Cell Bio Quiz 3

Front 1

3 Major Cytoskeletal Proteins

Back 1

~Microfilaments

~Microtubules

~Intermediate Filaments

Front 2

Cytoskeleton

Back 2

filamentous protein network involved in formation of cell shape, organization, and motility that is attached to cell membrane and organelles

Front 3

Microfilaments

Back 3

made of an actin subunit that enables cell membrane organization, (muscle) contraction, and cargo transport

Front 4

Microtubules

Back 4

made of tubulin subunits; serves as a framework for organelles, structural support for flagella/cilia, mitotic spindle

Front 5

Intermediate Filaments

Back 5

used for structural support for nuclear membrane, integrity of cells in tissues, and barrier functions in skin, hair, nail

Front 6

Steps of Polymerization of G-actin

Back 6

-Nucleation

-Elongation

-Steady State

Front 7

Critical Concentration (Cc)

Back 7

the concentration of monomers in equilibrium with filaments (dissociation and association of subunits are at the same rate); also known as a steady state

Front 8

Treadmilling

Back 8

a form of actin filament assembly in which subunits flow through the filament

Front 9

What regulates the rate of assembly and disassembly of actin subunits?

Back 9

Actin-binding proteins

Front 10

Profilin

Back 10

enhances the exchange of ADP for ATP on G-actin; facilitates actin filament assembly

Front 11

Cofilin

Back 11

enhances the rate of loss of ADP-actin from filament (-) end; disassembles the filaments

Front 12

Thymosin-b4

Back 12

binds ATP-G-actin to provide a reservoir of actin for polymerization

Front 13

CapZ

Back 13

a capping protein that binds to the (+) end and blocks actin filament assembly and disassembly at the (+)

Front 14

Formin FH2 domain

Back 14

a donut-shaped dimer that is used as a means for actin nucleation in unbranched filaments

Front 15

What event activates the formin protein?

Back 15

Binding of Rho-GTP to the Rho binding domain of the formin protein

Front 16

Arp2/3 Complex

Back 16

used for actin nucleation that results in a branched conformation present in motile cells; this is done by binding of the complex to an actin filament and WASp

Front 17

What event activates the WASp?

Back 17

Binding of membrane-bound Cdc42-GTP to the rho binding domain and exposing of the acidic domain

Front 18

Dystrophin

Back 18

a protein that keeps the structural integrity of muscle cells; defective dystrophin results in death of muscle myofibrils

Front 19

Myosins

Back 19

actin-based motor proteinspowered by ATP hydrolysis to move along the (+) end of actin filaments

Front 20

Myosin I

Back 20

used in membrane association and endocytosis

Front 21

Power Stroke

Back 21

a term used to describe the release of elastic energy and Pi from a myosin head that causes the head to straighten and the actin filament to move to the left

Front 22

Structure of Skeletal Muscle Sarcomere

Back 22

consist of muscle fibers made of bundles of multinucleated cells which contain a bundle of myofibrils which consist of thousands of sarcomeres

Front 23

CapZ

Back 23

stabilizes the actin filaments by capping the (+) end of the thin filaments at the Z-disk

Front 24

Tropomodulin

Back 24

stabilizes the actin filaments by capping the (-) end of the thin filaments at the Z-disk

Front 25

Titin

Back 25

a giant protein that extends through the thick filaments and attaches to the Z-disk

Front 26

Nebulin

Back 26

binds actin subunits and determines the length of the thin filament

Front 27

Troponin (Tn)

Back 27

a club-like protein complex that is bound to the long alpha-helical TM molecule

Front 28

Sarcoplasmic Reticulum

Back 28

a specialized ER structure in muscle cells that regulates the level of free Ca2+ in myofibrils

Front 29

Ca2+ dependent thin-filaments regulate...?

Back 29

skeletal muscle contraction

Front 30

Myosin ATP Hydrolysis: EXPLAIN!

Back 30

Good job you! Explaining stuff! (see notebook paper entry)

Front 31

Sliding-Filament Model: EXPLAIN!

Back 31

Good job you! Remembering ****! Hooray! (see notebook paper entry)

Front 32

Ca2+ Dependent Thin-Filament Regulation: EXPLAIN!

Back 32

Skeletal muscle contraction. YOU TELL 'EM! (see notebook paper entry)

Front 33

Thick-Filament Regulation: EXPLAIN!!!

Back 33

Smooth muscle and non-muscle cell contraction. YAAS!

Front 34

What is the job of the endocytic pathway?

Back 34

-Take up cholesterol carried in LDL

-Take up iron atoms carried by transferrin

-Remove receptors from cell surface to downregulate activity

Front 35

How does the coat protein recognize the soluble coat proteins?

Back 35

they are recognized indirectly via the membrane cargo-soluble cargo complex

Front 36

What is the role of coat proteins in vesicle fusion and budding?

Back 36

they determine which proteins are admitted into the vesicle and they give curvature of the membrane

Front 37

What vesicle type(s) are used for ER to cis-Golgi transport?

Back 37

COPII

Front 38

What vesicle type(s) are used for cis-Golgi to ER transport?

Back 38

COPI

Front 39

What vesicle type(s) are used for later to earlier Golgi cisternae?

Back 39

COPI

Front 40

What vesicle type(s) are used for trans-Golgi to endosome?

Back 40

Clathrin and adapter proteins

Front 41

What vesicle type(s) are used for plasma membrane to endosome transport?

Back 41

Clathrin and adapter proteins

Front 42

What vesicle type(s) are used for Golgi to lysosome transport?

Back 42

Clathrin and adapter proteins

Front 43

How are G proteins (GTPase) activated?

Back 43

They are switched between active and inactive states by binding to GTP (active) or GDP (inactive)

Front 44

Sar1

Back 44

a G protein that serves as a binding site for coat proteins; it recruits cargo proteins which leads to polymerization of the coat proteins

Front 45

What proteins are involved in COPII coat assembly and disassembly?

Back 45

-Sar1

-Sec23

Front 46

v-SNARE

Back 46

the protein present on vesicles that is recognized by t-SNARE on the target membrane

Front 47

KDEL

Back 47

located on ER-resident soluble proteins and paired with a receptor in the cis-Golgi membrane; COP1 vesicles

Front 48

Mannose 6-phosphate (M6P)

Back 48

present on soluble lysosomal enzymes and targeted to the trans-Golgi membrane; Clathrin/AP1 vesicles

Front 49

Di-acidic

Back 49

present on cargo membrane proteins in ER and target the COPII Sec24 subunit (export from ER); COPII vesicles

Front 50

Cisternal Maturation

Back 50

Anterograde passage and loss of enzymes that eventually transform compartments into it's previous compartment; e.g. trans golgi donating enzymes to medial Golgi, medial to cis, etc.

Front 51

Regulated Secretory Vesicles

Back 51

proteins that selectively diffuse with the presence of a signal that can come in the form of a neural or hormonal signal or protein aggregation

Front 52

Familial Hypercholesterolemia

Back 52

a disease caused by a defection in the endocytosis of LDL which leads to increased cholesterol in the blood

Front 53

What are the 3 pathways for delivery of materials to lysosomes?

Back 53

-Phagocytosis

-Endocytosis

-Autophagy

Front 54

Endocytosis

Back 54

Soluble macromolecules (or membrane proteins) from outside the cell are pinched inward by the membrane, forming endosomes. The resulting endosome then fuses with a primary lysosome

Front 55

Phagocytosis

Back 55

Large, insoluble particles are engulfed by the cell membrane, creating a phagosome. The phagosome then fuses with a primary lysosome

Front 56

Autophagy

Back 56

A fragment of a membrane bound organelle surrounds organelles or cytosolic proteins creating an autophagosome. This fuses with a primary lysosome resulting in a secondary lysosome.

Front 57

What type of actin filaments does Formin nucleate for?

Back 57

unbranched actin filaments

Front 58

What type of actin filaments does Arp2/3 complex nucleate for?

Back 58

branched actin filaments

Front 59

Myosin V

Back 59

a motor protein that functions to transport organelles toward the (+) end of actin filaments

Front 60

Cc+ of monomeric G-actin

Back 60

the critical concentration at which actin polymerization reaches a steady state; above this concentration there is net growth at the (+) end

Front 61

What protein is the direct target of Ca2+ in skeletal muscle contraction?

Back 61

Troponin

Front 62

What protein is the direct target of Ca2+ in smooth muscle contraction?

Back 62

Myosin LC kinase

Front 63

What is caused by interaction of Ca2+ with troponin?

Back 63

myosin binding site on actin filaments are exposed

Front 64

What is caused by interaction of Ca2+ with myosin light chain kinase?

Back 64

Myosin becomes unfolded and myosin filaments are assembled

Front 65

During muscle contraction, to which end of the actin filament does the myosin head walk?

Back 65

Plus end

Front 66

To what structure in sarcomeres does the actin filament connect?

Back 66

Z disk

Front 67

What type of cargo proteins carry the KDEL sequence?

Back 67

ER-resident soluble proteins

Front 68

What type of cargo proteins carry Mannose 6-phosphate sorting signal?

Back 68

Soluble lysosomal enzymes

Front 69

What type of cargo proteins carry the di-acidic sorting signal?

Back 69

membrane cargo proteins in the ER

Front 70

What type of vesicles move cargos with a KDEL sequence?

Back 70

COPI

Front 71

What type of vesicles move cargos with a Mannose 6-phosphate signal?

Back 71

Clathrin/AP1 and Clathrin/AP2

Front 72

What type of vesicles move cargos with a di-acidic signal?

Back 72

COPII

Front 73

What route transports cargos bearing a KDEL sequence?

Back 73

cis-Golgi to ER

Front 74

What route transports cargos bearing a Mannose 6-phosphate signal?

Back 74

1) trans-Golgi to endosomes

2) cell surface to endosomes

Front 75

What route transports cargos bearing a di-acidic signal?

Back 75

ER to cis-Golgi

Front 76

What materials are taken up in autophagy in response to stavation?

Back 76

cytosolic proteins and organelles

Front 77

What is the main protein involved in the expansion of the membrane on the vesicles?

Back 77

Atg8

Front 78

Are vesicles involved in the endocytosis of LDL particles fused with ensosomes/lysosomes?

Back 78

yes

Front 79

Are vesicles involved in autophagy in response to starvation fused with ensosomes/lysosomes?

Back 79

yes

Front 80

What are the biological functions of endocytosis of LDL particles?

Back 80

LDL particles are broken down by lysosomal enzymes, releasing cholesterol for use by cells

Front 81

What are the biological functions of autophagy in response to starvation?

Back 81

Materials taken up are degraded by lysosomal enzymes, generating small molecules for use as nutrients by cells