into a cell, out of a cell, or within a cell made of a phospholipid bilayer

Bulk Transport this process requires the use of energy (active transport) this process also uses ATP vesicles are able to fuse with or form from the cell membrane

Bulk Transport can move substances up or down a concentration gradient Click here

Endocytosis vs. Exocytosis Click here

Bulk Transport Endocytosis movement of a substance into a cell by a vesicle Phagocytosis – taking in solids Pinocytosis – taking in liquids

Bulk Transport Exocytosis movement of a substance out of a cell by a vesicle