Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Cell bio > exam 2 > Flashcards

exam 2 Flashcards

cell bio

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

AB MT dimer structure

A
  • alpha tubulin permanently bound to GTP
  • Beta can bind GTP/GDP. hydrolyzes GTP during formation
  • alpha = - end
  • beta= + end
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

MTOC’s

A
  1. Spindle poles: duplicated centrosomes. found in mitosis
  2. Nerve cells:
    - axons: discontinuous. same polarity.
    - dendrites: not associated with MTOC. mixed orientation.
  3. centrosomes: main ones in animals
  4. basal body: cilia/flagella
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Centrioles

A
  • a perpendicular set found in the pericentriolar matrix
  • 9 sets of triplet microtubules
  • yTurc initiates poly of MT’s. Nucleating site. negative end associated with yTurc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Augmin

A

provides nucelating site in cetrioles. Supports polymerizzation in yTurc. Centrioles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Dynamics of MT assembly- GTP/GDP tubulin

A 
GTP= strongly favoured to grow at + end 
GDP= rapid disassembly. weakens cohesion b/w protofilaments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Colchicine

A
  • induces depoly of cytoplasmic MT’s = singlets

- centrosomes remain b/c triplets = stable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Taxol

A

Stabilizes. inhibits mitosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

MAP’s

A

side binding proteins. + domain binds - MT side
MAP2: cross-bridges. Link MT’s to intermediate filaments. Dendrites
Tau: spacer. Axons/dendrites
+TIPs: associate with the growing + end. stabilize. Can attract hitchhikers

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Regulation of MAP’s

A

via phosphorylation

cant bind to MT’s when phosphorylated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Kinesin 13 and Stathmin

A

K13: binds to dimers at the positive end. Promotes depoly. Requires ATP
Stathmin: binds sets of dimers. Promotes disassembly by promoting GTP hydrolysis. inactivated by Phosphorylation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Singlet, Doublet, Triplet examples

A

Singlet: Cytoplasm. Most common
Doublet: cilia/flagella
Triplet: basal body, centrosome (centrioles)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Cytoplasmic vs Axonemal MT’s

A

Cyto is more dynamic

Axonemal are more stable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

MT formation diagram

A
  • Cc of tubulin dimers needed for MT assembly.
  • Cc reached, tubulin dimers are in equilibrium
  • above Cc, most of the mass is from MT’s
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Kinesin

A

Motor proteins for MT’s

  • heavy chains: head, linker, stalk. Head binds ATP and MT’s
  • light chains: bind cargo
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Examples of Kinesins

A

K1: conventional. 2 LC/HC. Anterograde movement
K2: 2 diff HC and 1 LC. Organelle transport. Anterograde
K5: bipolar. 4 HC=4 heads. Sliding of MT to + end
K13: short heavy chain. NOT a motor protein disassembly via ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Kinesin Movement

A
  1. head binds ATP, releases MT.
  2. Conf change in linker. Trailing head swings forward 16nm. Linker docks in head
  3. Leading head releases ADP , lagging head hydrolyses ATP. Linker undocked from head
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Cytoplasmic Dynein

A
  • for organelle transport
  • Negative end retrograde transport
    Stem: links dynein to cargo through dynactin
    Head: ATPase
    Stalk: extension from head, has MT binding site on end
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Dynactin Complex

A
  • links dynein to cargo and regulates movement
  • dynamititin regulates dynactin/cargo association. overexpression= separation of dynein and dynactin
  • p150 glued keeps system attached to MT
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Post trasnlational modification of tubulin

A

acetylated lysine on alpha tubulin = stability and promoes Kinesin 1 movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Axoneme

A
  • cilia/flagella structure
  • 9+2 array
  • doublets connected via Nexin
  • A tubule as axonemal dynein permanently bound
    stem attached to A, stalk attached t
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Axoneme zones

A 
Continuous
Basal body: 9 sets of triplets (below PM). ABC
Transition Zone: 9 doublets. AB
Axoneme: 9+2. AB
- only doublets found above PM
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Axoneme bending

A

= physical movement. Activtion of dynein:
With nexin linkers= bending
Wout nexin linkers: sliding. slide towards Negative end

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Intraflagelular Transport

A
  • doesnt refer to movement
  • transport of organelles
  • cytoplasmic dynein and kinesin 1 utilized
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Primary Cilium

A
  • interphase cell
  • sensory organelle
  • important in cell signalling
  • non-motile
  • NO axonemal dynein
  • 9+0 arrangement of MT
  • stabilized by acetylated alpha tubulin
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Dynamic Instability in Mitosis

