Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cell biology > Week 7: Cell cell jxns > Flashcards

Week 7: Cell cell jxns Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

cell junctions

A

structurally and functionally diverse which can be classified into several groups

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

anchoring junction

A

mediate cell/cell and cell/matrix interactions as the contact between cells
- adherens junctions
- desmosomes
- hemidesmosomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

adherens junction

A

connects actin filament bundles in one cell with another cell via cadherins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

desmosomes

A

connects intermediate filaments in one cell to those in the next cell via cadherins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

hemidesmosomes

A

anchors intermediate filaments in cell to extracellular matrix via integral and collagen types

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

occluding junctions

A

seal the gaps between epithelial cells
- tight junctions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

tight junction

A

seals the gap between epithelial cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

channel forming junctions

A

form passageways between neighboring cells
- gap junctions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

gap junction

A

allows the passage of small water-soluble molecules from cell to cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

which side is the extracellular matrix on? Basal or Apical

A

basal lamina side

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

intracellular adaptor proteins

A

proteins on the inside of the cell that either link to another transmembrane protein between the two cells or between the cell and the ECM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

transmembrane adhesion proteins

A

proteins that directly link either two cells or link the cell to the extracellular matrix
- they are all transmembrane proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

cytoskeletal filaments

A

intracellular domains of transmembrane adhesion proteins get lined with this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

actin linked cell matrix junction

A

anchors actin filaments in a cell to extracellular matrix via integrin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

cadherin vs integrin

A

cadherin forms cell to cell junctions via actin or intermediate filaments while integral forms cell to matrix junctions via actin or intermediate filaments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Chelated

A

something that will bind the calcium ions and remove it from an organism
- happens with EDTA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Ca2+ dependent

A

non functional when Ca2+ is chelated
- cadherin domains are mediated by Ca2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what 2 things does Ca2+ mediate?

A
  1. homophilic adhesion (the same cadherin molecules bind to itself (E to E and N to N)
  2. selective cell sorting where the same groups of cells expressing certain amounts of cadherins will bind to themselves (high cell expression goes to the middle clump)
19
Q

anchoring junction and cadherins

A

cadherins form clusters and accumulate many weak bonds which form a strong junction like a velcro effect

20
Q

aggregates

A

mixtures of cells expressing two different cadherins will sort into individual clumps
-E cad vs N cad clumps

20
Q

how are cadherins involved in animal cell sorting?

A

amphibian embryos were dissociated into single cells and the cells were mixed so they could re-associate. The cells reassembled into structures like the original embryo
- neural plate cells on the inside, mesoderm cells in the middle, and epidermal cells on the outer layer
- the same cell types associated together in aggregates

21
Q

what happens when cells have different levels of promotor expression of the same cadherin?

A

the two cell types will express different levels and aggregate with the high expression E cells in the middle and lower expression E cadherin cells on the outside

22
Q

what 2 things explain cell aggregates?

A
  1. types of cadherin
  2. expression of cadherin
23
Q

adaptor proteins

A

these link to the intracellular domain of the cadherin and then also link to actin filaments
- this forms the complex for cell-cell adhesion
- form of indirect binding between cadherins and actin filaments

24
Q

types of adaptor proteins from class (4)

A
  • p120 catenin linking directly to cadherin
  • beta cetenin which also links directly yo cadherin
  • alpha catenin which links to beta catenin and some actin filaments
  • vinculin which links to alpha catenin and actin filaments
25
Q

how does cortical tension aid formation of adherens junctions?

A

small cadherin clusters send a message to the cellular cortex and tell actin to dissociate, the cadherins signal to inhibit Rho and activate Rac which disassembles actin myosin fibers and loses cortical tension, recruitment of more cadherins helps the spread of the cell to cell junction
- Rho and Rac are GTPases involved in actin myosin assembly

26
Q

continuous adhesion belt

A

in epithelial cells, adherent junctions are connected as homophilic and calcium dependent binding that interact with adaptors and actin filaments
- the actin filament goes to the other side of the cell and connected to the junctions on the other side of the cell as well which makes it continuous

27
Q

invagination of actin

A

this contraction of the network provides the force required to fold epithelial sheets during development
- the adhesion belt is organized to tighten in certain regions of the cell

28
Q

tube formation

A

invagination of the epithelial cells will pinch off to form a tube underneath the overlying sheet of epithelial cells
- the basal side is together while the other side is not and the apical side can be contracted to be more narrow

29
Q

desmosomes and cadherins

A

clusters of cadherins form plaques that link the intermediate filament and use similar structure as adherent junctions but different types of cadherins
- nonclassical cadherin proteins

30
Q

what are the cadherin types (2) used in desmosomes?

A

desmoglein and desmocollin

31
Q

what are the adaptor proteins used in desmosomes?

A
  1. plakophilin binds directly do cadherin
  2. plakoglobin binds to cadherin and plakophilin and desmoplakin
  3. desmoplakin binds to plakoglobin and the intermediate filaments
32
Q

what is the structural framework function desmosomes provide?

A

they provide mechanical strength (often the intermediate filament is keratin)

33
Q

how do tight junctions organize epithelial cells?

A

with the apical side of occludin junction they connect each cell and strictly seal them together
- this prevents glucose from leaking back into the gut lumen instead of moving toward the blood

34
Q

basal lamina (basement membrane)

A

thin membrane sheet sealed together by tight junctions such as in the gut epithelium

35
Q

describe glucose trancellular transport

A
  1. Na+ driven glucose transporter are on the apical membrane and uptake glucose into the cell
  2. passive glucose transporters are on the basolateral membrane and exposed glucose goes to the basal side where it is passed to the basal lamina and into the blood with the ECM fluid and connective tissue
36
Q

functions of tight junctions

A
  1. Diffusion barrier: transported molecules cannot leak back
  2. Fences: within the membrane are apical (BL) transmembrane proteins that cannot diffuse into the other side
37
Q

what 2 proteins compose tight junctions?

A

adhesion transmembrane proteins Claudin and occludin (intercellular space)
- the two cells match together so that small molecules cannot pass between them

38
Q

intercellular space

A

between cells which becomes occluding in the area of the tight junction
- the plasma membranes are brought into close proximity

39
Q

how do gap junctions work?

A

they form cell to cell channels and allow small molecules 1,000 daltons or less into neighboring cells
- this couples the cells electrically and metabolically

40
Q

what proteins form the gap junction?

A

connexon proteins which involve 6 transmembrane connexin proteins assembled into a hemichannel to form the aqueous channel connecting the cytosol of the cells
- they may be homomeric or heteromeric

41
Q

homomeric vs heteromeric

A

connexons of all identical molecules vs connexions that have some different molecules
- forms homotypic (all 1 molecule) and heterotypic which may have different molecules anywhere in the connexion

42
Q

what functions do gap junctions have? (2)

A
  1. action potentials in nerve cells where pulses spread rapidly from one cell to another
  2. coordinated cell responses in cells that are not electrically excitable
43
Q
A

Cell biology (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions