Week 11 - ECM Organization

Question 1

In the ECM, what does Collagen provide?

Answer 1

Provides tensile strength; resists pulling forces.

Question 2

What do fibriallar collagens form?

Answer 2

Form rigid cables; gnerally composed of 3 chains wound in a triple helix.

Question 3

In the ECM what is collagen secreted by?

Answer 3

Secreted by fibroblasts; epithelial and smooth muscle cells.

Question 4

What is a glycoprotein?

Answer 4

A protein with any kind of sugar on it.

Question 5

What are Proteoglycans?

Answer 5

Proteins modified with glycosaminoglycans (GAG).

Question 6

What is a GAG?

Answer 6

glycosaminoglycans; long linear chains of a repeating disaccharide (2 repeating sugars); highly negatively charged.

Question 7

Proteoglycans have at least one side chain of what?

Answer 7

One sugar side chain that MUST be a GAG.

Question 8

All proteoglycans are glycoproteins, but not what?

Answer 8

NOT vice versa.

Question 9

What are the 2 kinds of glycoproteins?

Answer 9

1. Proteoglycans in the ECM

2. Secreted glycoproteins

Question 10

Proteoglycans fill what?

Answer 10

They are space filling.

Question 11

What is Hyaluronan?

Answer 11

A simple GAG; long cain of repeating disaccharide subunits.

Question 12

Hyaluronan is sometimes just a GAG, but also sometimes what?

Answer 12

Also sometimes linked and PART of a proteoglycan.

Question 13

Most GAG’s are synthesized where?

Answer 13

Synthesized inside the cell on proteins, and exocytosed.

Question 14

Hyaluronan is spun directly from where?

Answer 14

Directly from the cell surface by a membrane complex protein.

Question 15

What does Elastin give tissues?

Answer 15

Gives tissues elasticity.

Question 16

Networks of elastin stretch and relax like what?

Answer 16

Like a rubber band.

Question 17

What does Fibronectin do in the ECM?

Answer 17

It binds collagen and cell surface receptors?

Question 18

What is the structure of a Fibronectin?

Answer 18

• a dimer linked by disulfide bonds

- The RDG site is the cell binding site.

Question 19

Each fibronectin is composed of different what?

Answer 19

Several different linked domains; each having a different function.

Question 20

The basal lamina underlies all what?

Answer 20

Underlies all epithelia.

Question 21

Basal lamina influences cell what?

Answer 21

Influences cell polarity.

Question 22

Epithelial cells do what to the basal lamina?

Answer 22

They secrete what influences the basal lamina.

Question 23

What 3 things do Basal lamina surround?

Answer 23

1. Muscle
2. Fat cells
3. Schwann cells

Question 24

In the kidney, the basal laminal does what?

Answer 24

It divides two cell sheets; acts as a selective filter.

Question 25

The basement membrane/basal lamina prevents what?

Answer 25

Prevents fibroblasts in the underlying connective tissue from interacting with epithelial cells.

Question 26

The basement membrane allows for the passage of what?

Answer 26

Allows the passage of macrophages and lympocytes.

Question 27

How does Laminin organize the basement membrane?

Answer 27

Organizes by interacting with other components of the ECM and integrin in the plasma membrane

Question 28

What 2 components of the ECM are involved in cell migration?

Answer 28

1. Fibronectin

2. Laminin

Question 29

Laminin is a Trimer of what?

Answer 29

1. a-laminin (alpha)
2. B-laminin (beta)
3. y-laminin (gamma)

Question 30

Laminin is shaped like what letter?

Answer 30

Like a T.

Question 31

What do hemidesmosomes do for the epithelial cells and basal lamina?

Answer 31

They spot-weld epithelial cells to the basal lamina; also spot-weld other cells to their ECM.

Question 32

Keratin filaments are linked to what inside the cell?

Answer 32

They are intermediate filaments inside the cell that are linked to laminin in the ECM.

Question 33

How are Keratin filaments linked to laminin in the ECM?

Answer 33

Linked through interaction with the transmembrane protein integrin.

Question 34

Integrins interact with laminin to organize what?

Answer 34

To organize the basement membrane.