* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download cell membrane - Fort Bend ISD
Survey
Document related concepts
Cell nucleus wikipedia , lookup
Biochemical switches in the cell cycle wikipedia , lookup
Model lipid bilayer wikipedia , lookup
Lipid bilayer wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cytoplasmic streaming wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell culture wikipedia , lookup
Signal transduction wikipedia , lookup
Cell growth wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Cytokinesis wikipedia , lookup
Cell membrane wikipedia , lookup
Transcript
Cell Boundaries TAKS Objective 2 The cell membrane All living cells have cell membranes The cell membrane (plasma membrane) regulates what enters and leaves the cell and provides protection and support (helps the cell maintain homeostasis). Cell membrane • The cell membrane is made of a double layer of phospholipids, called a lipid bilayer. • Polar heads make up the exterior of the lipid bilayer and the interior is made of it’s nonpolar tails. • It contains proteins which helps certain materials enter and exit the cell. Cell Membrane in action Click on the following link and scroll down to the The Fluid Quality of Membranes portion and show the animation (click begin) http://telstar.ote.cmu.edu/biology/downloads/ membranes/index.html Diffusion (Passive Transport) • Diffusion causes many substances to move across a cell membrane but does not require the cell to use energy. • Diffusion occurs from a higher concentration to a lower concentration until equilibrium is established. Osmosis (Passive Transport) • Osmosis is the diffusion of water through a selectively permeable membrane (selects which materials can enter or exit the cell) • Is water the solvent or solute? • http://www.tvdsb.on.ca/westmi n/science/sbi3a1/Cells/Osmosis .htm Osmosis in Action The direction of water movement across the cell membrane depends on the relative concentrations of free water molecules in the cytoplasm and in the fluid outside the cell. There are three possibilities for the direction of water movement • Hypotonic solution have less solute than water (dilute). Water will flow into a cell, causing the cell to swell. • Isotonic solutions have equal concentrations of solute and water. Water will flow in and out of the cell at an equal rate • Hypertonic solutions have more solute than water (concentrated). Water will flow out of the cell, causing the cell to shrink Facilitated Diffusion (passive transport) • In facilitated diffusion, molecules, such as glucose, that cannot diffuse across the cell membrane’s lipid bilayer on their own. They must move through the cell membrane with the help of carrier proteins. Active Transport • Active transport is a process that moves material across a cell membrane against a concentration difference (from low to high) and requires transport protein and energy (ATP). • Example: transport of K, Na, Ca ions. Active Transport • Endocytosis (moving into the cell) and • Exocytosis (moving out of the cell) are also other forms of active transport.