Extracellular Matrix

Question 1

Bacterial cell walls

Answer 1

-shape (rod vs spiral)
-protect from osmotic pressure
- made of peptidoglycan

Question 2

Penicilin and bacteria

Answer 2

Penicillin kills bacteria by inhibiting enzyme responsible for making the cross-links

Question 3

Eukaryotic Cell Walls- (plants)

Answer 3

-made of cellulose (Beta gluc monomers)
- after leaving cell= associate into myofibrils

Question 4

Euk cell wall (fungi)

Answer 4

• made of chitin
  –>made from a glucose derivative

Question 5

Myofibrils and Pectin

Answer 5

• Myofib interact w/ other sugars and proteins to make the cell wall

-pectin has many neg charged residues, which can trap cations and water molecules creating a gel

Question 6

ECM

Answer 6

fills space bt cells and binds cells and tissues together

Question 7

types of ECM

Answer 7

• made from secreted proteins and polysaccharides

1. basal lamina
2. collagen
3. elastin

Question 8

Basal Lamina

Answer 8

layer of ECM sec by epithelium cells (also surround muscle cells, fat cells, and peripheral nerves)

• abundant in connective tissues

Question 9

main family of proteins in ECM (Collagens)

Answer 9

• form a triple heliz structure from amino acids secreted from the cell
• further associate to form collagen fibers

Question 10

Elastin

Answer 10

-important component of ECM (esp connective tissue)
- cross-linked to allow them to stretch and retract
- work in conjunc w/ collagen to give elasticity to the skin

Question 11

Glycosaminoglycans

Answer 11

(GAGs)
- make a polysaccharide gel that protein fibers are embedded into

• link proteins to for proteoglycans

Question 12

Adhesion proteins

Answer 12

link the components of the matrix together (ex: collagen and proteoglycans) AND links cell to the matric

ex: fibronectin and laminin

Question 13

ECM and cell attatchment

Answer 13

• made via integral proteins ex: integrins
  -will recognize and bind to specific amino acid sequences found in diff components of the matrix or cytoskeleton

Question 14

integral proteins

Answer 14

present in focal adhesions and hemidesmosomes

Question 15

Locomotion steps

Answer 15

1. protrusion
2. Substrate adhesion
3. Traction/cell body movement

Question 16

protrusion

Answer 16

The leading edge usually shows filopodia and lamellipodia. These extensions probe forward in search of a new substratum contact site.

Question 17

substrate adhesion

Answer 17

If and when the leading edge encounters an adhesive region of the substratum it will attach, stabilizing the forward extension. The mechanism of attachment involves integral membrane receptors and their coupling to internal cytoskeletal elements.

Question 18

traction/ cell body movement

Answer 18

Once a new forward contact has been made a mechanism must exist to move the bulk of the cell cytoplasm in that direction. Several activities are believed to contribute.

Question 19

Selectins

Answer 19

ligands recognized- carbs
stable cell junction- no

Question 20

integrins

Answer 20

ligand recog- ECM
stable junctions?- focal adhesions and hemidesmosomes

Question 21

lg superfamily

Answer 21

lig recog: integrijns
stable cell junc? - not usually

Question 22

cadherins

Answer 22

-other cadherins recog
-cell junc stable? adherens junctions and desmosomes

Question 23

Loss of Cadherins…

Answer 23

in epithelial cells can lead to cancer bc of no contact inhibition and makes cancer cells migration and proliferation easier

Question 24

Adhesion junctions

Answer 24

multi portein complexes that connect cells together at cell-to-cell and cell-to-matric junctions

Question 25

Tight Junctions

Answer 25

• form seals that prevent molecules from passing in between epithelial cells
  -separate the cell mem into basal and apical domains
• not good at holding cells together

Question 26

junctional complex

Answer 26

adhesion junctions, tight juntions and desmosomes to form a junctional complex

Question 27

Gap junctions

Answer 27

Channels bt two cells
-exchange diff molecules
-made by joining two connexons
–> connexons made by 6 su

Question 28

plasmodesmata

Answer 28

adhesion bt plant cells is mediated by cell wall components (instead of mem proteins)

plas mem of adjacent cells are continuous

imp in plant cell signaling