Both in animal and plant cell Selective permeable Composed of : Proteins Glycoprotein Glycolipids Phospholipid Cholesterol and lipoprotein (a few)
Fluid mosaic model Lipid bilayer Phospholipid Hydrophilic head (polar) Hydrophobic tail (non-polar) Embedded protein Embedded between layer Integral protein Peripheral protein (not embedded) Free movement within layer As carrier and channel protein Cholesterol Make phospholipid stay in position ‘Fluid’ protein and lipid molecules able to shift and move laterally ‘Mosaic’ the protein molecules form mosaic-like patterns when viewed fromthe top.
Functions of cell membrane Barrier Maintain internal environment of cell Communication between cell Markers to foreign materials Transportation(Text book page 29)
In animal cells, continuous with nuclearmembrane Extends throughout cytoplasm Two regions - rough and smoothRough ER Smooth ER
FunctionsROUGH ER SMOOTH ERProminent in cells that manufactureprotein for export ; digestiveenzymes, hormones, structuralprotein or antibodiesNecessary for steroid synthesis,metabolism and detoxification ofsubstances in liver, phospholipidsynthesis and excitation-contraction coupling in skeletalmuscleWith ribosome Without ribosome
MOVEMENT OFMOLECULES/SUBSTANCESIN AND OUT OF THE CELL
The movement of molecules are based onconcentration gradient Concentration gradient ; Means the number of molecules or ions in oneregion is different than the number in anotherregion In the absence of other forces, a substancemoves from a region where it is moreconcentrated to one where it‟s lessconcentrated - “down” gradient
Phagocytosis; “cellular eating”. In phagocytosis, the cell engulfs a particle byextending pseudopodia around it andpackaging it in a large vacuole. The contents of the vacuole are digestedwhen the vacuole fuses with a lysosome.
In pinocytosis; “cellular drinking” a cell creates a vesicle around a droplet ofextracellular fluid.
EXOCYTOSIS Transport of molecules Out of a cell Enclosed in vesicle Move to cell surface membrane Fuse release
Both diffusion and facilitated diffusion are forms of passive transport of moleculesdown their concentration gradient, while active transport requires an investment ofenergy to move molecules against their concentration gradient.