Cell Biology Test 3

Front 1

Myosin 2

Back 1

a globular head, 2 heavy chains for head and ATP binding, 2 regulatory light chains for contraction, and 2 essential light chains for structure

Front 2

Actin drugs

Back 2

Phalloidin: binds and stabilizes filament, ruining cellular functioning; use to stabilize and visualize actin in cell.

Lantrunculin A: caps plus end of F-actin, inhibiting polymerization.

Cytochalasin B: binds actin monomers and prevents polymerization.

Front 3

Microtubule drugs

Back 3

Taxol: found in Pacific Yew but can be synthesized. Binds to B-tubulin, resulting in stabilization and hyperproliferation which cannot be stopped, thus inhibiting cell rep.
Colchicine, Vinblastine, vincristine: bind to tubulin heterodimers, preventing polymerization

Front 4

Subunit binding proteins in actin/microtubules

Back 4

profilin, thymosin, and Stathmin: binds to tubulin subunits, sequestering so the rate of polymerization of microtubules is slowed and GTP is hydrolyzed to GDP resulting in catastrophe and loss of stability.

Front 5

Severing Proteins

Back 5

Gelsolin and Katanin (doesn't cap)

Front 6

Centrioles

Back 6

Centrosomes, or microtubule organizing centers, have two orthogonal centrioles which consist of 9 triplet microtubules surrounded by a pericentriolar matrix and gamma- tubulin ring complexes which create microtubules.

Front 7

End Binding Proteins

Back 7

EB1 and XMAP215 bind to the end of microtubules and stabilize them, allowing for elongation.

Front 8

Dynactin Complex

Back 8

Tethers microtubule motor proteins to vessicles. Dynein binds to ARP-1 which is associated with Spectrin. Spectrin is bound to ankyrins, which can associate with glycoproteins on vessicles.

Front 9

Cilia and Flagella

Back 9

Many hundred cilia are found on a cell while only a few flagella can be found. Both have axonemes, which have2 lone microtubules surrounded by 9 paired microtubules (central singlets). Radial spoked keep the outer doublets where they need to be. Nexin keeps the doublets the right distance from eachother. Cilia function by a power and then recovery stroke and flagella move in a sinusoidal pattern. A bassal body of 9 triplet microtubules anchor the axoneme.

Front 10

Hemidesmosomes and collagen

Back 10

Intermediate filaments associated with alpha-actinin bundled actin is associated with vinculin, associated with talin associated with the talin binding site of integrin. Integrin is then bound complementarily to a RGD sequence of fibronectin to its cell attachment site, which is then bound to collagen.

Front 11

Neurolation

Back 11

A sheet of epithelial cells is associate by epithelial (E) and neural (N) cadherins. N-cadherin bound region begins invagination and is pinched off to create a neural tube.

Front 12

Cadherin

Back 12

Cadherin is a cell adhesion molecule (CAM) found in adherens and desmosomal junctions. The molecules have 5 calcium binding sites which need to be bound in order for rigid structure for adhesion between cells. Cadherin binding is homotypic, and thus cells will organize to be associated with other cells with the same cadherin molecules (cell type). Catenin molecules assist in the association of actin or intermediate filament with the cadherin molecule in the cytosol.

Front 13

ERM

Back 13

Ezrin, Radixin, and Moesin. Activated by signal mediated PIP2 and anchors actin to integral membrane proteins.

Front 14

Sarcomere

Back 14

Tropomodulin: minus end capping of actin.
Z-cap: Plus end capping.

Titin: Anchors myosin
Nebulin: Structure and regulation of actin.
Troponin: TIC requires calcium to change tropomyosin so that myosin may bind to actin filaments.

Front 15

Who theorized the dynactin complex?

Back 15

Mitchinson and Kirshner

Front 16

Who did the speckled microscopy

Back 16

Clare Waterman

Front 17

Gap Junctions/ Plasmodesmata

Back 17

Gap junctions are made by the interaction of two separate six-membered connexon polymers. Homomeric/heteromeric and homotypic/heterotypic.
Plasmodesmata have desmotubules

Front 18

Laminin

Back 18

A crucial component of the ECM, laminin proteins associate with itself and other proteins. An alpha domain is for association with integrins. Beta and gamma domains are for self assembly. Across a coiled coil domain, the laminin may associate with many other ECM molecules.

Front 19

Aggregan

Back 19

Space filling, dense, and very large. Hyaluronan backbone is bound my proteins to link to side protein chains bound to saccarides.

Front 20

Collagen

Back 20

Three collagen peptides form a triple stranded molecule, which is exported from the cell and the terminal ends are cleaved, allowing self-assembly into collagen fibrils and fibers. Glycine on every third AA and hydroxylysine/ hydroxyproline also very abundant, synthesized from ascorbic acid, which a deficiency of results scurvy

Front 21

GAGs

Back 21

Glycosaminoglycans are long polysaccharides of repeating dissacarides. Can be connected to the serine of peptides to create proteoglycans. An example is hyaluronan, which is very negatively charged, pulling in ions and consequently water into the cell, creating a gel.