Lecture 8 Flashcards
Cell walls
extracellular structures that distinguish plant cells from animal cells
they protect, maintain shape and prevent excessive uptake of water
Gram positive bacteria
- simpler structure
- single layer
Prokaryotes
two types of cell wall, identified by different staining properties
Gram negative bacteria
more complex structure, two layers, thin peptoglycan and exterior lipsaccharide
Fungi
some are single cells like yeast
many fungi have hyphae
Fungal cell walls
made of chitin
chitin is acetyl glucosamine
Plant cell walls
cell wall called a frustule
made of silica
potential use for bio production
Extracellular matrix
holding animal cells together
ECM consists of
glycoproteins such as:
-collagen
-proteoglycans
-fibronectin
Integrins
ECM proteins bind to receptor proteins in the plasma membrane
- the skin ECM is primarily composed of collagen and proteases
- deterioration of eCM= loss in collagen production = wrinkles
- vitamin C increases collagen production
- UV damage kills fibroblasts cells
Communication intercellular junctions
plasmodesmata (plants)
gap junctions (animals)
Adhesion intercellular junctions
tight junctions (animals)
desmosomes (animals)
Cellular connections
gap junctions
tight junctions
desmosomes
Gap junctions
provide cytoplasmic channel between adjacent cells
Tight junctions
membranes of neighbouring cells are pressed together, preventing leakage of extracellular fluid
Desmosomes
anchoring junctions
fasten cells together into strong sheets
