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Biochemistry > Test 3 - Mokrzan > Flashcards

Test 3 - Mokrzan Flashcards

1
Q

Define extracellular matrix

A

A complex network of macromolecules in the extracellular space

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2
Q

What is the extracellular matrix secreted by?

A

The cells which inhabit it

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3
Q

What is the role of the extracellular matrix?

A

Gives structural and organizational support to tissues

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4
Q

T/F: The extracellular matrix makes up a substantial part of tissue volume

A

True

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5
Q

Collagen makes up ___% of the total body protein?

A

30%

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6
Q

___% of collagen is type __

A

90% of collagen is type I

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7
Q

Collagen has what type of structure? How is this structure strengthened?

A

Collagen has a triple-helical structure, strengthened and stabilized by crosslinks

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8
Q

There are both ____ and ____ collagens

A

Fibrillar and nonfibrillar

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9
Q

T/F: The same types and combinations of collagen molecules predominate in different tissues

A

False. Different types and combinations of collagen molecules predominate in different tissues

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10
Q

Collagen is frequently _____, and synthesis is affected by physiological conditions such as ___ or ___ ____

A

Remodeled

Diet

Mechanical Stress

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11
Q

Osteogenesis/Dentogenesis imperfecta is the result of a genetic mutation that causes:

A

The glycine in Type I collagen to be replaced by another amino acid

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12
Q

What is the role of elastin?

A

It provides flexibility and resilience to the ECM

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13
Q

What is the predominant ECM molecule in blood vessels?

A

Elastin

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14
Q

Where is elastin found?

A

In tissues that require elasticity

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15
Q

How is elastin stabilized?

A

By two-way crosslinks

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16
Q

When do you stop synthesizing elastin?

A

After adolescence

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17
Q

What is the role of fibronectin?

A

Facilitates communication between intracellular and extracellular compartments

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18
Q

T/F: Fibronectin binds to other ECM molesules

A

True

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19
Q

T/F: Fibronectin binds to integrin molecules on cells

A

True

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20
Q

What is fibronectin important for?

A

Cell adhesion, growth, migration, and wound healing

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21
Q

What 2 forms does fibronectin have in order to interact with oral pathogens?

A

Soluble and insoluble forms

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22
Q

Where is laminin found in?

A

Primarily in the basal lamina

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23
Q

What is the role of laminin?

A

Gives structural support to the ECM

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24
Q

Laminin is the major component of:

A

Basement membranes in epithelial and muscle tissues

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25
Q

Laminin binds to cells, often through what?

A

The integrin family of proteins

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26
Q

T/F: You can acquire diseases from abnormal laminin

A

True

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27
Q

What is the function of proteoglycans?

A

They are the gel-formers of the ECM. They also function in the structure of molecules and diversity.

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28
Q

Proteoglycans have many ____

A

Negative charges

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29
Q

The negative charges in proteoglycans attract:

A

Cations and water

30
Q

The result of proteoglycans attracting cations and water is:

A

Hydration of the ECM, which provides rigidity and durability

31
Q

Proteoglycans are < ____% of ECM protein

A

< 10%

32
Q

Because of their hydrophilicity, ____ ____ fill most of the extracellular space

A

GAG chains

33
Q

Proteoglycans combine to form

A

Aggrecan

34
Q

Proteoglycans can also:

A
  1. Bind growth factors

2. Regulate enzyme activity 3. Act as co-receptors

35
Q

What type of diseases are related to proteoglycans?

A

Lysosomal storage diseases

36
Q

Define cell junctions

A

Specialized regions where cells are attached to each other and the ECM

37
Q

What type of tissues are particularly rich in cellular junctions?

A

Epithelial tissues

38
Q

What are tight junctions?

A

Cell-cell junctions found in all epithelia

39
Q

What is the role of a tight junction?

A

To severely limit intercellular permeability and maintain cell membrane polarity (different protein components of apical and basolateral membranes)

40
Q

How are tight junctions formed?

A

By sealing strands anchored in the membrane

41
Q

What are tight junctions required for?

A

For active transport of solutes across the epithelial barrier

42
Q

All tight junctions are impermeable to:

A

Macromolecules

43
Q

T/F: Permeability to small molecules in tight junctions can vary

A

True

44
Q

Permeability of small molecules in tight junctions varies depending on:

A

The number of sealing strands and the different transmembrane proteins (occludin and claudin families) that comprise them

45
Q

What is the role of an anchoring junction?

A

To bind cells to each other and to the ECM

46
Q

Where are anchoring junctions found?

A

In all tissues, especially those subject to mechanical stress

47
Q

What are adherens junctions?

A

Cell-cell junction found primarily in epithelia

48
Q

Adherens junctions form:

A

A continuous adhesion belt just below the tight junction

49
Q

Transmembrane proteins in adherens junctions are

A

Cadherins

50
Q

Adherens Junctions connect:

A

Bundles of actin filaments (contractile)

51
Q

Adherens junctions are necessary for:

A

Tight junction formation and epithelial tube formation in morphogenesis

52
Q

Desmosomes are:

A

Cell-cell junctions that “rivet” cells together

53
Q

Where are desmosomes found?

A

Primarily in epithelia and muscle cells

54
Q

What do desmosomes contribute to?

A

Tissue strength and durability

55
Q

Transmembrane proteins in desmosomes are:

A

Cadherins

56
Q

What do hemidesmosomes resemble?

A

Half-desmosomes

57
Q

What is the difference in hemidesmosomes and half-desmosomes?

A

Hemidesmosomes bind cells to the ECM

58
Q

Transmembrane adhestion proteins in hemidesmosomes are:

A

Integrins

59
Q

Hemidesmosomes attach the junctional epithelium to the:

A

Tooth enamel

60
Q

Focal adhesions are:

A

Spot-type junctions that link the cell cytoskeleton to the ECM

61
Q

Focal adhesions can contain as many as ___ different proteins

A

100

62
Q

How are focal adhesions dynamic?

A

They can form, change, or disappear in response to intracellular or extracellular signals

63
Q

Focal adhesions transmit external mechanical signals via __ ___

A

Integrin receptors

64
Q

Focal Adhesions are important in:

A
  1. Cell migration
  2. Motility
  3. Differentiation
  4. Proliferation
  5. Orthodontic tooth movement
65
Q

What are gap junctions?

A

Communicating junctions found in nearly all cells except skeletal muscle and blood cells

66
Q

What do gap junctions allow for?

A

Small molecules and electrical charges to pass directly from cell to cell

67
Q

Channels, called ____, are hexamers of connexin proteins

A

Connexons

68
Q

T/F: Connexon permeability varies with the identity and combinations of connexins present

A

True

69
Q

Gap junction permeability can be regulated by:

A

Both intra and extracellular signals

70
Q

T/F: Gap junctions allow the cells of a given tissue to function together quickly and in a coordinated fashion

A

True

Biochemistry (6 decks)

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