Cell Structure 3

Question 0

What structures are associated with desmosomes and help anchor the nucleus?

Answer 0

Intermediate filaments.

Question 1

T or F. Many integral membrane proteins are anchored by the actin cortex.

Answer 1

True.

Question 2

Microfilaments are composed of ______.

Answer 2

Actin.

Question 3

What supports the cell membrane and anchors integral proteins?

Answer 3

Actin cortex.

Question 4

Cytoplasmic streaming, cell motility, muscle contraction, and cell division all have what in common?

Answer 4

Microfilament involvement.

Question 5

The movement of actin filaments by addition and loss of actin on the + and - end is a process called _________.

Answer 5

Treadmilling.

Question 6

Which actin binding proteins are involved in bundling?

Answer 6

Fascin, fibrin. Important for microvilli.

Question 7

Which actin binding proteins are involved in cross-linking?

Answer 7

Spectrin, filamin, adductin, protein 4.1, protein 4.9. Important for actin cortex. A specter filled a duct with 4 proteins.

Question 8

Which actin binding protein are involved with filament severing?

Answer 8

Gelsonin

Question 9

Which actin binding proteins are involved in capping? What does capping do to actin filaments?

Answer 9

Tropomodulin. Stops growth at + end.

Question 10

Which actin binding proteins are involved in motor?

Answer 10

Myosins I- IX.

Question 11

T or F. Intermediate filaments are structurally and biochemically homologous.

Answer 11

False. Intermediate filaments are structurally homologous but biochemically different.

Question 12

Name 3 functions of intermediate filaments.

Answer 12

1. Maintenance of cell shape
2. Anchorage of nucleus and other organelles.
3. Formation of nuclear lamina.

Question 13

How thick is an actin filament? Intermediate filament? Microtubule?

Answer 13

1. Actin: 2nm.
2. Intermediate filament: 8-12 nm.
3. 25 nm.

Question 14

______ ________ ________ allow epidermal cells to resist stress. (3 words)

Answer 14

Cytokeratin intermediate filaments.

Question 15

Class I Intermediate filaments: Name 1 component polypeptide and the corresponding location where the filament is found.

Answer 15

Component polypeptide: acidic and basic cytokeratins.

Location: All epithelial cells.

Question 16

Class II Intermediate filaments: Name 3 component polypeptides and the corresponding locations where the filament are found.

Answer 16

1. Polypeptide: Vimentin, Location: Cells of mesenchymal origin (endothelium, myofibroblasts, smooth muscle)
2. Polypeptide: Desmin, Location: Muscle.
3. Glial fibrillary acidic protein, Location: Glial cells (Astrocytes, Schwann cells)

Question 17

Class III Intermediate filaments: Name 1 component polypeptide and the corresponding location where the filament is found.

Answer 17

Polypeptide: Neurofilament proteins, Location: Neurons.

Question 18

Class IV Intermediate filaments: Name 1 component polypeptide and the corresponding location where the filament is found.

Answer 18

Polypeptide: Nuclear lamins A, B, C. Location: Nuclear lamina of all cells.

Question 20

Microtubules are composed of _____ and ______ tubulin dimers.

Answer 20

Alpha, Beta

Question 21

T or F. Like actin, microtubules grow only at the + end and shortens only at the - end.

Answer 21

False. Microtubules can also shorten at the + end.

Question 22

The - end of a microtubule is embedded in the ____________.

Answer 22

Microtubule organizing center (MTOC)

Question 23

T or F. Kinesin and dynein are ATPases.

Answer 23

True.

Question 24

Kinesin is an ______ motor.

Answer 24

Anterograde, it moves from - to +.

Question 25

Dynein is a _______ motor.

Answer 25

Retrograde, moves from + to -.

Question 26

What are the 3 different surfaces of an epithelial cell?

Answer 26

Apical, lateral, basal.

Question 27

Microvilli are composed of which filament?

Answer 27

Actin.

Question 28

What is a consequence of Microvillus Inclusion Disease?

Answer 28

Inability to absorb nutrients, refractory diarrhea.

Question 29

Cilia in the human trachea help _____________.

Answer 29

Moves fluid/material over the epithelium.

Question 30

What is a basal body?

Answer 30

A nucleating center for microtubules.

Question 31

How is a ciliary axoneme organized?

Answer 31

9 + 2 organization.

Question 32

Ciliary axonemes move by _______ (dynein or kinesin) dependent hydrolysis of ATP.

Answer 32

Dynein.

Question 33

A ciliary axoneme suffering from Kartegener's Syndrome lacks ______.

Answer 33

Dynein arms.

Question 34

T or F. Like most cilia, stereocilia is made of microtubules. Where are stereocilia located?

Answer 34

False. They are actually long microvilli and are made up of actin. Located on epididymis and hair cells of cochlea.

Question 35

How does kinocilia differ from typical cilia? Where can you find kinocilia?

Answer 35

Kinocilia is nonmotile and organized 9 + 0. It is present on hair cells of inner ear.

Question 36

The _______ (apical, lateral, basal) wall is heavily involved in adhesion.

Answer 36

Lateral.

Question 37

What are functions of Tight Junctions?

Answer 37

1. Prevents passage of water soluble molecules 2. Prevents movement of integral membrane proteins. 3. Connects cells to neighbors 4. Maintains gradients.

Question 38

Tight junctions consists of a complex of proteins which include _____ and _____.

Answer 38

Occludin, claudin.

Question 39

Name 2 types of anchoring junctions (anchor between cells).

Answer 39

Adherens junctions. Desmosomes.

Question 40

What are the components of the adherens junction?

Answer 40

Ca2+ dependent adhesive interactions mediated by cadherin proteins. Actin filaments anchored via catenin and vinculin.

Question 41

What are the components of desmosomes?

Answer 41

Adhesive action mediated by desmoglein and desmoplakin. Intermediate filaments anchored to desmoplakin/pakoglobin attachment plaque.

Question 42

Gap junctions are channels composed of ______.

Answer 42

Connexons (connexons are made of 6 connexin subunits).

Question 43

What are 2 functions of gap junctions?

Answer 43

1. Allows passage of ions and small molecules between cells. 2. Couples cells electrically and metabolically.

Question 44

What are 3 functions of basement membranes and Cell-to-Extracellular Matrix connection?

Answer 44

1. Support 2. Adhesion 3. Filtration

Question 45

What are 4 major components of basement membrane/cell-to-extracellular matrix connections?

Answer 45

1. Laminin 2. Type IV collagen 3. Entactin 4. Perlecan

Question 46

What are integrins? What do they do?

Answer 46

Transmembrane proteins consisting of a/b heterodimer. Important in signal transduction via coupling to second messenger systems.

Question 47

Alpha chains of integrins bind to ...?

Answer 47

Alpha chains mediate adhesion by binding to short recognition sequences on ECM molecules such as laminin, fibronectin and collagen.

Question 48

The integrin cytoplasmic doman is coupled to _____ cytoskeleton.

Answer 48

Actin.

Question 49

What is Pemphigus and what are symptoms?

Answer 49

Autoimmune disease directed against components of desmosome and hemidesmosome. Epidermal blistering and loss of extracellular fluids

Question 50

What is Alport's Sydrome and what are symptoms?

Answer 50

Inherited defect in structure of Type IV collagen. | Symptoms include hematuria

Question 69

Name 4 functions of microtubules.

Answer 69

1. Cell shape 2. Organelle movement 3. Chromosome movements in cell division 4. Cell motility