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Dermatology > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

What are the protein fibers embedded in within the ECM?

A

Ground substance

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2
Q

What are the 3 structural, fibrous proteins of the ECM?

A

Collagen
Elastin
Fibrillin

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3
Q

What are the 2 specialized proteins that link the structural, fibrous proteins to the surface of the cells?

A

Fibronectin and laminin

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4
Q

What are the molecules that comprise long chains of repeating disaccharides, GAGs, are attached to specific core proteins, and are the major component of ground substance?

A

Proteoglycans

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5
Q

What % of proteoglycans is proteins and GAGs?

A

5% protein

95% GAGs

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6
Q

What are the fibers that have a high tensile strength and comprise the most abundant form of protein in animals?

A

Collagen

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7
Q

What is the final assembly molecule of collagen called, where there is cross-linking of triple-helical rods?

A

Tropocollagen

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8
Q

Which cells secrete collagen?

A

Fibroblasts, osteoblasts, and chondroblasts.

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9
Q

What is the most abundant type of collagen?

A

Type I

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10
Q

What is the main collagen in basement membranes?

A

Type IV

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11
Q

In addition to the triple helical rod of tropocollagen, what does it have on the outsides of the triple helix to allow cross linking by both covalent and H-bonds to toughen the structure?

A

R-groups of AA
N-H
C=O

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12
Q

What is the fiber arrangement of collagen in tendon?

A

Parallel bundles

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13
Q

What is the fiber arrangement of collagen in Bone?

A

Angled to the axis of the bone to provide resistance to shear forces

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14
Q

What is the fiber arrangement of collagen in skin?

A

sheets of fibers at many angles

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15
Q

What is the fiber arrangement of collagen in cartilage?

A

No distinct arrangement

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16
Q

What is the fiber arrangement of collagen in the cornea?

A

Planar sheets stacked at right angles to each other to minimize light scatter

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17
Q

What molecule combines with fibrillin to confer elasticity of tissue?

A

Elastin

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18
Q

What cell makes elastin?

A

Fibroblasts

same as collagen

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19
Q

Unlike collagen, what is the secondary structure of elastin?

A

There is a lack of ordered 2o structure.

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20
Q

How many genes encode elastin?

A

1

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21
Q

Although elastin is made from 1 molecule, what process allows it to exist as several variants?

A

Differential mRNA processing

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22
Q

What is elastin synthesized and secreted as, which is converted to the monomer tropoelastin (70kD)?

A

Proelastin

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23
Q

Important: what 2 AA’s is elastin rich in, which collagen isnt rich in?

A

Pro

Lys

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24
Q

What molecule does lysine oxidase use to deaminate Lys to the corresponding aldehyde in elastin?

A

Cu++

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25
Q

What is a commonly occuring linkage in elastin?

A

3 Al-Lys and 1 Lys –> 4 separate tropelastin chains.

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26
Q

The cross-linked derivatives of Lys and stuff (desmosines) gives what characteristic of elastin?

A

Recoil!

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27
Q

What is the function of the single peptide on the preprocollagen in the RER?

A

Labels them for export

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28
Q

Where is the single peptide of the preprocollagen removed, which converts it to procollagen?

A

RER lumen

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29
Q

In addition to a-KG and O2, what molecule is needed to hydroxylate the Pro and Lys residues on procollagen?

A

Vitamin C

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30
Q

Prior to helix formation of procollagne, what 2 things are added to certain HO-LYS residues?

A

Glucose and Galactose

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31
Q

So the golgi secretes what form of collagen otuside of the cell?

A

Triple helix procollagen

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32
Q

What are removed from the triple helix procollagen to make tropocollagen?

A

Extension peptides

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33
Q

Which molecules are secreted by fibroblasts to act as a structural scaffold for the deposition of elastin?

A

Fibrillin

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34
Q

What is the major glycoprotein of the ECM?

A

Fibronectin

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35
Q

What is the major fxn of fibronectin?

A

Gluing cells together

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36
Q

What cells appear to be deficient in surface-boudn fibronectin?

A

Malignant cells

allows them to spread

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37
Q

Though malignant cells lack surface fibronectin, they have fibronectin receptors, which allows them to do what?

A

Metastasize

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38
Q

What is the role of fibronectin in pregnancy?

A

Attaches the amniotic sac to the lining of the uterus

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39
Q

Which test (from the cervical canal) suggest the patient is at risk for preterm labor?

A

Fetal fibronectin test

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40
Q

What is the large cruciform glycoprotein that is an essential component of the basal membrane?

A

Laminin

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41
Q

What is the main fxn of laminin?

A

Glues membrane to overlying cells

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42
Q

What happens if laminin is excessively broken down?

A

loss of growth control

43
Q

What is the inheritance of OI?

A

AD

44
Q

What happens to the eyes in OI?

A

Blue sclera

45
Q

What type of collagen is abnormal or reduced?

A

Type I collagen

46
Q

What type of OI is the most common and is the mildest?

A

Type I OI

47
Q

Which type of OI is the most severe, and is frequently lethal at or shortly after birth?

A

Type II OI

48
Q

Which one is worse: type III or type IV OI?

A

Type III

49
Q

What happens to type I collagen to cause type I OI?

A

Reduced production

50
Q

What types of mutations occur to cause type II, III, and IV OI?

A

Missense mutation

bulky AA’s in place of Gly –> destabilize the structure

51
Q

What is the inheritance of Ehlers-Danlos Syndrome (EDS)?

A

AD

52
Q

What are the main joint/skin Sx of EDS?

A

Hyperextensibility of skin

Hypermobility of joints

53
Q

Which form of EDS has a mutation in tenascin X and is the most common form?

A

Hypermobility form (III)

54
Q

Which form of EDS has a mutation in genes encoding type V collagen?

A

Classic form (I and II)

55
Q

Which form of EDS has a mutation in type III collagen, and is the most severe form?

A

Vascular form (IV)

56
Q

What is the inheritance of Alport syndrome?

A

AR or X-linked

57
Q

What is the main type of collagen affected in Alport syndrome?

A

Type IV collagen

basement membranes

58
Q

What are the main kidney manifestations of Alport syndrome?

A

Hematuria, proteinuria, kidney failure

59
Q

True or False: Alport syndrome is the 2nd most common cause of inherited kidney failure.

A

True

60
Q

In addition to kidney failure, Alport syndrome pts develop what other manifestation in early adulthood?

A

Deafness

61
Q

What is condition where there is a defect in type VII fibers, resulting in breakage and blistering of the skin?

A

Dystropic Epidermolysis Bullosa (DEB)

62
Q

What is the inheritance of DEB?

A

AD or AR

63
Q

What is the XR condition that is caused by mutations in copper-binding ATPase?

A

Menkes syndrome

64
Q

Again, which enzyme required Cu, which is decreased in Menkes syndrome because of lack of intestinal transport?

A

Lysine oxidase

65
Q

What are the main Sx to Menkes syndrome?

A

Kinky hair
Cerebral degeneration
Death in infancy

66
Q

Which disease results in defective hydroxylation of Lys and Pro, leading to bleeding gums, easy bleeding, painful joints, anemia, and the boundless desire to take over other ships?

A

Scurvy

67
Q

Though Williams syndrome can be AD, what is the most common cause?

A

Spontaneous mutation

68
Q

What is deleted from chromosome 7 to cause Williams syndrome?

A

ELN gene

encodes elastin

69
Q

What happens to the large arteries in Williams syndrome?

A

They narrow (no elastin)

70
Q

What is the main heart condition in Williams syndrome?

A

Supravalvular aortic stenosis (SVAS)

71
Q

What mythical creature do u look like in Williams syndrome?

A

Elf

72
Q

What are the neurological problems in Williams syndrome?

