Brainscape's Knowledge GenomeTM

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


See full index

Molecular Biology of The Cell - POM > Extracellular matrix > Flashcards

Extracellular matrix Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Biology flashcards Biology 101 flashcards
1
Q

What is the ECM and what is it made up of

A

The extracellular matrix is the connective tissue that makes up the space between cells and consists of carbohydrates and proteins with fibrillar and non-fibrillar components

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

What role does ECM play in tissues

A

The extracellular matrix provides physical support to cells in a tissue, determines the physical and chemical properties of a tissue, it influences cell growth, differentiation and adhesion, it is required for development and organogenesis

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

What does connective tissue consist of

A

Connective tissue consists of collagen, fibroblasts secreting ECM such as glycosaminoglycans, often also contain capillaries and mast cells

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

Which cells synthesise substances of ECM

A

Fibroblasts synthesise the substances of the ECM, such as collagen, glycosaminoglycans, proteoglycans and glycoproteins

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

What are the three major molecular components of connective tissues

A

Collagens, multi-adhesive glycoproteins and proteoglycans are the main molecular components of connective tissues and the ECM

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the basement membrane

A

The basement membrane is a layer of extracellular matrix that is found under epithelial layer and divides the epithelium and the connective tissue or other tissues =

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

What are the major components of basal lamina

A

Collagen type IV, laminins and perlecan

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

Where are basement membranes found in human body

A

Basement membranes surround muscles, peripheral nerve and adipose tissues and underlie most epithelia

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

What is basement tissue for filtration in kidney called

A

Glomerular basement membrane (GBM)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens to the glomerular basement membrane in diabetic nephropathy

A

In diabetic nephropathy, there is an accumulation of extracellular matrix in the glomerular basement membrane which leads to thickening that inhibits renal filtration and leads to renal failure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens to the glomerular basement membrane in Alpert syndrome and what are other symptoms

A

In Alpert syndrome there is a genetic mutation in type IV collagen, which leads to abnormal glomerular basement membrane and progressive loss of kidney function and also hearing loss

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

What are elastic fibres made up of and where are they found in body

A

Elastic fibres are made up of a core of elastin and microfibrils surrounding it made up of fibrillin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the function of fibrillin

A

Fibrillin forms microfibrils that maintain the integrity of the elastic fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is Marfan’s syndrome and what are its manifestations

A

In Marfan’s syndrome there is a mutation in fibrillin which leads to loss of elastic fibre integrity and manifests in skeletal system as arachnodactyly and cardiovascular system with high risk of aortic rupture and ocular problems

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is elastin protein made up of and how can it stretch

A

The elastin protein is made up of two segments; alternating hydrophobic regions and a-helices containing lysine and alanine. The crosslinked elastin proteins are coiled and when the elastic fibre is stretch, they uncoil and form straight protein chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How are elastin proteins crosslinked in elastic fibre

A

The lysine residues in a-helix regions of the elastin crosslinks with other elastin polypeptides to form a network

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Where are collagens found and how much of collagen in mammals

A

Collagens are found in bone, tendon, skin, connective tissue and 25% of protein mass of mammals consists of collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does collagen arrangement resist tensile force

A

When collagen fibres are directed in different directions, it can resist force in all different directions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Which tissues contain layers of perpendicular collagen

A

The skin, mature bone, cornea, all tissues that must resist tensile force contain perpendicular successive layers of collagen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

How many chains does collages consist of and what is the characteristic repetition

A

Collagen consists of three alpha chains that form a triple helix, and the chains have a repetion of glycine-x-y where x often is proline and y hydroxyproline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What classifies different collagen types

A

The different combination of alpha chains in the triple helix defines which type a collagen is

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

In characteristic repetition in collagens, what is x and y often

A

The characteristic repetition in collagen often consists of glycine then proline as x and hydroxyproline as y

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Why does characteristic repeat contain glycine

