Membrane and passive transport Flashcards
What are phospholipids?
hydrophilic head and hydrophobic tail
What is the fluid mosaic model?
-in phospholipid bilayer, proteins embed in it
-switch laterally all the time
-can move around which is important in neurotransmission
How much of the membrane is cholesterol? and what does it do?
20% stiffens the membrane using its hydrocarbon rings and decreases water solubility
Integeral membrane proteins
Type of membrane protein, Embedded permanently into the membrane, they channel or transport molecules across the membrane
what are the functions of the cell membrane
physical barrier, selective permeability, electrochemical gradients, communication, cell recognition
What are two jobs of integral proteins in the plasma membrane
peripheral protein to act as channels (transport) or carriers (bind to substance then move it through the membrane`
What do peripheral proteins do?
acts as enzymes or motor proteins involved in mechanical functions such as changing cell shape or muscle cell contraction
What is glycolax?
glycoprotein and glycolipid covering that surrounds the cell membranes that are highly specific (sugar coating)
-helps recognize other cells
cytoskeleton anchors to _____ and can interact with ____
plasma membrane and receptors
what are the function of membrane proteins
transport, enzymatic activity, signal transduction, cell-cell recognition, intercellular joining, attachment to cytoskeleton and ECM
what are tight junctions
fuse together like zipper on Ziploc bag to keep molecules from passing through and restrict membrane movement
e.g. in small intestine to stop microorganisms from entering the blood stream
What are desmosomes?
Anchoring junctions that prevent cells from being pulled apart
-bind adjacent like velcro
What are gap junctions?
Small tunnels that connect cells (connexons), facilitating the movement of small molecules and ions from cell to cell like in heart cells.
What are the two ways substances can move across the cell membrane?
passive and active process (require ATP)
what are the three types of passive transport
simple diffusion, osmosis, facilitated diffusion
What is diffusion?
The movement of particles from an area of high concentration to an area of low concentration.
what is another name for movement from high to low concentrations?
concentration gradient
what are the two criteria for how easily a substance can cross the cell membrane
1) it size and 2) lipid solubility
What is facilitated diffusion?
Movement of specific molecules across cell membranes through protein channels
What is carrier mediated transport?
when a solute binds to a carrier in the plasma membrane, which then changes shape and releases the solute to the other side
-unicellular
what is channel mediated diffusion?
Crossing through membrane protein that forms selective channel
What is osmosis?
diffusion of water across a selectively permeable membrane
what is Tonocity?
the ability of a surrounding solution to cause a cell to gain or lose water
What are isotonic solutions?
-If two solutions have the same water potential they’re said to be isotonic.
