Exam 4 (6)

Question 1

Gap Junctions: Define + What do?

Answer 1

Transmembrane intercellular channel of connexins; allows passage of small molecules –> could be a site of transferring membrane potential

Question 2

ECM Purpose

Answer 2

Holds tissues together and activates intracellular signaling pathways (ex. growth, proliferation, gene expression)

Question 3

ECM Structure

Answer 3

Proteins of ECM comprise Basal Lamina (btwn layer) and Connective Tissue

Components include
i) Proteoglycans (glycoproteins that are cell cushions)
ii) Collagens (structural integrity/mechanical strength)
iii) Multiadhesive Matrix Proteins (crosslinking adhesion receptors and ECM components) [ex. fibronectin + laminin]

Question 4

Basal Lamina Definition/Purpose

Answer 4

Thin sheet-like meshwork of ECM that surrounds/underlies tissues where
i) Cells can rest, organize, and compartmentalize
ii) Tissues can be prepared
iii) Developing cells can be guided

Question 5

Four Components of the Basal Lamina

Answer 5

1. Type IV Collagen
2. Laminins
   (1 and 2 form a Fibrous 2D Network)
3. Perlecan
4. Nidogen
   (3 and 4 crosslink the two Fibrous 2D Networks formed above)

Question 6

How is Basal Lamina connected?

Answer 6

Linked to cells with adhesion receptors and connective tissue by a layer of collagen in a proteoglycan-rich matrix

Question 7

Connective Tissue Structure

Answer 7

Made of ECM materials, most importantly fibroblasts (cell that secretes ECM proteins) and fibrillar collagen (Collagen I)

Question 8

Structure of Collagen

Answer 8

3 collagen peptides bundled into a triple helix (called pro-collagen); each pro-collagen assembles further into fibers