A

Glycine is an amino acid with a small residue that can point inwards and hold the chains in the helix together

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

How long are alpha chains in fibrillar collagens approximately

A

Alpha chains in fibrillar collagens consist of approximately 1000 amino acids

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How is triple chain collagen molecule organised in connective tissue

A

The collagen helixes form bundles called collagen fibrils that form bundles called collagen fibres

26
Q

What is difference between collagen inside and outside of cell

A

Newly synthesised collagen chains contain non-collagenous N- and C-domains in intracellular collagen that have to be cleaved from the protein to form the extracellular collagen

27
Q

How can extracellular collagen be synthesised from procollagen

A

The non-collagenous N- and C-domains have to be removed when procollagen is transport out of the cell to form collagen

28
Q

How is the tensile strength and stability of the fibril increased

A

By cross-linking the collagen triple helixes, the tensile strength and stability of the collagen fibril and fibre are increased

29
Q

What amino acid residues are involved in cross-linking of the collagen

A

Lysine and post-translationally modified hydroxylysine are involved in cross-linking between collagen triplets

30
Q

How does type and extent of crosslinking relate to tissue function and age

A

The amount of cross-linking relates to the forces the tissue must endure and with ages these cross-links tend to decrease in numbers and become less regularly patterned

31
Q

What are the 9 steps of biosynthesis of fibrillar collagen

A
  1. The synthesis of pro-a-chains, 2. the hydroxylation of selected lysine and proline residues, 3. the glycosylation of a-chains, 4. the self-assembly of the pro-a-chains, 5. triple helix formation of three pro-a-chains, 6. secretion of procollagen, 7. the cleavage of non-collagenous N- and C-domains, 8. self-assembly into fibrils and crosslinking, 9. aggregation of fibrils into fibres
32
Q

What residues are needed for formation of cross-links and what does this require

A

Lysine and hydroxylysine residues in the collagen proteins are required for cross-linking, this requires lysyl oxidases which crosslinks hydroxylysine and lysine together

33
Q

What can a vitamin-C deficiency result in relating to collagen

A

Vitamin-C deficiency can lead to inhibition of hydroxylation of collagen and this underhydroxylation can lead to loss of collagen stability and tissue stability and this is scurvy

34
Q

What are Ehlers-Danlos syndromes and what is their cause

A

Ehler-Danlos syndromes are a group of genetic disorders that cause stretchy skin and loose joints, caused by mutations in collagen that affect collagen production, structure or processing

35
Q

What do collagen types IX to XII do and what is this type of collagen called

A

Collagen type IX to XII are called fibril-associated collagen and associate with collagen fibrils to regulate their organisation

36
Q

What is type IV collagen, where is it found and what is this type of collagen called

A

Type IV collagen is a network-forming collagen, found in all basement membranes but constitution can vary from tissue to tissue

37
Q

How does type IV collagen form networks and what is different in secondary structure to fibrillar collagens

A

In type IV collagen, the uncleaved N- and C-terminals interact to connect monomer chains to form a network in a mesh-like structure. In fibrillar collagens, the N- and C-terminals are cleaved.

38
Q

What is the function of the hydroxylation of lysine and proline residues in collagen fibrils

A

The hydroxylysine and hydroxyproline can form hydrogen bonds between collagen triplets and this can increase the strength of the collagen fibrils and fibres

39
Q

What do the modular protein domains in extracellular matrix proteins do

A

The modular domains can make it possible for a protein to bind to many different structures in the extracellular matrix and cell-surface receptors

40
Q

What do laminins consist of and what shape do they adopt

A

Laminins are heteromeric proteins consisting of an alpha-, beta- and gamma-chain that adopts a form of a cross

41
Q

What can multi-adhesive laminins bind to in basement membrane and other ECM

A

Multi-adhesive laminins can self-associate in the basement membrane, but can also bind to integrins, collagen type IV and nidogen and to cell-surface receptors like integrins and dystrogen

