biology med 103 > topic 5B > Flashcards

topic 5B Flashcards

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1
Q

cytoskeleton

A

a network of filaments extending throughout the cytoplasm

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2
Q

the cytoskeleton is composed of 3 types of filaments

A
  1. microfilaments
  2. intermediate filaments
  3. microtubules
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3
Q

the thinnest type of filament, made of actin filaments

A

microfilaments

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4
Q

the type of filament composed of different types of proteins such as keratin

A

intermediate filaments

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5
Q

the thickest type of filaments, made of tubulin filaments

A

microtubules

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6
Q

cytoskeleton functions

A

supports, maintains cell shape, anchors organelles, provides motility

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7
Q

protein subunits of microtubules

A

tubulin

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8
Q

protein subunits of microfilaments

A

actin

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9
Q

functions of microtubules

A
  • mitotic spindle formation
  • shape the cell
  • guide movement of organelles
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10
Q

the continuous polymerization/depolymerization of microtubules depends on

A

GTP hydrolysis

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11
Q

GTP hydrolysis during tubulin polymerization

A
  • GTP attached to β-tubulin hydrolyzes to GDP
  • GTP bound to α-tubulin does not hydrolyze
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12
Q

drugs that affect microtubule stability/formation

A

anti-mitotic drugs - inhibit the mitotic spindle formation

ex: anti-inflammatory and anti-cancer drugs

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13
Q

examples of anti-mitotic drugs

A
  1. colchicine - binds to tubulin monomers to inhibit microtubule polymerization during PROPHASE
  2. taxol - binds to tubulin monomers, stabilizes microtubules by inhibiting their depolymerization during mitotic ANAPHASE
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14
Q

microtubule polymerization begins at

A

microtubule organizing centers (MTOC)

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15
Q

microtubule orientation

A

the (-) end is oriented towards the cell center (MTOC) and the (+) end is towards the periphery

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16
Q

MTOC types

A
  1. centrosome
  2. basal body
  3. polar body
  4. chromosomal kinetochores of mitotic spindle
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17
Q

MTOC in most non-dividing cells

A

centrosome

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18
Q

MTOC in flaggelated and ciliated cells

A

basal body

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19
Q

MTOC in some fungi

A

polar body

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20
Q

MTOC in dividing cells (during metaphase)

A

chromosomal kinetochores of the mitotic spindle

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21
Q

centrosome structure

A
  • has two centrioles
  • each centriole consists of 9 triplets of microtubules (9+0 arrangement)
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22
Q

pericentriolar material

A
  • space around centrosome
  • used in microtubule nucleation
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23
Q

how does pericentriolar material initiate microtubule polymerization

A
  • contains γ-tubulin
    which facilitates the nucleation of the α/β-tubulin dimers by binding to the (-) end of microtubules
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24
Q

microtubules role in motility

A

used as “monorails” for the movement of cellular cargo from the cell center to the periphery

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25
microtubules interact with _____ to produce motility
motor proteins
26
motor proteins
transport cellular cargo toward opposite ends of mictrotubules
27
motor protein involved in transport from periphery to cell center (retrograde to microtubule)
dynein
28
motor protein involved in transport from cell center to periphery (anterograde to microtubule)
kinesin
29
cilia and flagella
permanent locomotor appendages of some eukaryotic cells
30
cilia and flagella structure
consist of an axoneme surrounded by the plasma membrane
31
flagella
single flagellum per cell, snakelike motion ex: sperm cells
32
cilia
multiple, back-and-forth motion ex: protists, trachea cells
33
axoneme
- the central strand of a cilium/flagellum - composed of microtubules (9+2 arrangement)
34
axonemal proteins
1. dynein 2. nexin
35
nexin
protein that connects microtubule doublets (pairs)
36
basal body
protein structure found at the base of a eukaryotic cilium or flagellum - consists of 9 triplets of microtubules (like centrioles)
37
responsible for the bending movement of cilia/flagella
axonemal dynein
38
_____ & _____ have a microtubule (9+2 arrangement) and _____ & _____ have a (9+0 arrangement)
1. cilia and flagella 2. centriole and basal body
39
function of microfilaments
- support cell shape - cell motility
40
an example of how microfilaments support cell shape
microfilaments make up the microvilli core of intestinal epithelial cells
41
two ways microfilaments help with cell motility
1. formation of pseudopodia 2. actin-myosin contractile system (in muscle cells)
42
actin-myosin contractile system
actin filaments and myosin filaments join together to aid in contraction of muscles
43
pseudopodia
transient (non-permanent) locomotor appendages
44
actin monomers
G-actin (globular)
45
actin polymers
F-actin (filamentous)
46
microfilament polymerization
1. G-actin conversion to F-actin 2. energy provided by ATP hydrolysis 3. (+) end - fast polymerization 4. (-) end - slow polymerization F-actin is assembled from G-actin subunits containing bound ATP, the filament grows at the (+) end and dissociation occurs at (-) end
47
intermediate filaments
larger than microfilaments but smaller than microtubules
48
functions of intermediate filaments
- supports cell shape - fix organelles in place - more permanent than other filaments - composed of different protein family categories (ex: keratin)
49
types of intermediate filaments
- keratin - in epithelial cells - desmin - in muscle cells - vimentin - in mesenchymal cells - neurofilaments - in neurons - GFAP - in neuroglia (glia) - lamins - in nuclear envelope
50
mesenchymal cells
cells that develop into the lymphatic and circulatory systems tissues, and connective tissue (bones and cartilage)
51
how do intermediate filaments support cell shape
provide tissues with resistance to mechanical stress
52
keratin
- found in epithelial and epidermal cells - known as cytokeratins in epithelial cell desmosomes - major component of hair and nails
53
desmin
in muscle cells
54
GFAP (glial fibrillary acidic proteins)
polymerized to form glia fibrils
55
neuroglia
non-neuronal cells that maintain homeostasis, form myelin, provide support/protection for neurons - where glia fibrils are found
56
lamins
lamin filaments are found in the inner side of the nuclear membrane
57
cytoskeleton disorders
- chediak-higashi syndrome - kartagener's syndrome
58
chediak-higashi syndrome
- microtubule polymerization inherited defect resulting in reduced fusion of phagosomes & lysosomes during phagocytosis - results in inability to destroy microorganisms by phagocytosis (infections)
59
kartagener's syndrome
- immotile cilia/flagella due to a dynein arm inherited defect - results in male/female infertility and sinusitis
60
extracellular structures
- cell walls of plant cells - ECM of animal cells - intercellular junctions
61
cell wall
extracellular structure of plant cells that distinguishes them from animal cells
62
cells walls are made fun of
cellulose fibers
63
functions of cell walls
- protects plant cells - maintains its shape - prevents excessive uptake of water
64
the extracellular matrix consists of
glycoproteins and proteoglycans
65
glycoproteins
proteins with attached carbohydrate residues ex: collagen, fibronectin, laminin
66
proteoglycans
carbohydrates with attached protein residues
67
ECM functions
support, adhesion, movement, regulation of gene expression
68
major proteins and glycoproteins of the ECM
collagen - major ECM glycoprotein fibronectin - ECM glycoprotein laminin - basement membrane glycoprotein entactin - basement membrane glycoprotein elastin - connective tissue protein
69
proteoglycans of the ECM are composed of ______ + ______
proteins, glucosaminoglycans
70
CAMS (cell adhesion molecules)
cell surface transmembrane proteins that bind to different ECM components
71
extracellular domain CAMs
bind to ECM glycoproteins via a specific tripeptide sequence
72
intracellular domain CAMs
bind to cytoskeletal filaments (microfilaments/intermediate filaments)
73
most abundant protein in the human body
collagen
74
collagen is produced by
fibroblasts and epithelial cells
75
function of collagen
organizes and strengthens the ECM
76
type III collagen and the syndrome associated
- found in skin, blood vessels, uterus - deficient in vascular type Ehlers-Danlos syndrome
77
type IV collagen and the syndrome associated
- located in basement membrane - defective in Alport syndrome
78
basement membrane
specialized ECM type that separates epithelium/mesothelium/endothelium from underlying connective tissue
79
fibronectin
glycoprotein that connects plasma membrane with extracellular molecules ex: connects plasma membrane integrins to collagen
80
stretchy protein in connective tissue
elastin
81
elastin function
allows many tissues to resume their shape after stretching or contracting ex: blood vessels, vocal cords
82
Marfan syndrome
connective tissue disorder caused by a defect in fibrillin, a glycoprotein that forms a sheath around elastin (in elastic fibers)
83
laminin
glycoprotein that connects cells (via integrins) to basement membrane components
84
entactin
connects basement membrane components between (ex: links laminin with collagen in the basement membrane)
85
glucosaminoglycans (GAG)
polysaccharide composed of a repetitive disaccharide unit
86
the only GAG that can be found alone in the body (not linked to a protein)
hyaluronic acid
87
4 GAG groups
1. hyaluronic acid 2. chondroitin sulfate and dermatan sulfate 3. heparin and heparan sulfate 4. keratan sulfate
88
example of a proteoglycan
aggrecan
89
aggrecan aggregate =
aggrecan + hyaluronic acid
90
types of intercellular junctions
- tight junctions - desmosomes - gap junctions - plasmodesmata
91
plasmodesmata
junctions between plant cell walls, which allows molecule exchange
92
3 animal cell junctions
gap junctions, tight junctions, desmosomes
93
animal cell junction that prevents intercellular communication (molecule exchange)
tight junctions
94
animal cell junction that anchors cells through ECM
desmosomes
95
animal cell junction that channels and allows molecule exchange between cells
gap junctions
96
______ anchor desmosomes in the cytoplasm
intermediate filaments (made of keratin in epithelial cells)
97
what cell junction do intermediate filaments form
desmosomes
biology med 103
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