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Membrane structure and function - Coggle Diagram
Membrane structure and function
Membranes in selctive permeability
threecharacterisics that pass through the cell membrane
nonpolar, small, uncharged
Moves by means of “passive transport”
Cellular membrane are fluid mosaics
located within the cell membrane:
cholesterol, keeps the membrane fluid
At warm temperatures (such as 37°C), cholesterol restrains movement of phospholipids
At cool temperatures, it maintains fluidity by preventing tight packing
carbohydrates, surface markers
glycolipids
glycoproteins
Differences in membrane lipid composition
evolutionary adaptations that maintain the appropriate membrane fluidity under specific environmental conditions
The fluid mosaic model: membrane structure depicts the membrane as a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids
Phospholipids, are amphipathic, both hydrophilic and hydrophobic
Membrane proteins and their function
Transport proteins: assists hydrophilic substances across the cell membrane
Channel Proteins: tunnel like structure that moves hydrophilic molecules + ions
Aquaporins,gap junctions, plasmadesmotoa
Carrier proteins: bind two molecules and change shape to shuttle them across the cell membrane
Passive transport
NoATP required
the movement from high [] to low []
molecules are moving “down its concentration gradient”
Ex. Diffusion
the movement of particles of any substance so that they spread out evenly into the available space
Facilitateddiffusion, /w help
Ex. Osmosis
Types
hypotonic solution, swells
Hypertonic solution, shrinks
Isotonic constantly flowing in and out of mombrane
Movement of h2o molecules from high [] to low []
or
low solute to high solute
Active transport
RequiresATP
Movement of molecules from a low [] to a high []
”molecules are moving against the [] gradient
Ex.Sodium Potassium pump (animals)
proton pump (plants, bacteria, and fungi)
Membrane potential: the voltage across a membrane created by the differences in the distribution of pos + and neg+ ions across the membranes
Electrochemicalgradient, drive diffusion of ions across membrane
A chemical force (ion [] gradient)
an electrical force (effect on membranes potential on ion’s movement)
Cotransport,when active transport of a solute indirectly drives transport of other substances
Bulk transport
exocytosis: going out
-Small molecules and water enter or leave the cell through the lipid bilayer or via transport proteins
-Large molecules, such as polysaccharides and proteins, cross the membrane in bulk inside vesicles
Endocytosis:going in
Phagocytosis: cell eating
Pinocytosis: cell drinking
Receptor-mediated endocytosis
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