42
Q

What is congenital muscular dystrophy caused by and what are its symptoms

A

In congenital muscular dystrophy there are mutations in the alpha-chain of laminin and this causes symptoms like hypotonia, general weakness and deformities of joints

43
Q

What regions does fibronectin consist of and how is the dimer connected

A

Fibronectin consists of a two large modular protein with collagen, integrin and heparin binding domains which are connected by disulphide bonds

44
Q

Where can fibrinectins be found and in what two forms do they exist

A

Fibronectins can be found in extracellular matrix or in body fluids, either as insoluble fibrillar matrix or as soluble plasma protein

45
Q

How are different fibronectin types formed

A

All fibronectins are formed from one encoding gene, which can be spliced differently to produce different forms of fibronectin

46
Q

In what processes play fibronectin important roles

A

In cell adhesion and migration, particularly in embryogenesis and wound repair, and in blood clotting

47
Q

How do fibronectin and actin form a mechanical continuum and what is its function

A

Fibronectin is bound to integrins which are bound to actin and hence it forms an attachment point for the cell to the extracellular matrix at the sites where it is enforced by the actin cytoskeleton

48
Q

What do proteoglycans consist of

A

Proteoglycans consist of a core protein which one or many more glycosaminoglycans (GAGs) attached

49
Q

What do GAGs consist of and why do they often carry charge

A

Glycosaminoglycan chains consist of disaccharide repetitive units of which one or two are amino sugars. They often carry negative charge because they often contain sulfate or carboxyl groups

50
Q

What are the four principal proteoglycan families

A

Basement membrane proteoglycans, aggregating proteoglycans (that bind to hyaluronan), small leucine-rich proteoglycans, cell surface proteoglycans

51
Q

What are the four major GAG chains in human tissue

A

Hyaluronan, chondroiton sulfate and dermatan sulfate, heparan sulfate, keratan sulfate

52
Q

Where are GAGs synthesised and attached to core protein and what is the exception

A

GAGs and the core proteins are synthesised in the fibroblasts in the connective tissues, but hyaluronan is directly formed by an enzyme on the cell surface

53
Q

What kind of proteoglycan is perlecan

A

Perlecan is a basement membrane proteoglycan

54
Q

How many GAGs can proteoglycan possess

A

Proteoglycans can carry up to 100 GAGs per core protein

55
Q

What does hyaluronan consist of and where is it found

A

Hyaluronan is a long carbohydrate chain consisting of glucoronic acid and N-acetylglucosamine, which is found in the extracellular matrix of soft connective tissue

56
Q

Where is hyaluronan used for high viscosity

A

Hyaluronan is found in the vitreous humour of the eye and the synovial fluid of joints, where it protects the cartilage surface from damage

57
Q

What is special about hyaluronan polymerisation

A

It can reach enormous sizes of more than 10.000 disaccharides polymerised

58
Q

What does cartilage tissue consist of and how can it resist compressive force

A

The extracellular matrix in cartilage tissue is produced by chondroctyes and consists mainly of aggrecan, a highly sulfated and carboxylated proteoglycan that contracts cations such as sodium because it is so negatively charged. This makes it osmotically active and retain a lot of water. Under compressive force, this water is pressed out of the extracellular matrix and reabsorbed when the force is relieved. It also contains collagen and elastin.

59
Q

What does aggrecan consist of

A

Aggrecan consists of a core protein with a hyaluronan binding region and the GAGs chondroitin sulfate and keratan sulfate attached containing high negative charge

60
Q

What is osteoarthritis and what is the problem in function of cartilage

A

Over time, aggrecan in the cartilage is cleaved by aggrecanases and metalloproteinases that result in loss of aggrecan that can resist compressive force, which leads to damage of the cartilage layer and the bone layer below

61
Q

What causes fibrotic diseases

A

The excessive production of extracellular matrix in fibrous connective tissue, often after infection, causes fibrotic diseases

Molecular Biology of The Cell - POM (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions