Brainscape's Knowledge GenomeTM

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


See full index

Molecular Cell Biology and Genetics > Cell Junctions > Flashcards

Cell Junctions Flashcards

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

What are the four types of cellular junctions?

A

Tight (or occluding) junctions
Cell-Cell Anchoring junctions
Gap (or communicating) junctions
Cell-Matrix Anchoring junctions

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

What is the general function of tight junctions?

A

Keep things out of the cell.

Form a permeability barrier.

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

What is the purpose of tight junctions in the blood epithelium and intestinal lumen?

A

Blood vessel epithelium, esp. in the brain. - to prevent substances in blood from leaking out

Intestinal lumen - to prevent water from outside the intestines from leaking in

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

What is the importance of transcellular transport across cells linked by tight junctions?

A

Transcellular transport enables the cell to move nutrients through the cell, establishing a gradient. Otherwise, cell couldn’t absorb anything.

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

Explain the process of paracellular transport.

A

Substances cannot cross the apical or basolateral membrane. Instead, they are passed through intercellular space between the cells.

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

What are the two general functions of anchoring junctions?

A

To attach cells and their cytoskeletons either to other cells or to the cell matrix.

To stabilize the cell against mechanical stress.

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

What are the different types of anchoring junctions?

A

Desmosomes
Adherens junctions

Actin-linked cell-matrix junction
Hemidesmosomes

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

What is the transmembrane protein found in adherens junctions

A) Nonclassical cadherins
B) Classical cadherins
C) Integrin
D) alpha-beta-integrin, type 17 collagen

A

B

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

What is the transmembrane protein found in desmosomes?

A) alpha-beta-integrin, type 17 collagen
B) Classical cadherins
C) Nonclassical cadherins
D) Integrin

A

C

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

What is the transmembrane protein found in actin-linked cell-matrix junctions?

A) Nonclassical cadherins
B) Classical cadherins
C) alpha-beta-integrin, type 17 collagen
D) Integrin

A

D

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

What is the transmembrane protein found in hemidesmosomes?

A) Nonclassical cadherins
B) alpha-beta-integrin, type 17 collagen
C) Integrin
D) Classical cadherins

A

B

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

What cytoskelelal element do desmosomes and hemidesmosomes bind?

A) Actin
B) Myosin
C) Intermediate filaments
D) Microtubules

A

C

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

What cytoskelelal element do adherens and actin-linked cell matrix junctions bind?

A) Actin
B) Myosin
C) Intermediate filaments
D) Microtubules

A

A

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

What role do selectins play in the interaction between white blood cells and endothelial cells?

A

WBC rolls along blood vessel. When its selectin contacts a specific sugar signal, it is allowed to leave the blood vessel.

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

Explain the relationship between desmosomes and pemphigus?

A

Antibodies against desmosomal cadherin are produced. Cells lose cell-cell adhesion, resulting in blistering.

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

What is the general function of gap junctions?

A

To allow small molecules and electric signals to pass through interacting cells

17
Q

What are the transmembrane proteins that form gap junctions?

A

Connexins
4 transmembrane proteins
6 together make a pore

18
Q

What are the 2 types of transmembrane proteins that form tight junctions?

A

Claudin and occludin

19
Q

What can pass through connexons?

A

Molecules less that 1000 Da in size

20
Q

Explain the relationship of GAGs to proteoglycans.

A

Proteoglycans are GAGs covalently attached to a protein. They are synth. on core proteins and have sugars attached to then in the Golgi.

21
Q

Describe the characteristics of glycosaminoglycans (GAGs).

A

One sulfated sugar, one uronic acid.
Pattern is repeated in a chain.
Absorbs lots of water to occupy space

22
Q

Which cells secrete the most matrix molecules of connective tissue?

A

Fibroblasts, chondroblasts (cartilage), osteoblasts (bone) and epithelium (basal lamina)

23
Q

What are the major components of the extracellular matrix

A

Glycoaminoglycans, proteoglycans, fibrous proteins

24
Q

Purpose of proteoglycans

A

Form specialized gel. Bind growth factors, protease + protease inhibitors.

25
Q

What are the special features of collagens that provide strength to the matrix?

A

Long stiff triple helix alpha chains
Gly- smallest aa, hydrophobic ixns
Hydroxyproline+hydroxyserine interchain bonds stabilize the triple helix

26
Q

What are three principal types of collagens?

A

Collagen I
Collagen II
Collagen V

27
Q

Explain how a deficiency in vitamin C reduces the stability of the triple helix and the stability of collagen.

A

A lack of vitamin C inhibits the hydroxylation of serines and prolines, destabilizing the collagen triple helices

28
Q

Identify the characteristic of elastin fibers that gives them their elasticity.

A

Kinked and cross-linked nature of fibers

29
Q

Explain the consequences of a mutation of the fibrillin gene, i.e. Marfan’s syndrome

A

Excessive growth of long bones
Tall stature
Weakened blood vessels, heart valves
Aortic dilation and rupture
Malformed cartilage and ligaments
Skeletal abnormalities

30
Q

Identify the tripeptide sequence in the fibronectin repeat that serves as a binding site to integrins.

A

Arg-Gly-Asp (RGD) sequence binds integrins.

31
Q

Identify the major glycoprotein and proteoglycan components of basal lamina.

A

Laminin is a major adhesive protein that binds cells to the basal lamina
Type IV collagen, Perlecan, Nigoden, Heparin Sulfate are also abundant

32
Q

Describe the functions of the basal lamina.

A

a. Molecular filter: Kidney glomerulus
b. Barrier for cell migration: Cancer
c. Cell migration: Neuromuscular Junction
d. Cell orientation is reciprocally regulated by fibronectin fibrils and cytoskeleton
e. Cell survival: Anchorage Dependence is mediated by integrins

33
Q

Describe the basic structure of integrins.

A

Transmembrane heterodimer of alpha- and beta- glycoproteins (24 types, 9 types). Ligand binding is Ca2+ or Mg2+-dependent. Focal contact.

34
Q

Identify the intracellular proteins to which integrins attach and predict their importance to the strength of the association.

A

Fibronectin
Laminin
Important, as these are the most abundant proteins in the ECM. These allow the cells to remain attached to ECM

35
Q

Distinguish between inside-out signaling and outside-in signaling

A

Inside-Out Signaling
Inactive integrins are activated by the cells
a. Platelets activate 3 integrin to bind fibrinogen and cause aggregation
b. T lymphocytes active 2 integrins to bind antigen presenting cells

Outside-In Signaling

a. Clustering of integrins at ECM contact sites activates signaling
b. Focal Adhesion Kinase (FAK) is recruited and activated.
c. Similar to conventional growth factor receptors

Molecular Cell Biology and Genetics (13 decks)

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