Anatomy I: Cell Polarization

asymmetric

Cell polarization is _________ distribution of proteins, organelles, and cytoplasm.

1. Apical

2. Lateral

3. Basal

What are the three geometric domains of epithelial cells?

Apical domain

What domain is exposed to the lumen or external environment that may display apical membrane differentiations?

Lateral domain (walls)

Which domain faces neighboring cells and links to each other by cell adhesion molecules and junctional complexes?

Basal domain

Which domain is associated with the basement membrane?

Basal domain

Which domain separates cells from connective tissue and needs to be maintained?

1. Cilia

2. Flagella

3. Microvilla

4. Pseudopods

5. Glycocalyx

What structures are found in the apical domain?

1. Tight junctions

2. Adhering Junctions (Macula adherens and Zonula adherens)

3. Gap junctions

What structures are found in the lateral domain?

1. Hemidesmosomes

2. Focal adhesions

What structures are found in the basal domain?

Cilia are found in the apical domain

Cell movement is from microtubules driven by ATPase activity of dynein arms

Where are cilia found and what is responsible for their cell movement?

Basal body: is an organized structure made of nine sets of microtubule triplets arranged in a ring, lacking a central pair.

Microtubule: is an organized strucutre made of nine sets of microtubule doubletes arranged in a ring with a central pair in the middle

How does the structure of microtubules and basal bodies differ?

1. Found in the apical domain

2. Made of MT

3. Cilia move in synchrony

4. Use ATP for movement

What are the 4 important things to know about cilia?

1. Found in apical domain

2. Made of Actin filaments

3. DONT MOVE

4. Function is to increase SA of membrane

What are the 3 important things to know about microvilli?

microvilli

What structure is finger-like cytoplasmic projections in the apical domain?

cilia

What structure are hair-like extensions of the apical plasma membrane?

Apical domain

What is the pink border?

Lateral domain

What red/green border?

Basal domain

What the yellow border?

cilia

What is #1?

Microtubules

What is the structure pictured?

Basal Body

What is the structure pictured?

Microvilli

What is the structure pictured?

Microvilli

What is the structure pictured?

Microvilli

Which structure increases the SA of the apical membrane?

polysaccharide-base gel-like

What is glycocalyx?

1. Interface between the extracellular matrix and cellular membrane

2. Medium for cell-recognition, cell-cell communication (cell signaling) and cell attachment

What are the 2 functions of glycocalyx?

Glycocalyx

Which structure functions as cell recongition and communication?

Basal body

What is #2?

Cilia

What is A?

Microtubules

What is B?

Cell junctions

What general structure is mainly found in the lateral domain?

1. Occluding/Tight

2. Anchoring

3. Communicaiting/Gap

What are the 3 types of junctions?

Occluding/Tight junctions

What junction separates the basal and lateral apical domains?

Anchoring junctions

What junction has its main function of providing strength?

Communicating/Gap junctions

What junction allows the diffusion of small molecules and allows cells to function synchronously?

tight junction

What type of junction is zonula occludens?

They are tight junctions located at the apical end of the lateral membranes of adjacent cells

Where are zonula occludens found?

responsible for making a good barrier and restricting movement

What is the function of zonula occludens?

ZO proteins, occludin, Claudin and Jam

What are the components of zonula occludens?

1. Found in the apical end of the lateral region

2. Responsible for making a good barrier

3. Restrict movement (Tight Junctions)

What are the 3 important things about Zonula Occludens?

tight junctions (zonula occludens)

What is pictured?

tight junctions (zonula occludens)

What is pictured?

Zonula adherens (belt desmosome)

Which junction is used for adhesion and mechanical strength?

Zonula adherens (belt desmosome)

Which junction has complexes that interact with actin filaments?

1. Responsible for mechanical strength

2. Made of microfilaments (actin)

3. Wraps around the cell (belt desmosome)

What are the 3 things to know about Zonula adherens?

Macula adherens (Desmosomes)

Which junction is made of intermediate filaments?

Macula adherens (Desmosomes)

What is located below the belt desmosome junction?

Zonula adherens (belt desmosomes)

What is pictured?

Zonula adherens (belt desmosomes)

What is pictured?

Macula adherens (Desmosomes)

What is pictured?

1. Provide stability

2. Located below the belt desmosome junctions

3. Anchored using intermediate filaments

4. Found in the lateral domain

What are the 4 important things about macula adherens?

Cadherins

What cell adhesion proteins binding requires calcium?

1. Found in the lateral domain

2. Made of connexin

3. Allows exchange of ions and molecules (can open/close)

What are the important things to know about gap junctions?

1. Post-translational modifications

2. Redox potential

3. Voltage

What are the 3 controls of opening/closing gap junctions?

Gap junctions

What junction is made of transmembrane channels?

Gap junction

What junction is made of connexin?

Gap junction

What is pictured

Hemidesmosomes

What anchors intermediate filaments to the basement membrane?

Integrins bind the basal laminate

Plectins bind intermediate filaments

What are the 2 critical components of hemidesmosomes?

1. Anchor the intermediate filaments to the basement membrane

2. Found in the basal domain

3. Integrin binds basal lamina, plectins bind intermediate filaments

What are the 3 key takeaways for hemidesmosomes?

Zonula adherins (belt desmosomes; bind actin)

What are these structures?

Macula adherens (desmosomes; bind IFs)

What are these structures?

Hemidesmosomes

What are these structures?

basement membrane

Where is the collagen type VI found?

No, depends on cell type

Are all basement membranes the same?

1. laminate lucida (laminin)

2. Laminate dense (collagen IV)

3. reticular lamina (collagen I and III)

What is the basal lamina composed of?

Serves as an attachment site of epithelia to connective tissue

What is the main purpose of the basement membrane?

lamina lucida

1

lamina densa

2

Collagen Type VII

5

Fibrillin microfibril

4

laminate densa

Where is collagen IV found in the basement membrane?

reticular laminate

Where is collagen I and III found in the basement membrane?

1. Cell binds to the basal lamina (determines which side of the cell is basolateral and which is apical

2. Neighboring cells form a tight junction to establish and maintain this polarization, regulating protein trafficking

How does a cell become polar?