Brainscape's Knowledge GenomeTM

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


See full index

Molecular Biology > Adhesion of Cells and the Extracellular Matrix > Flashcards

Adhesion of Cells and the Extracellular Matrix Flashcards

1
Q

What are the components of connective tissue?

A
  • Cells (scattered)
  • Extracellular matrix
    • Fibrillar proteins
    • Hydrated gel of GAGs
      • The majority of GAGs are linked to specific proteins to make proteoglycans.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Which cells are found in connective tissue?

A
  • Fibroblasts
  • Myofibroblasts
  • Blood derived cells
    • Mast cells
    • Plasma cells
    • Macrophages
  • Chondroblasts - cartilage
  • Osteoblasts - bone
  • Adipocytes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the components of the connective tissue extracellular matrix?

A
  • Fibrillar proteins
    • Collagen - strength
    • Elastin - stretch
    • Fibronectin - enables networking
    • Laminin - enables networking
  • Polysaccharides glycosaminoglycans (GAGs) (in proteoglycans)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Describe the structure and function of fibroblasts.

A
  • Large cell (because it carries out protein synthesis).
  • Long extensions.
  • Synthesises and secretes collagen, elastin and proteoglycans.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Decribe the production of collagen.

A
  • Starts with a procollagen molecule in the RER.
  • Hydroxylation of proline and lysine residues in the RER.
  • Then, glycosylation of the molecule which adds either galactose or glucose to some lysine residues.
  • Once this happens, the molecule becomes a triple helix.
  • Then, this procollagen is secreted into the golgi, then into the EC matrix.
  • Once procollagen is in the ECM, enzymes called procollagen peptidases cleave the terminal ends of the procollagen.
  • Once it has cleaved the ends at the N and C terminal, the molecule is tropocollagen (highly insoluble).
  • Tropocollagen molecules can aggregate to form collagen fibrils.
  • Tropocollagen molecules become reinforced by hydroxy-lysine cross-links between molecules when 2 are in close contact.
    • These cross links are formed by the lysyl oxidase enzyme.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the structure of a collagen fibril.

A

Many staggered collagen molecules that are linked by the lysine hydroxylysine cross links which are formed by the lysyl oxidase enzyme.

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

How is collagen packaged in the RER?

A

Collagen is packaged into specialised (large) vesicles.

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

Where and how does collagen secretion occur?

A

Collagen secretion occurs by exocytosis at specialised sites.

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

Where are collagen fibrils produced and how are they organised?

A
  • In a membrane tube called a fibripositor.
  • Cells organise the collagen fibrils they secrete into fibres.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe the components of elastin.

A
  • Fibrous protein secreted by fibroblasts and other cells.
  • Elastin likes to exclude water.
    • Hydrophobic effect is the main driving force for recoil.
  • Made in fibroblasts and also smooth muscle cells and chondroblasts.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are proteoglycans?

A

Assemblages of glycosaminoglycans and proteins.

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

What is the function of proteoglycans?

A
  • Provide:
    • Matrix support / cushioning / hydration
    • Glue-like function
    • Links between protein of the ECM and cell surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe GAGs

A
  • Long chains of repeating disaccharide units
  • Highly charged (negative) and highly hydrated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe how the extracellular matrix is linked to the intracellular cytoskeleton.

A
  • Collagen / proteoglycans bind fibronectin that links to integrins which themselves bind via adaptors to the actin cytoskeleton.
  • Fibronectin acts as an adaptor protein on the outside.
  • Integrins bridge the membrane.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the structure and function of a myofibroblast.

A
  • Bi-functional
    • ​Fibroblast-like
      • Secrete collagen
    • Smooth muscle-like
      • Synthesise actin, myosin and desmin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the involvement of myofibroblasts following tissue damage.

A
  • Proliferate.
  • Secrete collagen (scaffold).
  • Consolidate damaged area (fibrous scar).
  • Contract (reduce size of damaged area; express focal adhesions and smooth muscle actin).
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How are myofibroblasts formed and why are they important?

A

They differentiate from fibroblasts under mechanical tension - especially important in wound healing. Also active in tissue fibrosis eg. liver cirrhosis.

18
Q

Which type of cell is shown?

A

Mast cell (granules contain heparin and histamine).

19
Q

Which type of cell is shown?

A

Plasma cell (antibody production is through the secretory pathway).

20
Q

Which type of cell is shown?

A

Macrophage (ingesting listeria bacteria / paramecium).

21
Q

What are the functions of adipocytes?

