Lecture 11 part 1

Question 1

What is cell communication?

Answer 1

Direct interactions between cells, as well as between cells and the extracellular matrix.

Question 2

Why is cell communication critical?

Answer 2

For the development and function of multicellular organisms.

Question 3

How does cells communicate?

Answer 3

By sending and receiving signals, variety of chemical and mechanical signals.

Question 4

What is cell adhesion?

Answer 4

Process by which cells form contacts with each other through specialized protein complexes.

Question 5

Cells of most tissues are bound directly to one another by?

Answer 5

cell-cell junctions.

Question 6

why extracellular matrix is important?

Answer 6

Cells can interact with extracellular matrix through cell
membrane molecules, mostly integrins, which are
transmembrane adhesion proteins.

Question 7

What is extracellular matrix made of?

Answer 7

ECM is a scaffold of proteins and carbohydrates located around cells.

Network of polysaccharides (such as
glycosaminoglycans) and proteins (such as collagens)
secreted by cells. Based on protein-protein interactions
and protein-carbohydrate adhesions.

Question 8

What are collagens?

Answer 8

Collagens are a family of proteins found in mammals, take to 25% of the total protein content of the body.
Characterized by high strength and resistance to pulling forces.

Question 9

What is elastin?

Answer 9

Insoluble polymer made up of proteins that form

part of the elastic fibers.

Question 10

What are glycosaminoglycans?

Answer 10

A family of large polymers containing a repeat disaccharide structure, most often attached to a core
protein forming a proteoglycan.

Question 11

What are fibronectins?

Answer 11

Multidomain glycoproteins consisting of two polypeptides joined by disulfide bridges.

Question 12

ECM + fibronectins regulate?

Answer 12

ECM interact with cells through crucial connections with the fibronectin to regulate cell adhesion, migration and differentiation.

Question 13

What are laminins?

Answer 13

Laminins are a family of large, mosaic glycoproteins. Laminins mediate interactions between cells via cell surface receptors.

Question 14

What is glycocalyx?

Answer 14

Glycocalyx (the cell coat) is a layer of glycoproteins and sugars on the extracellular face of the plasma membrane of most cell types.

Question 15

What does the composition of the glycocalyx influences?

Answer 15

Properties of the cell membrane:
➢adhesion,
➢cell-cell recognition,
➢signalling.

Question 16

What are tight junctions?

Answer 16

Cell–cell junction that seals adjacent epithelial
cells together.
Preventing the passage of most dissolved molecules from one side of the epithelial sheet to the other.

Question 17

What are gap junctions?

Answer 17

Communicating cell–cell junction that allows ions
and small molecules to pass from the cytoplasm
of one cell to the cytoplasm of the next.

Question 18

What are anchoring junctions?

Answer 18

Adherens, desmosome and hemidesmosome.

Adherens: cell junction in which the cytoplasmic face of the plasma membrane is attached to actin filaments..

Desmosome: usually formed between two epithelial cells, characterized by dense plaques of protein linked with intermediate filaments.

Hemidesmosome: specialized anchoring cell junction between an epithelial cell and the underlying extracellular matrix.

Question 19

What proteins does extracellular matrix consists of?

Answer 19

Collagen and elastin

Question 20

What polymer does the extracellular matrix consists?

Answer 20

Glycosaminoglycans.

Question 21

What glycoproteins does the extracellular matrix consists of?

Answer 21

Fibronectin and laminins.