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Test 2 Cell Bio Flashcards

(68 cards)

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1
Q

Intermediate Filaments

A

long, fibrous, tough, form network to enmesh nucleus and emanate from specialized cell junctions

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2
Q

desmosomes

A

cell to cell junctions (IF)

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3
Q

hemi-desmosomes

A

cell to substrate junctions (IF)

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4
Q

Keratin Filaments

A

Types 1 and 2, arrange into filaments starting with dimer as basic unit, heterodimers - equimolar ratio type 1 and type 2

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5
Q

Type 1 keratin filament

A

acidic

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6
Q

Type 2 keratin filament

A

neutral/basic

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7
Q

hard cytokeratins

A

extensive disulfide bonding to stabilize structure

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8
Q

Vimentin

A

Type 3 intermediate filament - can self assemble into homopolymers (vimentin, desmin, peripherin)

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9
Q

Neurofilaments

A

Type 4 intermediate filament - found in neurons especially axon

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10
Q

Nuclear Lamins

A

Type 5 intermediate filament - form nuclear lamina in all eukaryotic cells

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11
Q

Nuclear Lamina

A

meshwork that stabilizes nuclear envelope and organizes chromatin

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12
Q

Lamins A, B, C

A

contain nuclear localization sequence, assemble in sheets on inner nuclear membrane

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13
Q

Lamin B

A

specific phosphorylation of lamin B involved in regulating lamina disassembly during mitosis

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14
Q

Intermediate filaments subunits

A

N terminal globular head domain
central rod - coiled coil dimers between parallel alpha helices
C terminal globular tail

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15
Q

Subunit assembly of IF

A

2 subunits twist to form central rod with both N terminals at same end - this dimer binds antiparallel to other dimer to form tetramer - tetramers pack to form protofilaments

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16
Q

Microtubules

A

vesicle trafficking, mitotic spindle, cell shape/polarity, organelle positioning

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17
Q

Tubulins

A

gamma at MTOC, alpha and beta subunits form dimer
both have GTP binding site
GTP on alpha never hydrolyzed

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18
Q

Microtubule Organizing Center (MTOC)

A

place from where MT emanate out

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19
Q

Nucleation (Lag Phase)

A

MTOC, tubulin dimers self associate to form rings, rings uncoil to form closed tube

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20
Q

Elongation

A

tubulin heterodimers assemble to form hollow cylinders, beta end is dynamic growing end (plus end)

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21
Q

Drugs influencing MT polymerization

A

Colchicine, Nocodazole: monomer sequestering
Taxol: polymer stabilizing (stops elongation), affects cells trying to divide (cancer)

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22
Q

Dynamic Instability

A

Growing and shrinking on beta end due to GTP hydrolysis

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23
Q

Growth phase

A

tubulin assembly faster than GTP hydrolysis

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24
Q

Shrinking Phase

A

GTP hydrolysis faster than polymerization and GDP bound betas less stable - fall off

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25
Microtubule Associating Proteins (MAPs)
bind along MT and stabilize against disassembly, mediate MT interactions with other cellular components, targets of various kinases
26
Blistering skin disease
mutation in keratin, blisters caused by slight pressure to epidermis, normally keratin resists mechanical stress
27
Microfilament Systems
stable, hexagonal, crystalline, arrays critical for locomotion
28
Actin
thin microfilaments
29
Myosin
thick microfilaments
30
Actin structure
alpha actin - muscle beta, gamma - non-muscle arrange in protofilaments and then two strands twist to form microfilament
31
G actin
globular actin - monomers
32
F actin
filamentous actin - long strands
33
Cytochalasin
caps plus end of actin
34
Latrunculin
binds actin subunits - leads over time to actin depolymerization
35
Phalloidin
actin filament stabilizing - can be tagged with phosphor to observe filaments
36
cell cortex
MF - structural rigidity and stabilization of plasma membrane
37
stress fibers
bundles of actin, myosin, ABPs - contractile tension generating
38
cell surface extensions/protrusions
MF - filopodium, lamellipodium, microvilli
39
Cdc42
GTPases that regulates formation of filopodia
40
Rac1
GTPase that regulates formation of lamellipodia
41
Rho
GTPase that regulates formation of stress fibers
42
Kinesins
molecular motors toward plus end of microtubule (periphery)
43
Dyneins
molecular motors toward minus end of microtubule (MTOC)
44
Kinesin structure
globular N terminus head (binds to MT), stalk (2 chain coiled coil), C terminus fan tail (light chains, bind to cargo)
45
dynein structure
2 heavy chains (ATPase and tubulin binding), 2 intermediate chains (cargo binding), light chains, requires coenzyme dynactin
46
Conventional myosins
type II (self assemble bipolar filaments)
47
myosin structure
head (binds to actin), tail, light chains,
48
myosin II
folded (head hidden) vs extended (head can interact with F - actin) - governed by phosphorylation induced by Ca+/calmodulin
49
Gated transport
small molecules pass easily, large molecules require active transport
50
Transmembrane transport
translocation machinery directs movement across membrane
51
adaptor proteins
bind localization sequences and target polypeptide to correct compartment/organelle
52
nuclear pore complexes (NPCs)
gated pores, bidirectional transport of proteins and nucleic acids - post translational
53
nuclear localization sequence (NLS)
short stretches, rich in Lys, Arg, Pro, NOT excised after transport
54
nucleoporins (nups)
collection of proteins that comprise ring, spokes, filaments, fibrils of nuclear cages
55
importins
hook onto fibril and carry proteins with nls into nucleus, releases protein in nucleus upon binding with Ran-GTP
56
exportin
binds protein and GTP on inside, carries out
57
TOM
outer mitochondrial membrane transport
58
TIM 23
transfers through inner membrane to matrix
59
OXA
reads secondary sequence and pulls protein from matrix into inner membrane
60
TIM 22
helps multipass inner membrane proteins
61
SAM
assembly and insertion of beta barrel proteins into outer mitochondrial membrane
62
Signal Hypothesis
ER transport - leader sequence on precursor protein directs it to ER where cleaved by signal peptidase after transport into ER
63
ER signal leader sequence
often at N terminus, hydrophobic stretch flanked by polar/charged AA
64
Signal Recognition Particle
targets actively translating proteins and their ribosome to surface of ER membrane
65
SRP Receptor
regulates docking and transfer of translational complex to translocation machinery
66
SEC61
ER translocational complex which associates with ribosome and functions as channel through which proteins pass while being synthesized
67
Type I and II transmembrane proteins
Stop transfer sequence while being transferred to ER, (+) side in cytosol, (-) in lumen, if transferred to plasma membrane orientation is conserved
68
GPI anchored proteins
synthesized in ER and attached Asp-GPI by GPI transferase

Cell bio (2 decks)

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