4.1 Cell Transport Mechanisms Flashcards
Simple Diffusion Characteristics
Down a Concentration Gradient
Facilitated Diffusion Characteristics
Down a Concentration Gradient
Requires Carrier Proteins
Osmosis Characteristics
Down a Concentration Gradient
Movement of Water
Active Transport Characteristics
Against a Concentration Gradient
Requires Carrier Proteins
Requires ATP
Endocytosis + Exocytosis Characteristics
Involves Vesicle Formation
Requires ATP
Properties of a Cell Membrane
2 aqueous layers separated by a hydrophobic region
Large proteins sit across the membrane
Cholesterol
2 aqueous layers
Makes diffusion difficult for substances that aren’t lipid soluble or very small
Large Proteins
Allows larger molecules to pass through the membrane
Cholesterol
Allows fluidity of the membrane for exo + endocytosis
Properties of Simple Diffusion
Small
Non Polar
Lipid Soluble
Properties of Facilitated Diffusion
Large
Polar
Water Soluble
Osmosis Definition
The net movement of water from an area of less -ve WP to an area of more -ve WP through a partially permeable membrane
Hypertonic/ Plasmolysed
Osmotic concentration of solutes is higher than in the cell contents
Shrivelled Cells
Isotonic/ Flaccid
Osmotic concentration of solutes is equal as that in the cells
No movement of Water
Hypotonic/ Turgid
Osmotic concentration of solutes is lower than that in the cell contents
Cells swell + burst
Water Potential
Measure of the potential of water to move out of the solution
Pure Water has a WP of 0
WP= Turgor Pressure + Osmotic Potential
Turgor Pressure
The pressure generated as the swelling protoplasm pushes against the cell wall in plants
Factors affecting the rate of Active Transport
Surface Area of cell membranes
Number of carrier proteins in cell membranes
Endocytosis
Materials can be surrounded by + taken up into membrane bound vesicles
Phagocytosis
Endocytosis at a relatively large scale
Pinocytosis
Endocytosis at a microscopic scale
Exocytosis
The emptying of membrane bound vesicles at the surface of the cell
