Cell Junctions

Question 1

Name the four different anchoring junctions in cells, say whether they are cell-cell or cell-matrix

Answer 1

1. Adherens junctions (cell-cell)
2. Desmosomes (Cell-cell)
3. Hemidesmosomes (cell-matrix)
4. Focal contacts (cell-matrix)

Question 2

Adherents junctions are connected to the ___________ membranes. They are located near the _________ surface.

Their structure of adherents is like a _________, which acts with ____________ to form a ____________ to brace the cell and control the shape
.

Answer 2

Adherents junctions are connected to the LATERAL (SIDE-TO-SIDE) membranes. They are located near the APICAL surface.

Their structure of adherents is like a BELT ROUND THE CELL, which acts with ACTINS AND MICROFILAMENTS to form a _A TENSION CABLE to brace the cell and control the shape

Question 3

What are the three main parts that make up cellular junctions? What do they do?

1 ___________ - in the plasma membrane to connect ________________.
2. ____________ - connect the CAMs to ____________ or cytoskeletal filaments.
3. _________________.

Answer 3

1. Adhesive proteins (CAMs) - in the plasma membrane to connect from one cell to another
2. Adapter proteins - connect the CAMs to adhesion receptors or cytoskeletal filaments
3. Cytoskeletal filaments

Question 4

What are the two specialised cadherins in desmosomes?

Answer 4

1. Desmoglein
2. Desmocollin

Question 5

Put these in order:

1. Desmoglein/desmocollin
2. Desmoplakin
3. Plakoglobin/plakophillins
4. Intermediate filaments
5. Desmosomes

__________ are connected to ___________

Answer 5

5, 1, 3, 2, 4

Question 6

What is Pemphigus vulgaris?

Answer 6

Pemphigus vulgaris is a:
1. Human autoimmune disease
2. Disrupts desmosome adhesion between epithelial cells
3. Causes blisters of skin and mucous

Question 7

Tight junctions prevent the diffusion of _________ across an epithelium.

They also seal off ____________.

Answer 7

Tight junctions prevent the diffusion of MACROMOLECULES, WATER-SOLUBLE MOLECULES AND IONS across an epithelium.

They also seal off BODY CAVITIES.

Question 8

The structure of tight junctions is _________ and __________.

They are formed of rows of ______________ linked together.

Answer 8

The structure of tight junctions is APICAL and EXOPLASMIC.

They are formed of rows of PROTEIN PARTICLES linked together.

Question 9

What are the two integral membrane proteins?

Answer 9

Occludin and claudin

Question 10

Paracellular pathway
Tight junctions create a ________ that controls the passage of molecules through the ______________.

The Paracellular pathway will only let ________ and ________ move through.

Many nutrients alternatively travel through the _____________ which goes through the cell rather than externally.

Answer 10

Paracellular pathway
Tight junctions create a BARRIER that controls the passage of molecules through the PARACELLULAR PATHWAY.

The Paracellular pathway will only let SMALL MOLECULES and WATER move through.

Many nutrients alternatively travel through the TRANSCELLULAR PATHWAY which goes through the cell rather than externally

Question 11

Gap junctions allows small molecules to pass between _________ of adjacent cells.

Gap junctions are composed of __________ . Six dumbbell-shaped ________, create make up one __________, creating a “tunnel” that connects on other cells.

Gap junctions enable ________, __________ and __________ to pass through.

Answer 11

Gap junctions allows small molecules to pass between CYTOSOLS(CYTOSPLASM) of adjacent cells.

Gap junctions are composed of CONNEXINS. Six dumbbell-shaped CONNEXINS, make up one CONNEXON, creating a “tunnel” that connects on other cells.

Gap junctions enable IONS, SMALL MOLECULES and SIGNAL MOLECULES to pass through.