Lecture 5 Cell Junctions

Question 1

Microvilli

Answer 1

apical domain membrane structure, organised on actin filaments

Immobile

In enterocyte microvilli form a striated border and are relatively short around 1 nanometer

In nephrocyte/kidney tubule cells they form a bush border and are longer ranging from 2-6 nm

Question 2

Microvilli where are they found / what is their role

Answer 2

Microvilli are found in various cell types and serve to increase the absorptive surface area of the cell

Question 3

Sterocilia

Answer 3

Apical domain membrane structure, organised on actin filaments

Longer than microvilli ( 5-7 nm)

Immobile

Question 4

Sterocilia localisation

Answer 4

Inner ear (function in sensory perception)
Epididymis

Question 5

CILIA

Answer 5

apical domain membrane structure, organized on microtubules

Question 6

Cilia localisation

Answer 6

Respiratory epithelium
Fallopian Tube

Question 7

Cellular junctions

Answer 7

• latero-basal domain membrane structure
• role in cell adhesion
• can only be seen with the help of TEM

Question 8

Specialised cell junctions

Answer 8

• tight (occluding)
• anchoring (adherent)
• communicating (gap)

Question 9

Tight junction
Roles

Answer 9

Appear as closing the intracellular space when viewed through EM

Barrier
Contributes to the maintenance of cell polarity

Question 10

Desmosons types

Answer 10

Belt
Spot

Question 11

Hemidesmosomes

Answer 11

Same appearance as desmoseoms but the location is different

Question 12

Gap junctions

Answer 12

2 adjoining membranes are crossed by hydrophile channels = connexons

Question 13

Gap junctions
What can pass
What cannot pass

Answer 13

What can
An organic ions
Small water soluble molecules

What can’t
Proteins
Nucleic Acids