Brainscape's Knowledge GenomeTM

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


See full index

Extracellular Matrix Ben > Connective Tissue > Flashcards

Connective Tissue Flashcards

1
Q

Connective tissue is made of the extracellular matrix and component cells. What are the main components in the extracellular matrix?

A

Collagens, multi-adhesive glycoproteins and proteoglycans.

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

How can connective tissue have a variety of different properties?

A

The different types and arrangement of collagen can give varied properties. The absence or presence of certain components can also add variety.

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

What is collagen and how abundant is it?

A

Collagen is a fibrous protein found in all multicellular organisms and is the most abundant protein in mammals, making up 25% of total protein mass.

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

How does collagen align itself in order to provide strength?

A

In skin, successive layers of collagen are at right angle to each other, allowing for compression and strength.

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

How many types of collagen are there?

A

28

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

How many genes encode for collagen in humans?

A

42

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

What is the structure of collagen?
(How do chains combine)
(Describe the chains)
(What also gives collagen strength)

A

Three alpha chains are arranged in a left handed triple helix. These chains can all be the same type (homotrimers) or can be different types (heterotrimers).

Each alpha chain is about 1000 amino acids long, and the triple helix forms a characteristic gly-x-y repeat, with X often being proline and Y often being hydroxyproline. Every third position must be glycine, which is also small enough to occupy the interior of the helix, the H side chain, which allows for very stiff packing of molecules.

Covalent cross linkages between collagen work intramolecularly.
The cross links provide tensile strength and stability. Some tissues require more than others and cross links become less regular as we age. The cross links involve both lysine and hydroxylysine residues.

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

How are collagen fibres assembled?

A

Three collagen polypeptide alpha chains combine to form a triple stranded collagen molecule.
These molecules then associate to form fibrils.
These fibrils come together to form fibres.

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

All newly synthesised collagen chains have what before being removed? When are they removed?

A

Non-collagenous domains at the N (NH2 part of the amino acid chain) and C (COOH part of the amino acid chain) termini. These only get removed if the collagen is going to leave the cell, otherwise they remain.

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

What are newly synthesised collagen molecules called?

A

Procollagen.

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

Where is collagen synthesised?

A

Cytoplasm and ER/Golgi

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

Prolyl and lysyl hydroxylases require what for interchain hydrogen bond formation?

A

Fe2+ and vitamin C

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

Lysine and hydroxylysine are also modified in the formation of covalent cross linkages. When do this occur?

A

This only occurs after the collagen has been secreted from the cell.

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

What will a vitamin C deficiency cause in terms of collagen?

A

Under hydroxylated collagen, with less hydrogen bonds. This will cause problems with tissue stability and strength.

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

What is EDS, what are it symptoms and what is it caused by?

A

EDS or Ehlers-Danos syndrome is a group of inherited connective tissue disorders whose symptoms include stretchy skin and loose joint.
Several disorders arise due to mutation in collagen, which negatively affect collagen production, structure and processing.

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

Do all collagen molecules form fibrils?

A

No, there are fibril associated collagens such as types IX and XII which associate with fibrillar collagens and regulate the organisation of collagen fibrils.

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

What is type IV collagen and what is special about its structure?

A

It is a network forming collagen and is present in all basements membranes, though it’s molecular constitution varies from tissue to tissue.
It’s N and C domains are not cleaved after secretion and they react through these to form a sheet like network. They self assemble from a monomer, to a dimer, to a tetramer until finally forming a supramolecular aggregate.

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

What are basement membranes also known as?

A

Basal laminae.

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

What are basement membranes?

A

Flexible thin mats of extracellular matrix underlying epithelial sheets and tubes.

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

What do basement membranes do in the kidneys?

A

They form a key part of the Glomerular Basement Membrane GBM

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

What happens to people with diabetic nephropathy?

A

There is an accumulation of extracellular matrix leading to a highly thickened basement membrane. This restricts renal filtration and can lead to renal failure.

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

What happens in Alport syndrome?

A

In Alport syndrome, mutations in collagen IV result in an abnormally split and laminated GBM which is associated with a progressive loss of kidney function and also hearing loss.

23
Q

What is responsible for the elasticity of tissues?

A

Elastic Fibres

24
Q

How is the extent of stretching due to elastic fibres limited?

A

Often, collagen and elastic fibres are interwoven to limit the extent of stretching.

25
Q

What are elastic fibres composed of?

A

Elastic fibres consist of a core made up of the protein elastin, and microfibrils, which are rich in the protein fibrillin.

26
Q

What do the fibrils due in elastic fibres?

A

Provide integrity and strength.

27
Q

What is Marfan’s Syndrome?

A

A condition due to mutations in the protein fibrillin-1, causing sufferers to be tall and thin with long and thin limbs, hypermobility as well as heart defects.

28
Q

What is the structure of elastin?

A

It consists of two segments that alternate along the polypeptide chain: hydrophobic regions, and α-helical regions rich in alanine and lysine. Many lysine side chains are covalently cross-linked.

29
Q

What is the multifunctionality of extracellular proteins a result of?

