Lecture 7 - Exam

Question 1

What are the simplest organizational structure that has attributes of life?

Answer 1

Cells

Question 2

What does being alive mean?

Answer 2

To be a cell or be composed of cells?

Question 3

What is built up to get to organisms?

Answer 3

cells -> tissues -> organs -> systems -> organisms

Question 4

What allows organism to carry out essential activities?

Answer 4

The coordinated functioning of cells that make up higher orders of organization - form follows function

Question 5

What happens in pathological tissue or tumor cells?

Answer 5

Loss of organization of the cells

Question 6

What are tissues?

Answer 6

Aggregates of cells organized to perform one or more specific functions

Question 7

What are the 4 main tissue types?

Answer 7

Epithelial, connective, muscle, nerve

Question 8

How is epithelium organized?

Answer 8

Sheets of cells that may be flat or folded into pleats, tubes, spheres - adjacent cells directly attached and have apical top and basal bottom

Question 9

What is the purpose of epithelium?

Answer 9

Line or cover organ surfaces and regulate transport of materials and form glands

Question 10

How are the subtypes of epithelium classified? and what are some examples?

Answer 10

Thickness and shape of cells, cuboidal and columnar

Question 11

What is connective tissue made up of?

Answer 11

Formed by combination of cells and an extraceullar macromolecular complex of proteins

Question 12

What is the purpose of connective tissue?

Answer 12

To form skeletal structures, provide conduit for blood vessels and nerve, make attachment and support structure, fill in spaces and provide cushioning

Question 13

How are connective tissue subtypes determined?

Answer 13

Composition and organization of ECM and cell populations vary

Question 14

What are the types of muscle tissue?

Answer 14

Skeletal, smooth, cardiac

Question 15

What is the specialized function of all muscle tissue?

Answer 15

Contraction

Question 16

What is nerve tissue specialize for?

Answer 16

Transmission of electrical signals which regulate brain function, muscle and gland activity

Question 17

What are the two major cell types of nerve tissue?

Answer 17

Neurons - the cells that generate and receive electrical signals
Glia - mixed population of cells that provide metabolic and structural support to neruons

Question 18

What two things must cells have to work as a tissue?

Answer 18

Cohesion - including adhesion, common function and distribution of force and
Communication - including small molecule exchange and electrical coupling and signaling pathways

Question 19

What are the major kinds of adhesive interactions?

Answer 19

Cell-cell junctions - to provide a barrier, hold cells together, link the cytoskeleton of adjacent cells, allow intracellular movement of small molecules
Cell-matrix interactions - adhesions that attach cells to their extracellular matrix permanently or transiently

Question 20

How are adhesive interactions mediated?

Answer 20

Cell-Adhesion Molecules - CAMs - proteins located on cell surface involved in binding - typically transmembrane receptors that bind molecules from adjacent cells or ECM

Question 21

What are the 4 families of CAMs?

Answer 21

Immunoglobulin superfamily (IgSF CAMs), Integrins, Cadherins, and Selectins

Question 22

Which CAMs perform homophilic interactions and which perform heterophilic?

Answer 22

Homophilic - Cadherins and IgSF

Heterophilic - Integrins and Selectins

Question 23

What are the domains of CAMs?

Answer 23

Intracellular domain to interact with cytoskeleton
Transmembrane domain
Extracellular domain to interacts with other CAMs either homophilically or heterophilically

Question 24

What is cis (lateral) binding and what is trans binding?

Answer 24

Cis is the adhesions of cells on the same membrane (same cells - intra) and trans is the adhesion of cells on different plasma membranes (one cell to another - inter) - cis and trans can be combined

Question 25

Which CAM does cell-matrix adhesions?

Answer 25

Integrins (sometimes does cell-cell)

Question 26

Which surfaces on cells have more transient adhesive interactions and which have more long lasting?

Answer 26

Transient - apical

Long lasting - lateral and basal

Question 27

What is zonula occuludens?

Answer 27

Tight junctions - a type of lateral cell-cell adhesive interaction - it is the most apically located, it is a belt that encircles the entire cell - and is formed by numerous membrane fusions - compartmentalize integral membrane proteins into apical and basolateral domains, and prevent free flow of water soluble molecules between cells from apical to basal (paracellular)

Question 28

What are the proteins that mediate tight junctions?

Answer 28

Occludins, claudins (most crucial in determining tightness), JAMs, and tricellulin

Question 29

What is paracellular pathway versus transcellular pathway?

Answer 29

Paracellular is the free flow between two cells, the transcellular is flow through one cell

Question 30

What is zonula adherens?

