CELL TRANSPORT Courtesy of:

Fluid Mosaic Model Courtesy of:

Fluid Mosaic Model Hydrophilic Heads Hydrophobic tails Courtesy of:

Polarity Hydrophilic (water loving/ attracted to) - phosphate heads Hydrophobic (water fearing/ Repelling) –lipid tails Effects of polarity on permeability Courtesy of:

Polarity Courtesy of:

Types of Transport Courtesy of:

Passive Transport No energy (ATP) needed High to low concentration simple diffusion facilitated diffusion osmosis Courtesy of:

Simple diffusion Process by which molecules of a substance move from areas of higher concentration to areas of lower concentration. Courtesy of:

Diffusion first a concentration gradient is necessary, diffusion occurs moving from higher to lower concentration results in dynamic equilibrium, then equal particles keep moving in each direction, no further change in concentration

Osmosis The diffusion of water through a selectively permeable membrane Courtesy of:

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Solutions Hypotonic: below strength –solutions having lower concentrations of solutes outside the cell Example: 15% salt outside of the cell and 20% inside. Which way will the water diffuse? –water leaves solution and goes into cell Hypertonic: above strength –solutions having higher concentrations of solutes outside the cell Example: 70% H 2 O inside the cell and 40% salt outside of the cell. –water leaves cells and goes into solution Isotonic: equal strength –Solutions having equal concentrations of solutes inside and outside the cell –the same amount of water leaves the cell as the water that enters the cell

Animal Cells (red blood cells) Courtesy of:

Osmotic Pressure pressure exerted on hypertonic side of a semipermeable membrane necessary to achieve equilibrium

Plant Cells Courtesy of:

Turgor Pressure main pressure of cell contents against the cell wall determined by water content of the vacuole, resulting from osmotic pressure

More on Plant Cell Osmosis Turgid: –when in dilute solutions, –plant cell is swollen and hard –pressure is so high, no more water can enter –pressure works against osmosis –makes plants stand up Flaccid –when in concentrated solutions –plant wilts Plasmolyzed: –plasma membrane pulls away from cell wall due to loss of water –cell wall eventually collapses if not placed in a hypotonic solution

Facilitated Diffusion Carrier molecules (protein channels) assist in moving large particles from a high concentration to a low concentration These particles fit through the membrane but are assisted Courtesy of:

Facilitated Diffusion Courtesy of:

Active Transport energy needed moving from low to high concentration moving against the concentration gradient Courtesy of:

Active Transport Courtesy of:

Endocytosis process of taking material into the cell by means of infoldings of the cell membrane these “pockets” break loose from the outer portion of the cell membrane and forms a vacuole (inside cytoplasm) phagocytosis and pinocytosis

Endocytosis Courtesy of:

Phagoyctosis cell eating extensions of cytoplasm surround a particle and package it within a food vacuole the cell engulfs it considered active transport requires energy

Phagocytosis Courtesy of:

Pinocytosis cell drinking cells take up liquid from the surrounding environment small pockets form along cell membrane pockets fill with liquid pockets pinch off to form vacuoles inside the cell

Pinocytosis Courtesy of:

Exocytosis cells release large amounts of material from the cell membrane of the vacuole surrounding material to be released fuses with cell membrane forces material out of the cell

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