A

Their large, modular structure allowing them to bind various matrix components.

30
Q

What are laminins?

A

L​aminins are multi-adhesive proteins which can interact with a variety of cell surface receptors including integrins and dystroglycan. They can self-associate as part of the basement membrane matrix, but can also interact with other matrix components such as type IV collagen, nidogen and proteoglycans.

31
Q

What is the structure of laminins?

A

Laminins are heterotrimeric proteins made up of an α chain, a β chain and a γ chain, which form a cross shaped molecules. Laminins are very large proteins.

32
Q

Mutations in laminin chains are associated with what diseases?

A

Mutations in specific chains are associated with inherited diseases such as muscular dystrophy and epidermolysis bullosa.

33
Q

What can congenital muscular dystrophy be a result of?

A

Congenital muscular dystrophy can arise from an absence of the α2 chain in laminin 2.

34
Q

What are the symptoms of congenital muscular dystrophy?

A

Symptoms include hypotonia (abnormally decreased muscle tension), a generalised weakness and deformities of the joints.

35
Q

What do fibronectins do?

A

Fibronectins are able to interact with cell surface receptors and other matrix molecules. They play important roles in regulating cell adhesion and migration in a variety of processes, notably embryogenesis and tissue repair. They are also important for wound healing, helping to promote blood clotting.

36
Q

What links the matrix with the actin cytoskeleton of cells?

A

Integrin receptors at the cell surface provide the linkage between the matrix and the cytoskeleton.

37
Q

What are proteoglycans?

A

Proteoglycans are core proteins to which are covalently attached one or more glycosaminoglycan (GAG) chains.

38
Q

What are GAG chains made of?

A

GAG chains are made up of repeating disaccharide units with one of the two sugars being an amino sugar (a sugar in which a hydroxyl group is replaced with an amine group).

39
Q

How can GAG chains draw water in the ECM?

A

Many GAGs are sulfated or carboxylated, and as a result carry a high negative charge.
This charge attracts a cloud of cations including Na+, resulting in large amounts of water being sucked into the extracellular matrix.

40
Q

What are the four main types of proteoglycans?

A

Basement membrane proteoglycans
Aggregating proteoglycans (interact with hyaluronan)
Small leucine-rich proteoglycans
Cell surface proteoglycans

41
Q

How do GAGs contribute the tensile strength of cartilage?

A

Cartilage has a matrix rich in collagen with large quantities of GAGs trapped within the meshwork. The balance of swelling pressure is negated by the tension in the collagen fibres, generating great tensile strength.

42
Q

How many GAG chains can the core protein attach to?

A

Small proteoglycans can have a single GAG chain attached, whereas some large proteoglycans carry up to 100 GAG chains.

43
Q

How are GAG chains grouped?

A

Based on the repeating disaccharide unit.

44
Q

What are the four main GAGs?

A

Hyaluronan
Chondroitin sulfate/dermatan sulfate
Heparan sulfate
Keratan sulfate

45
Q

Where is hyaluronan (a.k.a hyaluronic acid) made and how is this different?

A

Hyaluronan is spun out directly from an enzyme embedded in the plasma membrane. All the other GAGs are synthesized and attached to their core proteins in the endoplasmic reticulum and Golgi apparatus inside the cells.

46
Q

Where is hyaluronan found?

A

Hyaluronan is found in the extracellular matrix of soft connective tissues.

47
Q

How is the structure of hyaluronan distinct from the other GAGs?

A

It is distinct from the other GAGs as it is simply a carbohydrate chain without a core protein.

48
Q

What is the structure of hyaluronan?

A

It is unsulfated and made up of repeating disaccharides which can number up to 25,000 sugars.
Hyaluronan can undergo a very high degree of polymerization, typically in the range of 10,000 disaccharides creating molecules of enormous sizes. This means that hyaluronan chains can occupy a relatively large volume.

49
Q

How viscous is hyaluronan?

A

Very viscous and so found in the vitreous humour of the eye and in the synovial fluid if the joint, playing a key role in protecting the cartilaginous surface from damage.

50
Q

What is aggrecan made of?

A

Highly sulfated GAG chains with large numbers of negatively charged carboxyl groups that attract cations such as Na+, making it very osmotically active and retaining lots of water.

51
Q

What does aggrecan’s osmotic properties allow?

A

Under compressive load, water is given up but regained once the load is reduced. Therefore, aggrecan in the cartilage matrix is perfectly suited to resist compressive forces.

52
Q

What is osteoarthritis?

A

Osteoarthritis is an erosive disease resulting in excessive extracellular matrix degradation.
The cushioning properties of cartilage over the end of bones are lost.

53
Q

What causes osteoarthritis?

A

With increasing age, aggrecan is cleaved by aggrecanases and metalloproteinases. This results in a loss of aggrecan fragments to the synovial fluid.

54
Q

What are fibrotic diseases a result of?

A

F​ibrotic diseases arise as a result of an excessive production of fibrous connective tissue.

Extracellular Matrix Ben (2 decks)

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