A
  • Insulation (subcutaneous)
  • Packing (eg. the eye)
  • Energy storage
22
Q

Describe the structure of an adipocyte.

A
  • Peripheral cytoplasm
  • Nucleus in the periphery
23
Q

What is leptin responsible for?

A

The satiety signal

24
Q

What is the function of cell junctions?

A
  • Cell junctions / adhesion proteins link cells an their cytoskeleton to:
    • Other cells
    • And to the extracellular matrix
25
Q

What are the 4 types of cell junction?

A
  • Tight junction
  • Adhesion belt
  • Desmosome
  • Gap junction
26
Q

What are the different types of cell-cell adhesion?

A
  • Integrin
  • Selectin
  • CAM
  • Focal adhesion
  • Hemi-desmosome
  • Membrane proteoglycan
27
Q

What are the functions of tight junctions?

A
  • Define polarity (fence-off membrane lipids and proteins).
  • Control the passage of substances between cells.
  • Can link to actin cytoskeleton.
28
Q

Describe adherens junctions.

A
  • Plaque anchors actin filaments at the membrane (not intermediate filaments).
  • Not as dense as desmosomes.
29
Q

Distinct cadherins provide cell adhesion in different tissues.

Give examples of this.

A
  • E-cadherin - epithelia
  • N-cadherin - neurons and heart muscle
  • P-cadherins - placenta and epidermis
  • VE-cadherin - endothelial cells
30
Q

Decribe desmosomes.

A
  • Link between strong intermediate filaments in adjacent cells.
  • Desmosomes are for strength.
  • Found in the skin.
31
Q

Describe the plaque and the filaments of desmosomes.

A
  • Plaque
    • ​Cytoplasmic dense plaque containing desmoplakin and plakoglobin proteins.
  • Filaments
    • ​Keratin filaments (tonofilaments) anchored to the cytoplasmic dense plaque.
32
Q

Describe gap juctions.

A
  • For communication
  • Hydrophilic channel
  • Small molecules pass
  • Coordination of function (important in the heart muscle).
33
Q

Describe focal adhesions.

A
  • Focal adhesions link the outside of the cell (ECM) through transmembrane proteins (integrins) with the cytoskeleton (actin filaments).
  • Dynamic (eg. in fibroblasts).
  • Also act as signalling platforms.
  • Link to fibronectin.
34
Q

Describe hemidesmosomes.

A
  • Hemidesmosomes link the outside of the cell (ECM) through transmembrane proteins (inegrins) with cytoskeleton (intermediate filaments).
  • More stable (eg. linking epithelial cells to the basement membrane).
  • Link laminin in the basement membrane.
35
Q

What are integrins?

A

A large family of proteins which bridges between cytosol and the ECM.

36
Q

Describe the molecular defect in Duchenne Muscular Dystrophy and how this leads to muscle dysfunction.

A
  • Gene mutation - absence of dystrophin (adaptor) due to premature termination of translocation.
  • Causes:
    • Damage to mucle fibres due to muscle tearing
    • Muscle wasting
    • Muscle weakness
    • Unable to walk by 12 years
37
Q

Outline the recent experimental approach to correct the defect associated with DMD.

A
  • PTC 124 (ataluren) is an experimental drug.
  • It is thought to override the premature stop signal mutation to produce normal dystrophin.
  • It also sems to work in the defective cystic fibrosis gene.
  • Findings:
    • Increasing doses of ataluren includes increased retention of dystrophin.
  • NICE approves ataluren for treatment of DMD.
38
Q

Describe the role of cell adhesion in cancer progression.

A
  • Tumour cells accumulate (mutations disregulated cell cycle).
  • Cells have not breached the basement membrane.
  • Carcinoma is in situ.
  • Cells undergo epithelial to mesenchymal transition (EMT).
39
Q

Describe microinvasion of cell adhesion molecules in cancer.

A
  • Cells convert to ‘mesenchymal’ cells and expression of cadherins is reduced.
  • Microinvasion starts aided by actin-based protrusions called invadopodia.
  • Secretion of metalloproteases (MMPs).
  • Basement membrane breached.
  • In invading tumours leading cells express inegrins promoting interaction with ECM and non-epithelial cells during movement.
40
Q

Describe the role of cell adhesion in cancer when progression of metastasis occurs.

A
  • Autocrine motility factors from tumour (increases motility of tumour cells and decreases E-cadherin).
  • Angiogenesis factors (promote vascularisation).
  • Entry into and through lymphatics and blood vessels.
  • Dissemination - metastasis.

Molecular Biology (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions