Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Proteins > Collagen > Flashcards

Collagen Flashcards

(65 cards)

Start Studying
1
Q

What type of protein is collagen?

What type of fibres does it form?

A

It is part of a family of fibrous proteins

It forms insoluble fibres and has a high tensile strength

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

What is collagen a major element of?

What organs is it found in?

A

It is present in most organs

It is a major element of skin, bone, tendon, cartilage, blood vessels and teeth

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

How does collagen hold cells together?

What is its role in developing tissues?

A

It holds cells together in discrete units called basement membranes

It has a directive role in developing tissue

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

How abundant is collagen?

A

it is the most abundant protein in mammals

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

How many different types of collagen are there?

Why are there different types of collagen?

A

There are 12 different types of collagen

The different types result from different polypeptide chains in tropocollagen

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

What are the 3 broad types of collagen?

A
  1. fibril-forming collagens
  2. network-forming collagens
  3. fibril-associated collagens
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the fibril-forming collagens?

Where are they found?

A

Types I, II and III

They form long fibrils

They are involved in bone and tendon

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

What are the network-forming collagens?

What structure do they form?

A

Types IV and VII

They DO NOT form long protein ropes, they form a 2 dimensional matrix

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

What is the importance of the matrix formed by network-forming collagens?

A

It is important in the basal lamina

This ensures that tissues are properly organised

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

What are the fibril-associated collagens?

What are they involved with?

A

Types V, IX and XII

They are involved in crosslinking between other collagen molecules

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

How many protein chains does each type of collagen consist of?

A

All types of collagen consist of 3 protein chains

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

What happens to a newly synthesised polypeptide within fibroblast cells?

A

There are 3 main modifications that make the pre-pro-polypeptide into a pro-collagen molecule

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

What is the first modification that a pre-pro-polypeptide must undergo within fibroblast cells?

A

The signal peptide from the N-terminal is removed

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

What additional residues are added to the pre-pro-polypeptide in fibroblast cells?

What enzyme is involved?

A

Lysine and proline residues get additional hydroxyl groups added to them

This is catalysed by hydroxylase enzymes, which require vitamin C as a cofactor

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

What happens after the lysine and proline residues have had hydroxyl groups added to them?

A

Glycosylation of the selected hydroxyl groups on lysine with galactose and b-glucose

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

What forms the procollagen triple helical cable?

A

3 left handed helices twisting into a right-handed coil

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

What happens to the procollagen after it is formed?

A

It moves into the Golgi apparatus for final modifications

It is then packaged into secretory vesicles to enter the extracellular space

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

What enzymes act on the procollagen in the extracellular spaces of connective tissue?

What do they do?

A

Collagen peptidases perform propeptide cleavage

They remove the ends of the procollagen molecule so that it becomes tropocollagen

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

What happens to tropocollagen molecules after they have formed?

A

They aggregate to form a fibril

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

What enzyme acts on tropocollagen molecules within an aggregated fibril?

What does it do?

A

Lysyl oxidase enzyme acts on lysine and hydroxylysines

This causes covalent bonds to form between tropocollagen molecules in the fibril

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

What is the primary structure of collagen like?

A

Collagen has a repeating unit where glycine is every third residue

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

What is the typical repeating unit in collagen?

A

(Gly - X - Y)

Where X is often Pro and Y is often Hyp

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

What are the 3 different covalently modified amino acids found in collagen?

A

4-hydroxylproline (Hyp)

5-hydroxyllysine (HyL)

Allysine

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

How is allysine formed?

A

From the deamination of lysine or hydroxylysine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What enzymes catalyse hydroxylation of proline and lysine residues? When does this occur?
Prolyl hydroxylase and lysyl hydroxylase They BOTH require vitamin C as a cofactor This process occurs before the polypeptide chains form a helix
26
What is hydroxyproline involved with?
Hydrogen bond formation This helps to stabilise the triple helix
27
What is hydroxylysine involved with?
The residues are attachment sites for sugar residues They are also involved in cross-linking between collagen chains
28
What is the secondary structure of collagen?
Each polypeptide chain forms a left-handed helix with 3.3 residues per turn
29
Why is the secondary structure of collagen different to an alpha helix?
1. alpha helix has a right-handed configuration | 2. the alpha helix is NOT as tightly wound
30
What is the quaternary structure of collagen? What does it form?
Right-handed triple helix formed from 3 polypeptide chains twisted together This triple-helical cable is tropocollagen
31
How does the arrangement of side chains in tropocollagen differ to an alpha helix?
In an alpha helix, all the side chains sit outside the helix In tropocollagen, the glycine residues are packed into the centre of the molecule
32
What are extension peptides?
Collagen chains are synthesised with additional amino acids at each end These are extension peptides
33
What is the first stage in assembly of collagen?
Disulphide bonds form between the C-terminal extensions This pins the 3 strands together and holds them in place during triple helix formation
34
How come disulphide bonds can form between C-terminal extensions?
Cysteine residues have free -SH groups that can form disulphide bonds
35
What happens after disulphide bonds have formed in collagen assembly?
The triple helix is secreted into the extracellular space Peptidase enzymes cleave off the extension peptides
36
What happens once the extension peptides have been cleaved off?
Tropocollagen spontaneously forms fibrils They are stabilised by covalent cross-links between the strands
37
What is the purpose of covalent cross-links between and within tropocollagen molecules?
They give tropocollagen strength and rigidity
38
Between which residues can cross-links form?
Between lysine and allysine Or between 2 allysine residues
39
What makes up a collagen microfibril?
A collagen microfibril consists of a staggered array of tropocollagen molecules The tropocollagen molecules are held together by cross-links
40
What are nucleation sites? What happens there?
Holes between tropocollagen fibrils Calcium deposition occurs at the nucleation sites to form bone
41
How are nucleation sites positioned and why?
They are evenly positioned along the fibre to give an even deposition of collagen This produces strong bones
42
What is formed from large groups of collagen fibrils?
A larger fibre The fibres are then incorporated into a primary fibre bundle
43
What is the endotendon?
The membrane that surrounds each primary fibre bundle This holds separate units together and increases the strength of the tendon
44
What is the entire tendon structure surrounded by?
A membrane - the epitendon membrane
45
What is the turnover rate of collagen like?
It is very stable and does not have a high turnover rate under normal conditions
46
When may collagen breakdown be necessary?
Tissue repair Growth Tissue remodelling (e.g. pregnancy)
47
What enzymes catalyse the break down of collagen?
Collagenases
48
What family of enzymes do collagenases come from?
Metalloproteinases These are enzymes which break down protein and have a metal ion in their active site
49
Why are collagenases important in cancerous tumour formation and metastasis?
In order for a tumour to spread, it must penetrate the basement membrane Tumours secrete collagenases to achieve this
50
What causes Dupuytren's contracture?
excess collagen production
51
What does Dupuytren's contracture affect?
It affects the connective tissue in the hand, causing the fingers to bend and become stiff
52
How is Dupuytren's contracture treated?
Injection of collagenases
53
What causes Ehlers-Danlos syndrome?
A range of different mutations in the collagen chain It is often a missing or ineffective lysyl oxidase enzyme It is an inherited disorder
54
What is the consequence of having a missing or ineffective lysyl oxidase enzyme?
No covalent crosslinks can form to stabilise the final collagen molecule
55
What are the consequences of Ehlers-Danlos syndrome?
It leads to fragile stretchy skin and hyperextendable joints The specific symptoms vary depending on the mutation that causes the disease
56
What are the consequences of having hyperextendable joints?
1. frequent dislocations 2. joints coming out of place without prior injury 3. problems with blood vessels 4. problems with eyesight
57
What causes osteogenesis imperfecta (brittle bone disease)? What is it?
Mutations in type I collagen It is a range of inherited disorders leading to an increase in the risk of bone fractures
58
Why is osteogenesis imperfecta often difficult to diagnose?
It often arises as a spontaneous mutation This means there is no family history to suggest a genetic disorder
59
What commonly causes osteogenesis imperfecta? How does this impact collagen?
Mutation of a glycine residue Replacing a glycine residue with an AA with a large side chain affects formation of the triple helix
60
What is characteristic of Type I osteogenesis imperfecta?
It is the least severe It is shown by curvature of the bones
61
Why is there no such thing as type II osteogenesis imperfecta?
Babies with this type do not survive birth
62
What is characteristic of type III osteogenesis imperfecta?
Severe bone damage and curvature of the spine and long bones Bones are weak and any weight put on them causes them to break Height is restricted
63
What is characteristic of type IV osteogenesis imperfecta?
It often results in amputations This is because the bones are so damaged that they cause too much pain
64
What is significant about type III and IV osteogenesis imperfecta?
Sufferers are almost always in wheelchairs
65
What treatment may be used for milder cases of brittle bone disease?
Steel rods may be inserted into the bones of sufferers to aid them in walking

Proteins (5 decks)

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