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Cell Bio > Cytoskeleton > Flashcards

Cytoskeleton Flashcards

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Biology 101 flashcards
1
Q

3 types of protein filaments

A

Intermediate filaments
Microtubules
Actin filaments (also known as microfilaments)

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2
Q

Intermediate filaments

A

Span cytosol and link adjacent cells at desmosomes
Give strength to animal cells- allow stretching
Form cell-cell junctions
10 micrometers diameter
Rope-like strands
Often associated with other proteins

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3
Q

Keratins

A

Intermediate filaments in epithelia

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4
Q

Vimentin

A

Intermediate filaments in connective tissue, muscle cells, and glial cells

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5
Q

Neurofilaments

A

Intermediate filaments in nerve cells

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6
Q

Nuclear lamins

A

Nuclear intermediate filaments in all animal cells

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7
Q

Nuclear division

A

Phosphorylation of lamin (nuclear filament) causes lamina to dissemble

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8
Q

Reassembly following telophase

A

Dephosphorylation of lamina

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9
Q

Microtubule locations

A

Interphase cell: attached to centrosome
Dividing cell: mitotic spindles
Ciliated cell: attached to basal body

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10
Q

Tubulin

A

Subunit of microtubules

Attach end to end, giving an alpha (minus) end and a beta (plus) end (polarity)

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11
Q

Centrosome and microtubules

A

Microtubules grow from gamma-tubulin ring complex

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12
Q

Polymerization of microtubules

A

Independent in each microtubule
Depends on tubulin-GTP availability
Dynamic instability: alternates between growing and shrinking
GTP-tubulin stabilizes the end of the microtubule, causing growth of microtubule
GTP hydrolysis: protofilaments containing GDP tubulin peel away from the microtubule wall and GDP tubulin is released into the cytosol

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13
Q

Microtubule-specific drugs

A

Anti-cancer drugs (taxol, colchicine, vinblastine, etc.)
Bind and stabilize microtubules and subunits, preventing polymerization
Cell can’t divide, nervous system doesn’t work properly (microtubules allow transport along neurons)

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14
Q

Capping proteins

A

Stabilize microtubules, resulting in polarization of cell

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15
Q

Kinetochore microtubules

A

Connect to kinetochore (hold sister chromatids together)

Movement of cell parts based on motor proteins

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16
Q

Microtubules and nerve cells

A

Establish polarity of nerve cells

Provide tracks for movement of cargo

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17
Q

Dynein

A

Motor protein that uses microtubules as tracks for movement

Moves towards minus (alpha) end of microtubule

18
Q

Kinesin

A

Motor protein that uses microtubules as tracks for movement

Moves towards plus (beta) end of microtubule

19
Q

“Walking” of motor proteins by ATP hydrolysis

A

ATP binds
Hydrolysis
Release of ADP
Conformational change of motor protein, moving it forward

20
Q

Motor protein function

A

Transport of cargo

Vesicles with proteins destined for secretion or endocytosis, etc.

21
Q

Microtubules and ER and Golgi

A

Organization of ER and Golgi

22
Q

Cilium and flagellum cross section

A

9+2 array of microtubules: prevents sliding of microtubules

Dynein acts on filaments held together by nexin

23
Q

Roles of actin filaments

A

Maintenance of shape and contraction

Microvilli, contractile fibers, amoeboid movement, cell cleavage

24
Q

Microvilli

A

Actin filaments that increase surface area (don’t move)

Increased absorption

25
Q

Structure of actin filaments

A

Assemble with directionality

Plus end and minus end

26
Q

Actin filament polymerization

A

Can proceed from either end
ATP bound actin binds to other actin particles
Actin with bound ADP dissembles

27
Q

Protein interaction with actin

A 
Critical for actin function
Nucleating protein (control where actin binds), bundling protein (in filopodia), motor protein (myosin), capping protein, cross-linking protein (in cell cortex)
28
Q

Actin in the cell cortex

A

Gives cell cortex structure

29
Q

Amoeboid movement

A

Actin polymerization at plus end protrudes lamellipodium (finger-like projections)
Myosin causes contraction at other end

30
Q

ARP complex

A

Branch point of actin filaments

31
Q

Actin-myosin mediated contraction

A

Moves membrane vesicles and allows contraction of membrane

32
Q

GTP binding proteins

A

Actin filaments respond to signaling by these

33
Q

Myosin-II molecule

A

Muscle myosin

34
Q

Contractile ring

A

Myosin-actin interaction

Cell division: pinching off of cells

35
Q

Contractile bundles

A

Myosin-actin interaction

Amoeboid movement

36
Q

Sarcomere

A

Contractile unit of muscle

Compose myofibrils which compose muscle cells

37
Q

Z disc

A

Anchorage of actin filaments in muscle

38
Q

Muscle contraction by ATP hydrolysis

A

Attachment: myosin head lacking a bound nucleotide is locked tightly onto an actin filament in a rigor configuration
Release: molecule of ATP binds to back of myosin head and causes myosin to lose affinity for actin and move among the filament
Cock: Head closes around the ATP molecule and hydrolysis of ATP occurs
Force-generation: Myosin binds weakly to actin, causing release of phosphate produced by ATP hydrolysis
Release triggers power stroke, moving myosin forward
ADP is released, and myosin reattaches to actin

39
Q

Sarcoplasmic reticulum

A

Calcium storage in the muscle cell

40
Q

Transverse (T) tubules

A

Formed from invaginations of plasma membrane

Used for signaling in muscle cell

41
Q

Release of calcium in muscle cells

A

Depolarization of T-tubule membrane opens voltage gated calcium channel
Ca+2 is released into cytosol and binds to calcium release channel of sarcoplasmic reticulum membrane, releasing calcium from sarcoplasmic reticulum

42
Q

Tropomyosin

A

Responds to calcium
Attached to actin
Normally blocks myosin-binding site, but when exposed to calcium, it moves, allowing myosin to move

Cell Bio (15 decks)

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