Answer 30

Adhering junctions - a type of lateral cell-cell adhesive interaction - encircle the cell circumference basal to the zonula occludens - give 15-20 nm between plasma membranes of cells

Question 31

What is the function of zonula adherens?

Answer 31

Cell adhesion - link actin cytoskeletons of adjacent cells

Question 32

What mediates zonula adherens?

Answer 32

Cadherin - to allow extracellular domains to interact or intracellular domains to link to actin cytoskeleton via catenins

Question 33

What do you need for zonula adherens to form?

Answer 33

Cadherin and calcium - the cadherins are calcium dependent

Question 34

What is epithelial-mesenchymal transition? And what is an example?

Answer 34

When cells lose epithelial characteristics which allow them to move around more freely - they lose E-cadherin activity and this promotes cancer and mestastisis

Question 35

What is macula adherens?

Answer 35

Desmosomes - a type of later cell-cell adhesion interaction - located basal to the belt junctions and distributed randomly along the lateral membrane domain - discrete spot adhesions

Question 36

What is the function of macula adherens?

Answer 36

To provide strong spot adhesions between cells - site of intermediate filament insertion on intracellular attachment plaques

Question 37

What are the belt junctions and in what order do they appear?

Answer 37

Occludens and adherens with occludens being more apical

Question 38

What are the communicating junctions?

Answer 38

Gap junctions - a type of later cell-cell adhesion junction

Question 39

Where are gap junctions found and what comprises them?

Answer 39

Located randomly along lateral membranes, comprised of packed connexons which are composed of connexins (integral membrane proteins) - from 2-3 nm intercellar channel between the two connexon plaques

Question 40

What are basal cell-matrix adhesions?

Answer 40

Hemidesmosomes and focal adhesions

Question 41

What do hemidesmosomes do and what are they made up of?

Answer 41

Attach the basal cell membrane to the basal lamina - involved in stabile, long-term attachments, site of keratin tonofilament attachment (IF)

Question 42

What mediates hemidesmosome interactions?

Answer 42

Integrins which link the cell cytoskeleton to the extracellular matrix molecules in the basal lamina (like laminin and type IV collagen) providing adhesion, traction and bidirection signaling - only one attachment plaque

Question 43

What is the structure of integrins?

Answer 43

Alpha and beta subunits to form dimer - extracellular domain binds ligands, transmembrane domain, cytosolic (intracellular) domain binds the cytoskeleton - allows for outside-in signaling and inside-out signaling - bidirectional

Question 44

What do focal adhesions do and what is their structure?

Answer 44

Attach basal cell membrane to the basal lamina, involved in dynamic, transient attachments, site of actin filament attachment, mediated by integrins that recognize R-G-D motif - used to pull forward like in lamelipodia

Question 45

What is analogous to integrin in term of it’s function in skeletal muscle cells?

Answer 45

Dystrophin glycoprotein complex (DGC) - binds laminin in basal lamina

Question 46

What are the apical cell-cell adhesive interactions?

Answer 46

Selectins

Question 47

What are the lateral cell-cell adhesive interactions?

Answer 47

tight junctions (occulens), adhering junctions (adherens), desmosomes (macula adherens), and gap junctions

Question 48

What are selectins? and their structures?

Answer 48

An apical cell-cell adhesive interaction that mediate leukocyte - vascular cell interactions, involved in dynamic attachments and have a calcium dependent lectin domain and bind to sugars in glycoproteins

Question 49

What is margination?

Answer 49

Selectins sit on vasculature and leukocytes are in resting state with selectin ligands/carbohydrates on outside of membrane - transiently attaches to selectin which slows leukocyte rolling motion down, until integrin on leukocyte membrane attaches to ICAM on vasculature and once it is firmly attached it squeezes through cells in the vasculature (extravasation) – heterophilic interactions occurring

Question 50

What does loss of cell adhesion lead to?

Answer 50

Cancer metastasis, skin blistering conditions, inflammation, heart arrhythmia

Question 51

What factors in adhesion lead to cancer’s invasive behavior?

Answer 51

Integrin signaling down regulates E-cadherin to allow for augmented increased cell motility, and integrin upregulates matrix metalloproteinases (MMPs) to degrade matrix components in basal lamina
Laminin has abnormal expression that promotes migration

Question 52

What can compromise junctional complexes?

Answer 52

Pathogens in the gut like clostridium perfringens and heliobacter pylori which binds to zonula occludins to make them nonfunctional - can lead to ulcers
Alcohol toxins can lead to intestinal hyper-permeability or leaky gut syndrome