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Relationships between neighboring cells and the extracellular matrix Flashcards

1
Q

where does the formation of tissues start?

A

emrbyo

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2
Q

what are the two ways that specialized cells for tissue in an embryo?

A
  1. specialized cell junction
  2. migration of cells over great distances to meet up with other cells at a new location and form a tissue
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3
Q

what organism is unicellular but aggregate in groups to resemble multicellular organisms and use contact guidance to do this?

A

myxobacteria

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4
Q

explain how myxobacteria uses contact guidance?

A
  • bacteria leaves behind a trail of extracellular matrix that other myxobacteria can follow
  • movement of a single bacterium is made possible by its interaction with fellow bacteria so the whole colony keeps moving together
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5
Q

what organism migrates over long distances, is an amoeba, and makes aggregation centers that gives rise to spores and more amoebae occuring via chemotaxis?

A

dictyostelium discoideum

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6
Q

define chemotaxis

A

the directed motion of an organism towards a chemical signal

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7
Q

what is the chemical signal of D. discoideum produced during the hydrolysis of ATP?

A

cyclic AMP

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8
Q

Inflammation in one part of the body can induce the release of several signals including _______ and _________ that attract other immune cells to come to the site to clear the infection

A

cytokines
chemokines

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9
Q

Other examples of cell adhesion include the development of the human embryo. In this case, embryonic cells associate with each other using an _____________ that is calcium-dependent.

A

aggregation factor

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10
Q

what are cell junctions?

A

way in which cells are held together in multicellular organisms

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11
Q

what are ways we can see cell junctions?

A

thin-section microscopy
freeze-fracture microscopy

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12
Q

what are the three functional categories of cell junctions?

A
  1. adhering junctions
  2. impermeable junctions
  3. communicating junctions
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13
Q

what is the main type of adhering junction?

A

desmosome

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14
Q

what is the main type of impermeable junction?

A

tight junction

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15
Q

what are the two main types of communicating junctions?

A

gap junctions and chemical synapses

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16
Q

where are desmosomes most commonly found?

A

cardiac muscle
skin epithelium
neck of uterus

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17
Q

what are the three kinds of desmosomes?

A
  1. belt
  2. spot
  3. hemidesmosomes
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18
Q

which desmosomes make a continuous band around each of the interacting cells in an epithelial sheet and are found near the apical end of the cell?

A

belt desmosomes

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19
Q

which desmosomes are like screws that hold cells together at small points of contact and act as anchoring sites for keratin filaments which help form a structural framework for the cytoplasm?

A

spot desmosomes

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20
Q

which desmosome do not join adjacent cells together?

A

hemidesmosome

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21
Q

hemidesmosomes join the basal surface of the cell with ____________

A

basal lamina

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22
Q

which two desmosomes work together to spread any shearing force through the epithelium?

A

spot and hemidesmosomes

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23
Q

describe bullous pemphigoid

A
  • disease characterized by blister formation causing the epithelium to detach from the basal lamina
  • pruritic skin disease common in people over 60
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24
Q

what is bullous pemphigoid caused by?

A

autoimmune attack on different protein components of the hemidesmosome

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25
what can the presence of bullous pemphigoid blisters be a side effect from?
furosemide or vildagliptin
26
what is the main function of the epithelial cell sheets that line all body cavities?
highly selective barrier to prevent the mixing of fluids from both sides
27
how are epithelial cell sheets mediated?
tight junctions
28
where are tight junctions commonly found?
transitional epithelium/urothelium
29
why are tight junctions important for the urinary tract?
to prevent urine from being reabsorbed into the body, it retains the seal even when the epithelium is stretched when the bladder is full
30
what is the most common type of cell junction and found in many different tissues?
gap junction
31
what is the purpose of gap junctions?
communicating junction that allow small, water soluble molecules to pass directly between the cytoplasm of one cell to the other - couples the cell electrically and metabolically
32
what are examples in the body of gap junctions?
1. cardiac muscle: gap junctions connect the heart muscle cells with neighboring cells to synchronize their contractions so that the entire chamber of the heart can contract and relax together. 2. nerve cells: allow the spread of an action potential quickly from one cell to the next
33
what are the protein assemblies that make up gap junctions?
connexons
34
how many connexon proteins are connexons made up of?
6
35
One Connexon is a ________, and each cell provides one half to make an interacting, complete gap junction. It comes together like a snap button.
hemichannel
36
list what the extracellular matrix (ECM) is an important component of?
cartilage tendons basal laminae bones teeth
37
what are some functions of ecm?
form or support for cells and can regulate cellular behavior
38
what molecules of the ecm are synthesized and secreted by local cells?
fibroblasts
39
what are the two main classes of molecules that make up the ecm?
collagens and glycosaminoglycans
40
what are glycosaminoglycans (GAGs) linked to what protein?
proteoglycans (PGs)
41
what does the collagen fibers of the ECM do?
provide strength and organization for the matrix and "aqueous" nature of the matrix allows for diffusion of nutrients, metabolites, and hormones between blood and tissue cells
42
list other components of the ECM besides collagen
elastin fibronectin laminin
43
what are collagens
most abundant fibrous proteins found in all multicellular animals
44
what is collagen composed of?
triple helix of three alpha-chains that make a rigid rope like structure that can be cross-linked with the matrix
45
what is the very specific amino acid sequence that makes up collagen?
every third amino acid is a glycine with many proline and hydroxyproline residues that promote "kinking" and help collagen coil tightly
46
what is the main amino acid residue that maintains the stability of collagen?
hydroxyproline
47
how is the hydroxyproline formed?
hydroxylation of proline residues on the collagen molecule through the action of prolyl hydroxylase that requires vitamin C as a cofactor
48
which collagen fiber type is the largest collagen fiber and present in 90% of the connective tissue including bone
type I
49
which collagen type is fine and present in cartilage?
type II
50
which collagen fiber type is fibrillar and present in many tissue?
type III
51
what is another name for osteogenesis imperfecta type I?
brittle bone disease
52
osteogenesis imperfecta type I is caused by a mutation in either of which two type I collagen genes?
COL1A1 and COL1A2
53
the formation of the two genes COL1A1 and COL1A2 leads to the formation of what?
two pro-alpha1 chains and one pro-alpha2 chain that come together to form the triple helix of collagen type I
54
what are signs of osteogenesis imperfecta tarda?
- long bone fractures during childhood after minor trauma (commonly mistaken for abuse) - hearing loss - blue sclera
55
what is the purpose of elastin?
a "spring" that allows for the recoil of tissues back to their original state
56
how is the cross-linkage in elastin possible?
through oxidation of lysine residues
57
how is the oxidation of lysine residues accomplished?
by lysyl oxidase that requires copper as a cofactor
58
When the lysine is oxidized, it forms bonds with other lysine or _______ residues to make ________, which is only found in elastin.
allysine desmosine
59
how many collagen types are there?
5
60
Desmosine is made up of one _____ and 3 _______ residues and has an ___________, which is what gives elastin its characteristic yellow color.
lysine allysine aromatic chain
61
describe marfan syndrome
autosomal dominant disorder caused by a mutation in the fibrillin-1 (FBN1) gene on chromosome 16
62
what is fibrillin?
glycoprotein essential for formation of elastic fibers
63
where are elastic fibers commonly found?
- walls of large arteries (aorta) - suspensory ligaments of the lens in the eye
64
what are distinct characteristics of marfan syndrome?
- long limbs - arachnodactyly - pectus excavatum - lens discoloration - aortic aneurysm - abnormal formation of rib cage

cell bio (12 decks)

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