A
  • K13 is constitutively expressed.
  • XMAP215 inhibits the affect of K13. Enhances assembly at + end.
    activity fluctuates, decreases before mitosis and increases after, interphase. Can be inhibited by mitosis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Mitotic Apparatus

A
  1. Astral: extend from poles towards to cortex, linked
  2. Polar: towards cell centre. + end overlap= zone of interdigitation
  3. Kinetochore: bind to KT’s of MT
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Spindle Formation

A
  • all chromos must be aligned at meta plate
  • all must be captured
  • can attach at sides or end of MT
  • Bi-orientation: attachment to both sides of MT
  • chromos move towards furtherst pole
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

bi-orientation

A
  • attachment to both sides of MT
  • ensures tension. Tension is required for movement
  • phosphorylation of Ndc80 by Aurora B= no tention
  • dephos by PP1= tension. Strong interaction b/w KT and MT
  • moves toward +end
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Kinesin’s in Spindle formation

A

Kinesin 13: depoly at both the -/+ end.
Kinesin 4: on chromsome, + end movement. Results in ends pointing towards furthest pole
Kinesin 7: keeps growing MT attached to KT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Anaphase

A

A: separtion of sister chromatids
- shrinkage at both MT (+) and spindle pole (-) via kinesin 13
B: separation of spindle poles
- B1: Sliding of MT’s by Kinesin 5. push apart
- B2: pulling to cell cortex by dynein/dynactin. astral MT’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Actin structure

A

Alpa: muscle
Beta: cortex, networks
Gamma: stress fibers
(-) has ATP binding cleft

32
Q

Actin assembly

A
  1. nucleation
  2. elongation. at both ends, preferentially the + end
  3. steady phase. equilibrium b/w monomers and AF’s. constant exchange
33
Q

AF Cc

A

+: 0.12M
-:0.60M
the difference in Cc’s results in treadmilling
ATP-Actin needed for polymerization

34
Q

Regulation of AF polymerization

A

Cellular G-actin in 400uM. Prevents constant poly
Profilin: ADPactin–> ATPactin
Cofilin: disassembly. binds to ADPactin in AF.
Thymosin: Sequesters ATPactin, builds reservoir
CapZ: binds to + end, prevents poly
Tropomodulin: binds to- end, prevents depoly

35
Q

Actin Disrupting Drugs

A

CytochalasinD: binds to AF at + end. Depoly
Latrunculin: sequesters G-Actin. Depoly
Phallodium: stabilizes AF’s

36
Q

Formins

A
  • unbranched assembly
  • nucleating centre
  • activated by Rho-GTP, memrane bound protein
  • FH2 dimer, + end of Actin associated with dimer, - end extends
37
Q

NPF

A

Wasp and Wave

38
Q

Arp2/3

A
  • nucleating centre
  • branched assembly
  • Activated by NPF’s
    WASP acitvated by Cdc42
    WAVE activated by Rac
  • can aid in endocytosis
39
Q

Red Blood cell attachment to PM

A

Spectrin: links AF’s together
Ankyrin: binds spectrin units together and connect AF;s to PM via Glycophorin C

40
Q

Microvilli attachment to PM

A

Via Ezrin

41
Q

Muscle attachment to PM

A

Glycoprotein spans membrane into ECM

Dystrophin binds AF’s and connects them to Glycoprotein

42
Q

Myosin

A
  • AF’s motor protein
  • M2 is most abundant
  • Head: ATPase, actin and nucleotide binding site
  • Neck: essential and regulatory LC.
  • Tail: heavy chain. Binds cargo!!!!
43
Q

myosin cleavage

A

Chymotrypsin: cleaves in middle of heavy chain. HMM (LC+Head and some heavy chain) and LMM (tail)
Papain: cleaves at base of LC (head+LC) and HC

44
Q

Classes of Myosin

A

1: monomer. membrane association and endocytosis
2: dimer. muscle conraction. bind AF’s with tail domain
5. dimer. organelle transport

45
Q

Myosin movement

A
  1. head binds atp, releases from AF
  2. ATP hydrolysis, elastic energy. cocked state
  3. binds actin, releases Pi and elestic energy = powerstroke
  4. head remains tightly bound until atp binds
46
Q

Sarcomere components

A
  • Zdisk: + end of AF associated with Z disk
  • myosin: attached to - end
  • I band: changes in size with contraction
  • A band: remains constant
  • CapZ/tropomodulin
  • Nebulin: binds actin subunits. determines length in sarcomere
  • Titin: binds myosin with the Z stack. prevents it from moving in the sarcomere
47
Q

Sarco reticulum

A
  • stores and regulates Ca2 levels

- is associated with transverse tubules

48
Q

Steps in muscle contraction

A
  1. Depolimerize. impule to transverse tubules
  2. Ca channel opens, Ca release
  3. Ca recoery via ATPase
49
Q

