Cell Communication and Adhesion

Question 1

What is the difference between the ECM of connective and epithelial tissue?

Answer 1

Connective Tissue - Plentiful ECM, sparsely populated with cells, matrix rich in fibres inc. collagen
Epithelial Tissue - Sheets of tightly bound cells, cellular cytoplasm bears weight

Question 2

What is cellular polarity?

Answer 2

Apical and basolateral cell surfaces have different characteristics

Question 3

What type of cell junctions maintain the selective barrier function of epithelial cells?

Answer 3

Occluding/tight junctions

Question 4

What are the two types of anchoring junctions, to what do they connect?

Answer 4

Adherens Junctions - Actin filaments

Desmosomes - Intermediate filaments

Question 5

What are the three functional types of cell junctions?

Answer 5

Occluding/tight junctions, anchoring junctions, communicating junctions

Question 6

What type of junction allows the passage of ions between cells?

Answer 6

Communication junctions - Gap junctions

Question 7

What controls the permeability of gap junctions?

Answer 7

pH, calcium ion concentration and hormones

Question 8

Which cells secrete the macromolecules of the ECM?

Answer 8

Fibroblasts

Question 9

Which molecules link to form proteoglycans?

Answer 9

Proteins and glycosaminoglycans (GAGs)

Question 10

Which of these are classes of macromolecules?
A. GAGs
B. Enzymes
C. Fibrous Proteins
D. Protein kinases

Answer 10

A and C

Question 11

Which type of GAG is not linked to a protein, and what does it do?

Answer 11

Hyaluronic Acid - wound repair and joint lubrication

Question 12

What are Connexons?

Answer 12

Channel proteins involved in gap junctions

Question 13

Which of these is a GAG?
A. Keratin
B. Keratan

Answer 13

B

Question 14

What are Heparan sulphate and Chondroitin sulphate?

Answer 14

Groups of GAGs

Question 15

What is the function of heparin?

Answer 15

Anticoagulant

Question 16

What is the structure of GAGs?
A) Fluid mosaic
B) Gel-like ground substance
C) Globular
D) Long strands

Answer 16

B

Question 17

What does fibronectin do?

Answer 17

Promotes attachment of fibroblasts and related cells to the ECM

Question 18

What does laminin do? Specifically, which type of collagen does it bind to?

Answer 18

Promotes attachment of epithelial cells to basal lamina

Type IV

Question 19

Where are the four most common types of collagen found?

Answer 19

Type I - bone, skin, dentin, cornea, tendon, blood vessels, fibrocartilage
Type II - Cartilage
Type III - Skin, ligaments, organs, blood vessels
Type IV - Basement membrane

Question 20

What could a bioengineer use as a substrate for cell culture?

Answer 20

GAGs

Question 21

Which of these does fibronectin bind to?

Collagen, antibodies, fibrin, heparin, haemoglobin, laminin, osteoblasts, specific cell receptors

Answer 21

Collagen, fibrin, heparin, specific cell receptors

Question 22

What part of fibronectin do integrins recognise?

Answer 22

The RGD complex

Question 23

Laminin receptors recognise RGD sequence on laminin.

True or False?

Answer 23

False

Question 24

Which intracellular molecule binds to fibronectin receptors? What happens when they bind?

Answer 24

Protein kinases bind and phosphorylate tyrosine residules in order to interact with actin.

Question 25

How can tumour cells decrease integrin affinity?

Answer 25

They increase the phosphorylation of tyrosine residues