ECM and cell junctions

Question 1

??? refers to the biological structures at the interface between cells with different types that govern tissue structure and functioning

Answer 1

junctions

Question 2

junctions are critical for maintaining ??? integrity of cells as well as permeability and communication

Answer 2

structural integrity

Question 3

What is the extracellular matrix?

Answer 3

it is the scaffold of molecules within a tissue that surrounds and provides structural support to cells

Question 4

what is critical for mechanical support of cells, cell behaviour and tissue repair?

Answer 4

the extracellular matrix

Question 5

??? mediates cell to ECM interactions

Answer 5

integrins

Question 6

??? refers to the biomolecular components that exist within tissues but outside cells as an organised network of material beyond the cell plasma membrane

Answer 6

the extracellular matrix

Question 7

the composition of the ECM varies in different tissue types but typically is composed of ??? and polysaccharides

Answer 7

proteins

Question 8

with what type of membrane-spanning proteins are cells connected to the ECM?

Answer 8

integrins

Question 9

what are the two main forms of ECM?

Answer 9

basement membrane (aka basal lamina) and connective tissue

Question 10

which one- the basement membrane or connective tissue- is a continuous layer providing specialised, supportive foundation for epithelial and endothelial cells?

Answer 10

basement membrane

Question 11

which one- the basement membrane or connective tissue- surrounds muscle and fat cells to provide mechanical support and separates tissue/organs and enables cell migration?

Answer 11

basement membrane

Question 12

which one- the basement membrane or connective tissue- is far more structurally diverse and includes dermis, cartilage, tendons, bone, teeth, cornea, mollusc shells, plant and fungal cell walls, etc?

Answer 12

connective tissue

Question 13

the three classes of ECM molecules are:
1. ??? proteins
2. Adhesive glycoproteins
3. proteoglycans with GAGs

Answer 13

1. Fibrous proteins

Question 14

which class of ECM provides strength, elasticity and rigidity to tissues, with collagen being the most common type of ECM molecule in this class?

Answer 14

Fibrous protein

Question 15

which class of ECM includes laminin and fibronectin (a glycoprotein that is post-translationally modified by addition of carbohydrates and facilitates adhesion between cells and ECM by attaching integrins to elastin or collagen)

Answer 15

adhesive glycoproteins

Question 16

ECM Class 3 Proteoglycans with GAGs consist of a core protein with ??? attached GAG chain

Answer 16

covalently

Question 17

ECM Class 3 Proteoglycans with GAGs have an increased or decreased negative charge due to sulphated GAGs binding cations which attracts water molecules = hydrated gel that fills extracellular space

Answer 17

increased

Question 18

Integrins are ??? proteins that span entire plasma membrane: Extracellular domain which binds to fibronectin with an internal domain that binds indirectly to actin

Answer 18

receptor proteins

Question 19

integrins provide mechanical resistance but also mediate ???

Answer 19

cell signalling

Question 20

the external and internal signals from environment cause conformational changes in ??? which changes or influences binding behaviour

Answer 20

integrins

Question 21

when integrins are in bent or extended state (?) they are active

Answer 21

extended state

Question 22

when integrins are in bent or extended state (?) they are inactive

Answer 22

bent

Question 23

integrins bind to ??? which bind to collagen

Answer 23

fibronectin

Question 24

TRUE or FALSE: A tight junction seals neighbouring cells together in an epithelial sheet to prevent movement of substances between cells

Answer 24

TRUE

Question 25

what type of junction causes cell to cell anchoring, tying together two cells via actin molecules of each cell and are mediated by cadherins?

Answer 25

adherens junction

Question 26

Desmosomes interact with ??? filaments of adjacent cells and are mediated by cadherins

Answer 26

intermediate filaments

Question 27

Gap junctions allow direct or indirect transfer of material such as small water molecules and ions between the cytoplasm of adjacent cells?

Answer 27

direct transfer.

Question 28

what is the role of hemidesmosomes?

Answer 28

cell matrix anchoring

Question 29

which type of junction is critical in maintaining selective permeability so that only certain molecules can be absorbed through via dedicated processes such as channels (i.e BBB)? Gap or Tight junctions?

Answer 29

tight junctions

Question 30

TRUE or FALSE tight junctions maintain polarity and asymmetry of a cell. e.g. in epithelia one side faces lumen (external environment) = apical, whilst the other side faces underlying tissue (internal environment) = basolateral. also ensures certain receptors are confined to apical or basolateral space

Answer 30

TRUE

Question 31

Cadherins bind together cells via their ??? e.g. in adherens junctions, cadherins bind to actin whilst in desmosomes they bind intermediate filaments

Answer 31

cytoskeletons

Question 32

do integrins or cadherins require Ca2+ for binding and typically mediate homophilic (same cells) binding?

Answer 32

cadherins

Question 33

which type of junctions is predominantly made with connexons and provide direct channels that traverse membranes of adjacent animal cells?

Answer 33

Gap junctions

Question 34

connexons are 6 subunits of ??? proteins

Answer 34

connexin

Question 35

are hemidesmosomes integrin or cadherin mediated? they bind to basal lamina via cytoskeleton, e.g. keratin

Answer 35

integrin

Question 35

do gap junctions or desmosomes allow water soluble molecules ~1000 Da to move directly from cytosol of one cell to the next, enabling electrical and metabolic coupling of cells? e.g cardiac tissue

Answer 35

gap junctions

Question 36

TRUE or FALSE: gap junctions can be opened or closed as needed in response to extracellular signals

Answer 36

TRUE

Question 37

In the case of basal lamina, which has an incontinous membrane that supports cells above it, hemidesmosomes ??? the cells to membrane

Answer 37

anchor

Question 38

What type of junction ensures certain receptors, channels etc. are confined to the apical or basolateral space?

Answer 38

Tight junctions