Lecture 6

Question 1

Apical Surface Modifications: Microvilli

1. AKA
2. General structure
3. Function
4. Found

Answer 1

1. Brush borders!
2. Fingerlike projection of the apical cell membrane. Supported by cross-linked actin bundles. Relatively stiff. Form a uniform brush border across the apical emmbrane
3. Increase surface area of absorption
4. Found on the intestinal epithelium and parts of the renal tubules (makes sense)

Question 2

Apical Surface Modifications: Microvilli

1. Core consists of
2. Core extends into
3. Core binds to
4. Distal end of core is capped by? Function?
5. Cross linked by

Answer 2

1. Actin filaments
2. terminal web (network of cytoskeletal proteins under the apical membrane of the cell)
3. Intermediate filaments in the web
4. formin. Regulates assembly of the actin filaments
5. Villin and Fimbrin

Question 3

Apical Surface Modifications: Cilia

1. Structure
2. Structure of doublets

Answer 3

1. 9 peripheral doubltes + central pair of microtubules.
2. Alpha tubule: 13 protofilaments. Pairs of dynein arms project to the beta unit of the next toublet

Betal tubule: 10-11 protofilaments. It is incomplete. One of it’s walls IS the alpha tubule