11: Tissue Architecture

Question 1

Microfilament structure

Answer 1

F-actin filaments; form plus and minus ends

Question 2

Stability of microfilaments

Answer 2

Generally unstable but many different proteins bind to it to help stabilize and strengthen it

Question 3

Microfilament functions

Answer 3

Cell movements: locomotion, phagocytosis, division, contraction, etc.

Question 4

Three drugs that affect actin filaments

Answer 4

Phalloidin, Cytochalasin, Latrunculin

Question 5

Phalloidin

Answer 5

Binds and stabilizes microfilaments -> used in lab attached to fluorescent proteins to visualize cell shape

Question 6

Cytochalasin

Answer 6

Caps microfilament plus end, preventing polymerization

Question 7

Latrunculin

Answer 7

Binds actin monomers, preventing polymerization

Question 8

Microtubule structure

Answer 8

Alpha and beta tubulin subunits form microtubules with plus and minus end; forming long, stiff tubes with a hollow core

Question 9

Microtubule function

Answer 9

Organization

Question 10

Five drugs that affect microtubules and what theyre all three typically used for

Answer 10

Taxol, Colchicine, colcemid, vinblastine, vincristine: all for cancer tx

Question 11

Taxol

Answer 11

Binds and stabilizes microtubules

Question 12

Colchicine, colcemid, vinblastine, vincristine function

Answer 12

Bind tubulin dimers, preventing dimerization -> inability to pull chromatids apart during cell division

Question 13

Structure of intermediate filaments

Answer 13

Lamin proteins form rope-like filaments with high tensile strength

Question 14

Two things accessory proteins can do to intermediate filaments

Answer 14

1. Cross link filaments into bundles

2. Link intermediate filaments to microtubules, actin, and cell junctions

Question 15

Two types of intermediate filaments and their general function

Answer 15

Cytoplasmic: cell specific
Nuclear: form the nuclear lamina

Question 16

Three examples and cytoplasmic filaments and where theyre located

Answer 16

Keratin: in epithelium
Vimentin filaments: in CT, muscles, neuroglia
Neurofilaments: in neurons

Question 17

Nuclear lamina

Answer 17

Mesh-like structure under the nuclear envelope formed by nuclear intermediate filaments

Question 18

Main protein in the ECM

Answer 18

Collagen

Question 19

Collagen structure

Answer 19

Trimeric protein that forms fibers, sheets, or transmembrane structures

Question 20

Collagen synthesis steps

Answer 20

1. In ER: hydroxylation of P and K residues
2. In ER: glycosylation of K residues
3. In Golgi: packaged and prepared for secretion in secretory vesicles

Question 21

What two cofactors are required for collagen synthesis (the hydroxylation part)?

Answer 21

Fe, Vitamin C

Question 22

Some collagen-related symptoms of scurvy

Answer 22

1. Decreased wound healing
2. Loss of teeth
3. Anemia
4. Pale skin
5. Sunken eyes

Question 23

Four types of cell junctions

Answer 23

1. Anchoring junctions
2. Occluding junctions
3. Channel-forming junctions
4. Signal-relaying junctions

Question 24

Three types of anchoring junctions

Answer 24

Adherens, desmosomes, hemidesmosomes

Question 25

Anchoring junction 2 functions

Answer 25

1. Links cells together | 2. Strengthens contact between cells + ECM

Question 26

Occluding junctions: one type

Answer 26

Tight junctions

Question 27

Occluding junctions: function

Answer 27

Seals gap between cells -> barrier impermeable to diffusion

Question 28

Channel-forming junction: one type

Answer 28

Gap junction

Question 29

Channel-forming junction function

Answer 29

Link cytoplasm of adjacent cells -> allows transport

Question 30

Signal relaying junction: one example

Answer 30

Synapse

Question 31

Structure of integrins

Answer 31

15a + 8B subunits -> combine to form over 20 heterodimeric integrins

Question 32

Types of binding done by the Ig superfamily

Answer 32

Homophobic and heterophilic binding

Question 33

Structure differences between ICAM, VCAM, etc. and MAdCAM-1

Answer 33

ICAM/VCAM: variable # of Ig-like domains | MAdCAM-1: Ig-like domains + mucin-like domains

Question 34

Adherens: where and what is interacting

Answer 34

Latera adhesion; cadheren-actin interaction

Question 35

Desmosomes: where and what is interacting

Answer 35

Lateral adhesion; cadherens-intermediate filaments

Question 36

Hemidesmosomes: location and what is interacting

Answer 36

Basal interactions; integrins-intermediate filament interactions

Question 37

What type of cell junction is targeted in pemphigus vulgaris?

Answer 37

Desmosomes

Question 38

What end of a cell do occludens encircle cells?

Answer 38

Most apical side

Question 39

Two proteins involved in occluding junctions

Answer 39

Occludins, claudins

Question 40

Protein involved in channel-forming junctions (gap junctions)

Answer 40

Connexin aggregates

Question 41

Enzyme used to make collagen

Answer 41

Prolyl hydroxylase