Troponin/Tropomyosin

A
  • calcium binding proteins
  • are bound to AF’s, inhibit the binding of myosin
  • when calcium binds, changes conformation, allows myosin to find its bidning sites
    myosin only interacts with AF’s in presence of Ca
50
Q

Actin has roles in:

A
  • phagocytosis

- cytokinesis: contractile ring

51
Q

skeletal muscle

A
  • regulated by Ca

- striated

52
Q

Smooth muscle

A
  • organs
  • regulated by phosphorylation
  • myosin LC phosphorylated = active myosin
  • much slower and persistant contraction
53
Q

Cell migration

A

Stress fibers: made up of contriactile bundles (sarcomeres)
- are associated with cell adhesion
- associated with PM via Integrins (membrane proteins)
Leading Edge: Pm pushed forward by Actin poly
- treadmilling

54
Q

integrins

A
  • membrane proteins
  • connect stress fibers to plasma membrane
  • associated with the ECM
  • involved in cell migration
55
Q

Migration requirements

A
  • cells need receptors on surface

- Cdc42, Rac, Rho

56
Q

migrating cells examples

A
  • tissue and immune cells
57
Q

Cell migration steps

A
  1. extension: lamellipodium extends from the leading edge
  2. adhesion: lamellipodium adheres to the substrave by focal adherens
  3. translocation: bulk of cytoplasm in cell body flows forward due to contraction at the back of the cell
  4. De-adhesion/Endocytic recycling: tail detaches, retracts. Endo cycle internalizes membrane and integrins at rear, transports them to the front
58
Q

Cdc42-GTP

A
  • filopodium
  • required for polarity
  • activates WASP (NPF), then Arp2/3 branching
  • activates Microtubule capture of lamellipodium
  • dynein activation
  • can activate Rac
59
Q

Rac-GTP

A
  • lamellipodium
  • activates WAVE–> Arp2/3 branching
  • can activate Rho
60
Q

Rho-GTP

A
  • stress fibers and contraction
  • activates formin–> unbranched
  • activates rho kinase–> active myosin
61
Q

Rho proteins/GTPases

A

Cdc42, Rac, Rho

62
Q

Dominant-Active GTPases

A

binds effector molecule consitituively

in absence of GTP

63
Q

Dominant-Negative GTPases

A

inhibits activation of Rho proteins

64
Q

Actin-binding proteins

A
  • Fimbrin: microvilli, filopodia, focal adhesions
  • a-actinin: stress fibers, filopodia, muscle Z line
  • Spectrin: cell cortex
  • Filamin: leading edge, stress fibers, filopodia
  • dystrophin: linking membrane proteins to actin cortex in muscles
65
Q

Intermediate Filaments

A
  • not globular
  • don’t bind nucleotide (don’t need ATP/GTP
  • no polarity
  • no motor proteins
  • less dynamic
  • more stable
  • tetramer
  • add to pre-existing IF
66
Q

Cytoplasm IF proteins

A

Keratins, Desmins, Vimentin, GFAP, Neurofilaments

67
Q

Keratin

A

Class 1 and 2

  • epithelial cells
  • associate with desmosomes and hemidesmosomes
  • tissue strength and integrity
68
Q

Desmins

A

Class 3.

  • muscle cells.
  • muscle integrity
  • smooth muscle: link dense bodies
  • skeletal muscle: surround sarcomere. Encircle Z disk and are cross-linked with PM
69
Q

Vimentins

A

Class 3

  • mesenchymal cells
  • fibroblasts, migratory cells
70
Q

Neurofilaments

A

Class 4

- neurons, support the axon

71
Q

Lamins

A

Class 5

  • maintain the integrity of the nucleus
  • nuclear lamina links to the cytoplasm cytoskeleton via IF-associated proteins (found in LINC)
72
Q

Lamins in mitosis

A
  • need to be degraded to deplete nuc envelope
  • CDK’s phosph lamins, promote IF disassembly and prevents reassembly
  • phosphatases remove phos, reassemble lamins. reform nuc env
73
Q

IF-associated proteins

A
  • organizational, no capping/motors/severing
  • can link nuclear lamina to the cytoplasm cytoskeleton via LINC
  • EX: plectin cross-links IF vimentin and MT
74
Q

desmosomes

A

link epithelial cells

75
Q

hemidesmosomes

A

link epithelial cells to ECM/connective tissue

76
Q

IF function

A
  • provide structural support for cell shape
  • can bind PM and Nuc mem
  • PM: vimentin links to ankyrin
  • NM: via lamins

Cell bio (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions