Cell Bio

Front 1

4 Functions of Cytoskeleton

Back 1

Shapes

Organizes Organelles

Interact Mechanically with the Environment

Carry Out Coordinated Movements

Front 2

Subunit of Intermediate Filaments

Back 2

heterogenous family of fibrous proteins

Front 3

Subunit of Microtubules

Back 3

Dimer of alpha and beta tubulin

Front 4

Subunit of microfilaments

Back 4

Actin

Front 5

Rate MT, MF, and IF from smallest to largest

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MF

Front 6

Often connect to the plasma membrane at desmosomes

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Cytoplasmic IFs

Front 7

Nuclear lamins that assemble into a mesh that supports the nuclear envelope

Back 7

Nuclear IFs

Front 8

Defects in nuclear lamin can cause...

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Progeria

Front 9

4 Protein filaments that make up IFs and where they're found

Back 9

Keratin filaments: epithelial cells

Vimentin: connective tissue

Neurofilaments: nerve cells

Nuclear lamins: all animal cells

Front 10

FIbrous proteins bind together and twist to form...

Back 10

Intermediate filaments

Front 11

In intermediate filaments, the monomer consists of...

Back 11

an alpha helical central rod domain

Front 12

Do IFs have polarity?

Back 12

No

Front 13

What stabilizes IFs and connects them to other parts of the cytoskeleton?

Back 13

Plectins

Front 14

What are the 3 roles of MTs in the cell?

Back 14

Cell organization/intracellular transport

Spindle assembly

Structural support of cilia and flagella

Front 15

MTs have polarity. Which end is the plus end and minus end?

Back 15

Beta: plus

Alpha: minus

Front 16

Where are MTs nucleated from?

Back 16

Gamma-tubulin complexes in centrosomes

Front 17

Dynamic instability occurs in MTs when

Back 17

they grow and shrink rapidly

Front 18

Beta tubulin is a

Back 18

GTPase

Front 19

Growing MTs have a

Back 19

GTP cap

Front 20

Conformation of GDP tubulin favors

Back 20

disassembly

Front 21

MT dynamics are controlled by what 2 things?

Back 21

GTP caps

Microtubule associated proteins (MAPS)

Front 22

What does the drug taxol do?

Back 22

disrupts spindle assembly

binds and stabilizes MTs

Front 23

What do the drugs Colchinine and Vinblastine do?

Back 23

Bind subunits and prevent MT assembly

Disrupts spindle assembly

Front 24

2 Motor proteins for MTs and which direction they move:

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Dynein: minus end

Kinesin: plus end

Front 25

Kinesin and Dynein movement is due to

Back 25

conformational changes powered by ATP hydrolysis

Front 26

Motor proteins arrange what two organelles

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Golgi and Er

Front 27

_____ coordinates cilia and flagella movement

Back 27

Ciliary dynein

Front 28

4 Roles of actin

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Microvilli

Contractile bundles

Protrusions needed for cell movement

Cytokinetic contractile ring

Front 29

MFs are composed of globular ___proteins aligned with 2 twisted _______

Back 29

Actin

Protofilaments

Front 30

Explain MFs polarity

Back 30

Actin is more likely to be added to the plus end.

Front 31

Actin is an

Back 31

ATPase

Front 32

Actin-ATP is added to both ends but faster growth at the

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plus end

Front 33

Treadmilling occurs in

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MFs

Front 34

What does the drug Phalloidin do?

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binds and stabilizes filaments

Front 35

What does Cytochalasin do?

Back 35

Caps filament plus ends, prevents polymerization

Front 36

What does Latrunculin do?

Back 36

Binds actin monomers and prevents polymerization

Front 37

Some MFs are nucleated by

Back 37

actin nucleating proteins

Front 38

Lamellipodia

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Branched actin network

Front 39

Filopodia

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unbranched actin network

Front 40

Lamellipodia are nucleated by

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ARP complexes

Front 41

Growth of unbranched filaments in Fillopodia are promoted by

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formins

Front 42

Integrins

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Bind to the extracellular proteins and internal MFs

Front 43

Internal contraction of the cell is mediated by

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Myosin II

Front 44

Rho promotes

Back 44

contractile bundles

Front 45

Rac promotes

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lamellipodia

Front 46

Cdc42 promotes

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Fillopodia

Front 47

Muscle cells contain ______ which are chains of repeating _____ units

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Myofibrils; sarcomere

Front 48

specialized region of the Er that holds CA2+

Back 48

Sarcoplasmic reticulum

Front 49

What does tropomyosin do?

