cellular communication Flashcards
communication
an act or instance of transmitting information
why did muticellular organisms take so long to evolve
difficulty in developing elaborate cell communication mechanimsa that multicellular organismas need
eukaryotic cells:plasma membrane
outer boundary. very thin layer of lipids and proteins-mechanical barrier.
maintains the diff in fluidcomposition between inside and surrounding environment of a cell
intracellullar
inside cell
extracellular
environment of a cell
plasma membrane
signal must passs through membrane to trigger cellular response. most extracellular signals cannot enter target cell.
cell commuincation aka cell signaling
principle of the plasma membrane
most abundant membrane lipids are phospholipids.
when in contact with water phospholipds molecule spontanesously organise themselves into a single sheet lipid bilayer
this lipid bilayer is not a rigid structure-pphospholipids are not held together by chemicacl bonds-they can move about within their own half of the layer
phospholipds:
membrane compnents
phospholipds are amphiphilic molecules-hydrophilic(water loving) polar end and hydrophobic (water fearing) non polar end
adaptation of membranes to temperatures
warm adapted -predominantly saturated fatty acids (straight tail)
cold adapted-high proportion of polyunsaturated fatty acids(PUFAs) (bent tail-sections of unequal length)
how many phospholid types in mammalian cells
four major phospholipids
differnt types of phospholipids
phosphatidylethanolamine
phosphatidylserine
phosphatidylcholine
sphingomyelin
asymmetry of the lipid bilayer
distribution of phospholipds between two layers of the liid bilayer can be strikingly differnt
lipid asymmetry is functionally important for cellular communication
phosphatidylinosiol is a minor phospholipid concentra6ed in the cytosolic monolayer of cell membranes plays an important role in cell signaling
membrane components
lipid molecules constitute about 50% of mass of mos animal cell membranes-nearly all of the remainder being proteines
a small animal cell contains about 10 *9 (1 billion) lipid molecules
three major classes of membrane lipids
phospholipds
chlosterol
glcolipids
lipid bilayer summary
The lipid bilayer forms the structural boundary of the cell
The lipid bilayer provides the basic structure of biological membranes
It serves as a barrier for water-soluble substances
The lipid bilayer is fluid
Cells contain up to 1000 different species of lipids
The three major classes of lipids are: phospholipids, cholesterol, glycolipids
Cholesterol contributes to the fluidity and stability of the membrane.
Inositol phospholipids residing in the cytosolic layer of the membrane play an important part in cell signaling.
types of commincation
gap junctions
signaling molecules on the surface of cells
chemical messengers
