Lecture 6- extracellular structures

Question 1

coordination and communication b/w cells in tissues is accomplished by the:

Answer 1

extracellular matrix (ECM)

Question 2

plant cell wall

• function:
• structure:
• other plant-specific structures

Answer 2

fxn= maintains cell shape & prevents excess uptake of water
structure= cellulose main ingredient 

• lignin is another structure- forms structure of wood

Question 3

define the ECM

Answer 3

all the structures/ fibers happening outside of the cell

Question 4

function of the animal ECM

Answer 4

• maintains cell attachments across long distances
• allows communication
• maintains tissue integrity
• stores growth factors

Question 5

structure of animal ECM

Answer 5

secreted glycoproteins (proteins covalently linked to sugars). made in the golgi

Question 6

3 main components of animal ECM

Answer 6

• Integrins: integral membrane proteins that link ECM to cytoskeleton
• Collagen: forms structure of ECM; connects cells over long distances
• Fibronectin: links collagen fibers to integrins (adaptor in between)

Question 7

Epithelial cells are particularly vulnerable to ____. Why?

Answer 7

cancer

- b/c they’re exposed to carcinogens in enviro

Question 8

one major step in cancer progression is ___ ___ ____. Why?

Answer 8

detachment from ECM

- because potential tumor must find room to grow

Question 9

Animal cell-cell attachments 
attachments happen over long distances like the ECM but cells can also be directly attached to one another by 3 different attachment types:
1.
2.
3

Answer 9

1. Tight junctions
2. desmosomes
3. gap junctions

Question 10

what’s the purpose of a set of intercellular junctions in epithelial layers?

Answer 10

maintain tissue integrity

Question 11

function of tight junctions in animal cell-cell attachments

Answer 11

• fxn as rivets to seal cells together

- prevents passage of molecules (eg pathogens) b/w cells and enviro (and vise versa)

Question 12

fxn of desmosomes in animal cell-cell attachments

Answer 12

• distribute stretching forces across a tissue

- connect adjacent cytoskeletons via intermediate filaments

Question 13

disease involving intermediate filaments

Answer 13

blisters every time you bend

no desmosomes distributing the force

Question 14

fxn of gap junctions in animal cell-cell attachments

Answer 14

• provides non-selected transport of small molecules b/w adjacent cells
• allows coordination of muscle contraction in cardiac muscle : Ca can spread b/w cells; Ca is the contractile signal

Question 15

what are gap junctions in animal cell-cell attachments

Answer 15

gap junctions= large channels that allow sharing of nutrients and signals