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covers MFs and prevents myosin from binding (resting muscle cell)

Front 50

4 phases of the cell cycle and what happens in each:

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1. G1 phase (gap): cell growth

2. S phase (synthesis): DNA replication

3. G2 phase (gap): cell growth

4. M phase: mitosis and cytokinesis

Front 51

CDK role in cell division

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kinase that activates cellular machinery

* constant amount, but cyclical activation

Front 52

What activates CDK?

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cyclin

Front 53

How are cyclin concentrations regulated? 2 ways and how

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Transcription: increase in cyclins

Proteolysis: decrease in cyclins

Front 54

What promotes cyclin transcription for entry into S phase?

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mitogens

by activating G1-Cdk and G1/S-Cdks which inactivateRetinoblastoma (Rb) proteins.

Front 55

What is the difference between G0 and G1?

Back 55

In G0, the cell-cycle control system is partlydismantled, so that some of the Cdks and cyclins arenot present. Cells paused in G1, by contrast, stillcontain all the components of the cell-cycle controlsystem. Whereas the latter cells can rapidly progressthrough the cycle when conditions are right, G0cellsneed to synthesize the missing cell-cycle controlproteins so as to re-enter the cycle, which usuallytakes 8 hours or more

Front 56

What cells dismantle the cell cycle control system completely

Back 56

muscle and nerve cells

Front 57

What cell is usually in G0 but can revert back to G1 if needed?

Back 57

Liver cells

Front 58

Mitogens

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extracellular signal that stimulate cell division by the production of thecyclins.

Front 59

The Retinoblastoma protein

Back 59

blocks cellsfrom entering the cell cycle by inhibiting cyclintrascription

Front 60

p53

Back 60

Inactivation of G1/Sand S-Cdks during G1and S for DNA repair.

Front 61

What happens if there is DNA damage?

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Activation of p53, Production of p2, Inhibition of cyclin-Cdkcomplexes DNA damage can arrest thecell cycle in G1

Front 62

Centrosome cycle is triggered by_____in G1

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G1/S Cdk and S-Cdk

Front 63

What are the 4 steps in the initiation of replication (S phase)

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look at the slides

Front 64

Sister chromatids are held together by

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cohesin rings

Front 65

When chromosomesare copied during S phase, they are called

Back 65

sister chromatids

Front 66

Activation of M CDK by ___ leads to entry into M phase

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Cdc25

Front 67

What 2 things must be duplicated before the cell can enter mitosis

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centrosome and DNA

Front 68

What two things happen during prophase

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mitotic spindle begins to form

chromosomes condense

Front 69

Phosphorylation by M CDK triggers formation of _____complexes that condense chromasomes

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condensin

Front 70

In prophase, motorproteins and MAPs __ __ __formingthe mitotic spindle.

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Crosslink interpolar microtubules

Front 71

2 Things that happen in prometaphase

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Nuclear envelope disappears

MTs attach to kinetochores

Front 72

How is the nuclear envelope broken down

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phosphorylation of the nuclear pore proteins and lamins

Front 73

What happens during metaphase?

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Chromosomes line up on the metaphase plate.

Front 74

Aurora Kinase B

Back 74

detects tension and promoteskinetochore microtubule stability

Front 75

What 3 things happen in anaphase?

Back 75

Chromatids separate

Kinetochore MTs get shorter

Spindle poles move apart

Front 76

Anaphase begins with

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the breakageof the cohesin linkages that hold sisterchromatids together (by enzyme separase)

Front 77

Securin is an inhibitory protein for

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separase

Front 78

Active APC leads to

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ubiquitylation and destruction of securin

Front 79

What happens in Anaphase A and B

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Kinetochore MTs shorten in AA

Sliding force of interpolar MTs push poles apart in AB

Front 80

What 4 things happen during telophase?

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Chromosomes arrive at opposite ends of cell

Contractile ring starts to form

Nuclear envelope is reassembled

Chromosomes decondense

Front 81

The contractile ring is made of

Back 81

actin and myosin filaments

Front 82

Contractile ring assembly is mediated by

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RhoA

Front 83

Phragmoplast

Back 83

In plant cells, the interpolar MTs that form the cell walls

Front 84

Programmed cell death

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apoptosis

Front 85

Apoptosis is mediated by what family of proteases

Back 85

caspase

Front 86

What family of proteins promotes AND inhibits apoptosis

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Bcl2

Front 87

Promote apoptosis by releasing cytochrome c from the mitochondria

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Bax and Bak

Front 88

Inhibits apoptosis by inhibiting Bax and Bak

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Bcl2

Front 89

Promotes apoptosis by inhibiting Bcl2

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Bad

Front 90

2 examples of mitogens

Back 90

Platelet-derived growth factors – promoteswound repair–

Hepatocyte growth factor – promotes liver celldivision

Front 91

inhibits growth and proliferation of myoblasts

Back 91

myostatin