A

Overly-friendly

ADD

73
Q

True or False: SVAS is exclusive to Williams syndrome.

A

False

Smaller deletions of ELN can cause it without the Williams syndrome Sx, also in familial SVAS (AD)

74
Q

What is the inheritance of A1AT deficiency?

A

AR

75
Q

What is the normal function of A1AT?

A

Inhibits elastase (degrades elastin)

76
Q

Which cells produce elastase?

A

Neutrophils

77
Q

Which tissues are broken down in A1AT deficiency?

A

Alveoli

78
Q

What “act” exasterbates the emphysema seen in A1AT deficiency?

A

Smoking

79
Q

Various skin diseases (eg Scleroderma) can be caused by the accumulation of what protein?

A

Elastin

80
Q

What is the inheritance of Marfan syndrome?

A

AD

81
Q

What is the defect to cause Marfan syndrome?

A

Fibrillin 1 (FBN1)

82
Q

What 3 systems in the body are affected from the lack of FBN1 in Marfan syndrome?

A

Ocular
Skeletal
Cardivascular

83
Q

What is the main ocular problem in Marfan syndrome?

A

Lens dislocation

84
Q

What are the Skeletal problems in Marfan syndrome?

A

Ling limbs

Arachnodactyly

85
Q

What is the disorder where there is a defect in laminin 5 or 6, and there is blistering skin and mucous membranes?

A

Junctional Epidermylysis Bullosa (JEB)

86
Q

What is the disorder where there is a defect in laminin 2 (links muscle and ECM), causing muscle weakness?

A

Congenital Muscular Dystrophy

87
Q

What are the molecules that are long, unbranches, repeat disarrcharides, often sulphated or acetylated, and often attached to hyaluronate?

A

GAGs

88
Q

Which GAG is found in granules of mast cell, liver, lung, and skin?

A

Heparin

89
Q

Which GAG is located on cell surfaces and extracellular, and is involved in cell communicaiton?

A

Heparin sulfate

90
Q

Which GAG is found in cartilage, bone, tendons, ligaments, and cornea, making the most abundant GAG in the body?

A

Chondroitin sulfate

91
Q

Which GAG is widely distributed (esp in skin, vessels, and heart valves), and may be involved in the development of atherosclerosis?

A

Dematan sulfate

92
Q

Where is Keratan sulfate I found?

A

Cornea

93
Q

Where is Keratan sulfate II found?

A

Cartilage

94
Q

What is the only non-sulfated GAG, is present in synovial fluid, vitreous humor and loose CT, and allows tumor cells to migrate?

A

Hyaluronic acid

95
Q

Which molecule si the major proteoglycan in cartilage, interacts strongly with collagen, and contains hyaluronic acid, chondroitin sulfate, and keratan sulfate?

A

Aggrecan

96
Q

What is the molecule that is a chondroitin sulphate-based proteoglycans that is up-regulated in many human tumors and drives metastasis?

A

Versican

97
Q

What are the 2 integral trnasmembrane protein that is associated with the actin cytoskeleton inside the cell and interacts with fibronectin outside of the cell?

A

Syndecan and Thrombomodulin

98
Q

Neurocan, brevican, cerebrocan, and phosphacan are GAGs that are largely restricted to what system?

A

Nervous system

99
Q

All mucopolysaccharidoses are AR except for what syndromee?

A

Hunters syndrome (XR)

100
Q

In mucopolysaccharidoses, the defects of degredation of what 2 things can cause skeletal and CT abnormalitis?

A

Keratan sulphate

Demartan sulphate

101
Q

Only defects in what molecule in mucopolysaccharidoses cuases MR and neurological degeneration?

A

Heparan sulphate

102
Q

Hurler, Scheie, and Sly can cause what eye abnormality?

A

Corneal clouding

103
Q

Which 2 GAGs do not accumulate in mucopolysaccharidoses because they have an alternative pathway of degradation?

A

Chondroitin sulphate

Hyaluronic acid

Dermatology (4 decks)

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