ـLong, unbranched polysaccharide chains (70-200 sugar residues ) composed of repeating disaccharide sugar units। The repeating disaccharides are linked by 1,4 linkages in βconfiguration.

Highly negatively charged due to sulfate and carboxyl groups.Which attract Na+ions and water.

One of two sugar residues in repeating disaccharide is always an amino sugar and may contain uronic acid
–
N-acetylglucosamine
–
N-acetylgalactosamine

ـmain groups of GAGs, distinguished by sugar residues, type of linkage between residues and number and location of sulfate groups
–
Hyaluronicacid
–
Chondroitin4 sulfate and chondroitin6 sulfate
–
Dermatansulfate
–
Heparansulfate and heparin
–
Keratansulfate I, II

Antibody-dependent cell-mediated cytotoxicity (ADCC) is shown on the left। Antibody opsonization and activation of the complement leads to antibody-dependent, complement-mediated virolysis, phagocytosis directed against free virions or infected cells (only the free virus is shown) are shown on the right। NK, natural killer।

1.Supporting and retaining the cytoplasm (inner cell) and help shape of many organelles within the cell, e.g., mitochondria, ER, Golgi complexes, secretary granules, lysosomes and nuclear membranes.

2. They have selective permeability for:
nutrients inand waste products out.
non-polar molecules and some small polar molecules can cross.
Most polar compounds, e.g. amino acids, must be specifically transported across the membrane by proteins (Transport).

3. Plasma membranes plays roles in cell-cell interactions and transmembrane signaling (e.g. starvation, rise of glucose level).

4-They provide e sites of energies transduction such as photosynthesis and Phosphorylationoxidation