Lecture 7: Cell Matrix Interactions

Question 1

___________: the extracellular surface of the plasma membrane.

• Composed of carbohydrates ________ linked to membrane lipids and proteins
• Serves as a protective barrier
• Also important for enabling cells to ________ each other

Answer 1

Glycocalyx: the extracellular surface of the plasma membrane.

• Composed of carbohydrates covalently linked to membrane lipids and proteins
• Serves as a protective barrier
• Also important for enabling cells to Indentify each other

Question 2

4 Types of Tissue

Answer 2

• Epithelial
• Muscular
• Nervous
• Connective

Question 3

In _________ tissue cells are scanty but the extracellular matrix is plentiful and carries the mechanical load

Answer 3

In Connective tissue cells are scanty but extracellular matrix is plentiful and carries the mechanical load

Question 4

Animal Connective Tissues

• Tough and Flexible: ie __________
• Hard and dense ie __________
• Resilient and Shock absorbing ie __________
• Soft and transparent ie __________

Answer 4

Animal Connective Tissues

• Tough and Flexible: ie Tendons
• Hard and dense ie Bone
• Resilient and Shock absorbing ie Cartilage
• Soft and transparent ie Jelly that fills eye

Question 5

T/F the extracellular matrix can determine cell shape?

Answer 5

True

Question 6

The amount and composition of the extracellular matrix is what differentiates connective tissue T/F

Answer 6

True

Question 7

____________:

• A fibrous glycoprotein found only in ECM
• Produced by ________
• Very resistant to pulling forces
• •Provides the insoluble framework determining the mechanical properties of the matrix

Answer 7

Collagen:

• A fibrous glycoprotein found only in ECM
• Produced by fibroblasts
• Very resistant to pulling forces
• •Provides the insoluble framework determining the mechanical properties of the matrix

Question 8

What is the most abundant protein in the body?

Answer 8

Collagen

Question 9

__________:

• The main component of elastic fibers able to withstand pressure/pulling
• Collagen fibres are interwoven with elastic fibers to prevent tissue from tearing

Answer 9

Elastin:

• The main component of elastic fibers able to withstand pressure/pulling
• Collagen fibres are interwoven with elastic fibers to prevent tissue from tearing

Question 10

Extracellular matrix:

• A mixture of protein molecules and sometimes ______
• 2 functions?

Answer 10

Extracellular matrix:

• A mixture of protein molecules and sometimes minerals
• 2 functions
  
  • Provides a scaffold for cellular attachment
  • Transmits information in the form of chemical messengers to the cells to regulate migration, growth, and differentiation

Question 11

_________ produce the extracellular matrix of connective tissue

Answer 11

Fibroblasts produce the extracellular matrix of connective tissue

Question 12

________ Provides Tensile Strength in Animal Connective Tissue

Answer 12

Collagen

Question 13

Collagen molecules assemble into ordered polymers to form _____ and these can pack together into even thicker collagen _____

Answer 13

Collagen molecules assemble into ordered polymers to form FIBRILS and these can pack together into even thicker collagen FIBERS

Question 14

Incorrect collagen assembly can cause ________ skin

Answer 14

Incorrect collagen assembly can cause hyperextensible skin

Question 15

______ _______ play a role in many disease processes ranging from arthritis where they contribute to the breakdown of cartilage in affected joints and cancer where they help cells invade normal tissue

Answer 15

Matrix Proteinases play a role in many disease processes ranging from arthritis where they contribute to the breakdown of cartilage in affected joints to cancer where they help cells invade normal tissue

Question 16

________: negatively charged polysaccharide chains made of repeating disaccharide units that help fill space in the extracellular matrix of connective tissue. Absorb a lot of water

Answer 16

Glycosaminoglycans (GAGS): negatively charged polysaccharide chains made of repeating disaccharide units that help fill space in the extracellular matrix of connective tissue. Absorb a lot of water

Question 17

Chains of GAGs covalently linked to a core protein form _______

Answer 17

Chains of GAGs covalently linked to a core protein form proteoglycans

Question 18

Proteoglycans are strongly hydrophilic (T/F)

Answer 18

True

Form porous hydrated gel fills the extracellular space

Question 19

Proteoglycans

1. Form gels of varying ____ size that act as filters to regulate the passage of molecules through the extracellular matrix
2. They bind secreted _______ ________ and other proteins that serve as signals to the cells
3. They can block, encourage or guide ____ ________ through the extracellular matrix.

Answer 19

Proteoglycans

1. Form gels of varying pore size that act as filters to regulate the passage of molecules through the extracellular matrix
2. They bind secreted growth factors and other proteins that serve as signals to the cells
3. They can block, encourage or guide cell migration through the extracellular matrix.

Question 20

Fibronectin

• High-molecular-weight ________
• Contains binding sites for ________ and _______
• Binding sites for receptors on the cell surface
• Influence the potential of a cell for growth, differentiation, and migration
• Binds to membrane-spanning receptor proteins called _______

Answer 20

Fibronectin

• High-molecular-weight Glycoprotein
• Contains binding sites for Proteoglycans and Collagens
• Binding sites for receptors on the cell surface
• Influence the potential of a cell for growth, differentiation, and migration
• Binds to membrane-spanning receptor proteins called Intergrins

Question 21

Answer 21

Question 22

Answer 22

Question 23

Answer 23

Question 24

Clinical application of this glycoproteins has been found to aid wound healing. Deposited at wound interface after injury promotes cell migration

Answer 24

Fibronectin

Question 25

Family of integral membrane proteins composed of two membrane spanning polypeptide chains, (alpha and beta)

Answer 25

Integrins

Question 26

Main receptor proteins that cells use to both bind to and respond to the extracellular matrix?

Answer 26

Integrins ## Footnote *Integrins are involved in the adhesion of cells to substratum or other cells and transmission of signals from the external environment to the cell interior (“outside-in” signaling)*

Question 27

Extracellular glycoprotein that binds to cell surface receptors including proteoglycans, other components of the basal lamina, integrins and other instances of itself.

Answer 27

Laminin

Question 28

Two main classes of extracellular macromolecules that make up the matrix

Answer 28

(1) _glycosaminoglycans_(GAGs) * found covalently linked to protein in the form of proteoglycans (2) _fibrous proteins_ * collagen, elastin, fibronectin, and laminin * have both structural and adhesive functions

Question 29

* Focal Adhesions and Hemi-desmosomes are examples of \_\_\_\_\_\_\_\_\_ * What purpose do they serve

Answer 29

* Focal Adhesions and Hemi-desmosomes are examples of _Achoring Junctions_ * *Essential for providing* * *Tissue structure* * *Mechanical strain* * *Migration* * *Regulation of matrix expression* * *Wound healing*

Question 30

Hemi-Desmosomes: * Crucial for _______ structures * Connects intracellular intermediate filament network to extracellular matrix * ________ than focal adhesion * Transmembrane adhesion protein is an _______ rather than cadherin

Answer 30

Hemi-Desmosomes: * Crucial for _epithelial_ structures * Connects intracellular intermediate filament network to extracellular matrix * _Stronger_ than focal adhesion * Transmembrane adhesion protein is an _Integrin_ rather than cadherin

Question 31

Cadherin: Cell to \_\_\_\_\_\_ Integrin: Cell to\_\_\_\_\_\_

Answer 31

Cadherin: Cell to _Cell_ Integrin: Cell to _Matrix_

Question 32

\_\_\_\_\_\_\_\_\_ anchor the keratin filaments in an epithelial cell to the basal lamina

Answer 32

_Hemidesmosomes_ anchor the keratin filaments in an epithelial cell to the basal lamina

Question 33

Integrins link to keratin via \_\_\_\_\_\_

Answer 33

Integrins link to keratin via _plectin_

Question 34

Hemidesmosomes connect the basal surface of an epithelial cell to the underlying _____ \_\_\_\_\_ * The extracellular domains of the integrins that mediate the adhesion bind to a ______ protein in the basal lamina * An intracellular domain binds via an anchor protein (\_\_\_\_\_\_\_) to keratin intermediate filaments.

Answer 34

Hemidesmosomes connect the basal surface of an epithelial cell to the underlying _Basal Lamina_ * The extracellular domains of the integrins that mediate the adhesion bind to a _Laminin_ protein in the basal lamina * An intracellular domain binds via an anchor protein (_Plectin_) to keratin intermediate filaments.

Question 35

## Footnote Plasma membrane in scattered regions of _______ \_\_\_\_\_\_\_\_ contains large clusters of integrins Dynamic structures –can be rapidly disassembled

Answer 35

Plasma membrane in scattered regions of _focal adhesion_ contains large clusters of integrins Dynamic structures –can be rapidly disassembled

Question 36

\_\_\_\_\_\_\_ _______ can be assembled and disassembled to facilitate cell movement via actin and myosin filaments

Answer 36

_Focal adhesions_ can be assembled and disassembled to facilitate cell movement via actin and myosin filaments

Question 37

\_\_\_\_\_\_\_ on white blood cells help cells to crawl out of blood vessels at sites of infection, Lack of this type of protein leads to _______ \_\_\_\_\_\_\_ ________ and susceptibility to infection

Answer 37

_Integrins_ on white blood cells help cells to crawl out of blood vessels at sites of infection, Lack of this type of integrin leads to _leukocyte adhesion deficiency_ and susceptibility to infection

Question 38

Individuals who lack a certain type of ______ bleed excessively as their platelets cannot bind to the necessary clotting factor in the extracellular matrix

Answer 38

Individuals who lack a certain type of _Integrin_ bleed excessively as their platelets cannot bind to the necessary clotting factor in the extracellular matrix

Question 39

Extracellular Matrix * The extracellular matrix consists of secreted _________ ie. collagen * Collagen is embedded in a network of ________ fibers * Cells are attached to ECM by _______ which binds to Integrins which are transmembrane.

Answer 39

Extracellular Matrix * The extracellular matrix consists of secreted _glycoproteins_ ie. collagen * Collagen is embedded in a network of _proteoglycan_ fibers * Cells are attached to ECM by _Fibronectrin_ which binds to Integrins which are transmembrane.

Question 40

* Fibronectin binds to transmembrane Integrins allowing signaling from \_\_\_\_\_\_\_ * Integrins bind to actin filaments allowing signaling from the \_\_\_\_\_\_\_

Answer 40

* Fibronectin binds to transmembrane Integrins allowing signaling from _Outside- In_ * Integrins bind to actin filaments allowing signaling from the _Inside-Out_

Question 41

\_\_\_\_\_\_\_\_\_\_\_: - Cell-cell fusion, barrier function, dynamic - Occludin, Claudin

Answer 41

_Tight Junction_: - Cell-cell fusion, barrier function, dynamic - Occludin, Claudin

Question 42

\_\_\_\_\_\_\_\_\_\_\_\_\_\_: - Cell-cell fusion, senses contact, dynamic. - cadherins, catenins, vinculin, cortical actin

Answer 42

_Adherens Junction_: - Cell-cell fusion, senses contact, dynamic. - cadherins, catenins, vinculin, cortical actin

Question 43

\_\_\_\_\_\_\_\_\_\_\_\_\_\_: - Fastening cells, Rivet. - Connected to intermediate filaments. - cadherin, plakoglobin/desmoplakin

Answer 43

_Desmosome_: - Fastening cells, Rivet. - Connected to intermediate filaments. - cadherin, plakoglobin/desmoplakin

Question 44

\_\_\_\_\_\_\_\_\_\_\_\_\_\_: - Cytoplasmic channels between cells. - Connexins - Transfer of nutrients and genetic material.

Answer 44

_Gap Junctions_: - Cytoplasmic channels between cells. - Connexins - Transfer of nutrients and genetic material.

Question 45

\_\_\_\_\_\_\_\_\_\_\_\_\_: - attachment to the basal lamina (laminin) - integrin, plectin, keratin

Answer 45

_Hemi Desmosome_: - attachment to the basal lamina (laminin) - integrin, plectin, keratin

Question 46

\_\_\_\_\_\_\_\_\_\_\_\_\_: - Fibroblast to ECM (fibronectin) - motility - signaling - matrix synthesis - integrin, talin, filamin, vinculin, actin

Answer 46

_Focal Adhesions_: - Fibroblast to ECM (fibronectin) - motility - signaling - matrix synthesis - integrin, talin, filamin, vinculin, actin