Exam 3 Theisen review PART 2

Question 1

Effects of Rho GTPases on Actin Organization:

Rho

Answer 1

Rho activation promotes both the bundling of actin filaments with myosin II filaments into stress fibers and the clustering of integrins and associated proteins to form focal contacts (FEET).

Question 2

Effects of Rho GTPases on Actin Organization:

Cdc42

Answer 2

activation triggers actin polymerization and bundling to form filopodia.

Question 3

Effects of Rho GTPases on Actin Organization:

Rac

Answer 3

activation promotes actin polyerization at the cell periphery leading to the formation of Lamellipodia extensions.

Question 4

Rac/Cdc42 =

Rho =

Answer 4

Rac/Cdc42= dynamic actin
Rho= rigid actin.

Question 5

Two main ways to connect animal cells and provide the strength:

Answer 5

-Connective tissue: such as bone or tendon, ECM is plentiful and cells are sparsely distributed within it.

Epithelial Tissue: The cytoskeleton of cells is linked from cell to cell by anchoring junctions and the ECM is scanty, consisting mainly of a thin mat called the BASAL LAMINA.

-CELL-matrix attachments bond epithelial tissue to the connective tissue beneath it.

Question 6

Transmembrane adhesion proteins

Answer 6

• play a central role in anchoring junctions.
• spand the membrane with one end linking to cytoskeleton inside the cell and the other end linking to other structures outside the cell.
• Two families-based on external attachments
• —cadherin and Integrin

—Two other superfamilies fo cell-cell adhesion molecules are selecting and immunoglobulin (Ig) superfamily.

Question 7

Transmembrane protein that mediates cell-cell connection

Answer 7

Cadherin

Question 8

Transmembrane protein that mediates attachment of cells to matrix?

Answer 8

Integrin

Question 9

Adherens Junctions

Answer 9

• are an essential part of the machinery for modeling the shape of multicellular structures
• primarily present in epithelia.
• often for a continuous adhesion belt (zonula adherens) close to apical face, encircling each of the interacting cells in the sheet.
• within each cell, a contractile bundle of acting filaments lies adjacent to the adhesion belt, oriented parallel to the plasma membrane and tethered to it by the cadherins and their associated intracellular anchor proteins.

Question 10

The intermediate filament networks of adjacent cells are indirectly connected to one another through _____ and to the basal lamina through __________?

Answer 10

desmosomes, hemidesmosome

Question 11

The particular type of intermediate filaments attached to the desmosomes depends on the cell type. What is in most epithelial cells?

Answer 11

keratin filaments.

Question 12

Right junctions consist of a branching network of _______ ________ that completely encircles the apical end of each cell in the epithelial sheet.

Answer 12

Sealing Strands

Question 13

The tight junctions is seen as a series of ______ ______ between the two interacting plasma membranes, each connection corresponding to a sealing strand.

Answer 13

Focal connections

Question 14

What are the two main tight junction proteins?

Answer 14

Claudin (main) and occluding

Question 15

How is the sealing strand of a tight junction composed?

Answer 15

a long row of 4 pass transmembrane adhesion proteins embedded in each of the two interacting plasma membranes.

Question 16

To fully polarize, the epithelial cell must then separate the apical from basolateral surfaces via?

Answer 16

Right junction formation

Question 17

What three conserved polarity protein complexes control polarization process and maintain polarity?

Answer 17

Par, Crumbs and Scribble.

Question 18

Gap junctions are made up of 4 pass transmembrane proteins called

Answer 18

connexons (hexameric channels contain 6 protein subunits)

Question 19

What proteins are contained in the basal lamina?

Answer 19

laminin and type IV collagen

Question 20

An integrin molecule consists of two noncovalently associated subunits ___ and ____

Answer 20

alpha and beta

Question 21

Both subunits of integrin span the cell membrane with _________ and _______

Answer 21

short c-terminal tails and Large N-terminal extra cellular domains.

Question 22

Integrin: The intracellular tail of ___________ binds to a complex of proteins that form a linkage to cytoskeleton

Answer 22

Beta subunit

Question 23

integrin: Intracellular linkage to actin is mediate by _______ and a set of other anchorage proteins

Answer 23

talin

Question 24

Integrins signal bidirectionally: Information flow from extracellular stimuli to induce intracellular changes ( ), but intracellular stimuli can also cause extracellular changes ( ).

Answer 24

outside-in signaling…………. Inside-out signaling.

Question 25

Focal contacts

Answer 25

sites where ECM, Integrins & cell cytoskeleton interact.

Question 26

FAK:

Answer 26

Cytoplasmic Protein Tyrosine Kinase

• Recruited by talin or paxillin
• clustered FAK autophosphorylate providing docking site for Src-family kinases, leading to src activation.

**FAK and Src-family kinases cause outside in signaling.

Question 27

Collagen

Answer 27

-Repeating triplet sequence
Gly-X-Y-Gly-X-Y-Gly-X-Y

• Triple Helix:
• -each chain is twisted to the left
• • the chains helically twist around each other to the right.

Question 28

Co-factors of prolyl/lysyl hydroxylaes

_Lysyl/prolyl hydroxylases add –OH groups for collagen assembly

Answer 28

ascorbate, Fe2+

Question 29

After being secreted into the ECM, collagen molecules assemble into higher order polymers called

Answer 29

collagen fibrils.