Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
91 Cards in this Set
- Front
- Back
4 Functions of Cytoskeleton |
Shapes Organizes Organelles Interact Mechanically with the Environment Carry Out Coordinated Movements |
|
Subunit of Intermediate Filaments |
heterogenous family of fibrous proteins |
|
Subunit of Microtubules |
Dimer of alpha and beta tubulin |
|
Subunit of microfilaments |
Actin |
|
Rate MT, MF, and IF from smallest to largest |
MF |
|
Often connect to the plasma membrane at desmosomes |
Cytoplasmic IFs |
|
Nuclear lamins that assemble into a mesh that supports the nuclear envelope |
Nuclear IFs |
|
Defects in nuclear lamin can cause... |
Progeria |
|
4 Protein filaments that make up IFs and where they're found |
Keratin filaments: epithelial cells Vimentin: connective tissue Neurofilaments: nerve cells Nuclear lamins: all animal cells |
|
FIbrous proteins bind together and twist to form... |
Intermediate filaments |
|
In intermediate filaments, the monomer consists of... |
an alpha helical central rod domain |
|
Do IFs have polarity? |
No |
|
What stabilizes IFs and connects them to other parts of the cytoskeleton? |
Plectins |
|
What are the 3 roles of MTs in the cell? |
Cell organization/intracellular transport Spindle assembly Structural support of cilia and flagella |
|
MTs have polarity. Which end is the plus end and minus end? |
Beta: plus Alpha: minus |
|
Where are MTs nucleated from? |
Gamma-tubulin complexes in centrosomes |
|
Dynamic instability occurs in MTs when |
they grow and shrink rapidly |
|
Beta tubulin is a |
GTPase |
|
Growing MTs have a |
GTP cap |
|
Conformation of GDP tubulin favors |
disassembly |
|
MT dynamics are controlled by what 2 things? |
GTP caps Microtubule associated proteins (MAPS) |
|
What does the drug taxol do? |
disrupts spindle assembly binds and stabilizes MTs |
|
What do the drugs Colchinine and Vinblastine do? |
Bind subunits and prevent MT assembly Disrupts spindle assembly |
|
2 Motor proteins for MTs and which direction they move: |
Dynein: minus end Kinesin: plus end |
|
Kinesin and Dynein movement is due to |
conformational changes powered by ATP hydrolysis |
|
Motor proteins arrange what two organelles |
Golgi and Er |
|
_____ coordinates cilia and flagella movement |
Ciliary dynein |
|
4 Roles of actin |
Microvilli Contractile bundles Protrusions needed for cell movement Cytokinetic contractile ring |
|
MFs are composed of globular ___proteins aligned with 2 twisted _______
|
Actin Protofilaments |
|
Explain MFs polarity |
Actin is more likely to be added to the plus end. |
|
Actin is an |
ATPase |
|
Actin-ATP is added to both ends but faster growth at the |
plus end |
|
Treadmilling occurs in |
MFs |
|
What does the drug Phalloidin do? |
binds and stabilizes filaments |
|
What does Cytochalasin do? |
Caps filament plus ends, prevents polymerization |
|
What does Latrunculin do? |
Binds actin monomers and prevents polymerization |
|
Some MFs are nucleated by |
actin nucleating proteins |
|
Lamellipodia |
Branched actin network |
|
Filopodia |
unbranched actin network |
|
Lamellipodia are nucleated by |
ARP complexes |
|
Growth of unbranched filaments in Fillopodia are promoted by |
formins |
|
Integrins |
Bind to the extracellular proteins and internal MFs |
|
Internal contraction of the cell is mediated by |
Myosin II |
|
Rho promotes |
contractile bundles |
|
Rac promotes |
lamellipodia |
|
Cdc42 promotes |
Fillopodia |
|
Muscle cells contain ______ which are chains of repeating _____ units |
Myofibrils; sarcomere |
|
specialized region of the Er that holds CA2+ |
Sarcoplasmic reticulum |
|
What does tropomyosin do? |
covers MFs and prevents myosin from binding (resting muscle cell) |
|
4 phases of the cell cycle and what happens in each: |
1. G1 phase (gap): cell growth 2. S phase (synthesis): DNA replication 3. G2 phase (gap): cell growth 4. M phase: mitosis and cytokinesis |
|
CDK role in cell division |
kinase that activates cellular machinery * constant amount, but cyclical activation |
|
What activates CDK? |
cyclin |
|
How are cyclin concentrations regulated? 2 ways and how |
Transcription: increase in cyclins Proteolysis: decrease in cyclins |
|
What promotes cyclin transcription for entry into S phase? |
mitogens by activating G1-Cdk and G1/S-Cdks which inactivateRetinoblastoma (Rb) proteins. |
|
What is the difference between G0 and G1? |
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
|
|
What cells dismantle the cell cycle control system completely |
muscle and nerve cells |
|
What cell is usually in G0 but can revert back to G1 if needed? |
Liver cells |
|
Mitogens |
extracellular signal that stimulate cell division by the production of thecyclins. |
|
The Retinoblastoma protein |
blocks cellsfrom entering the cell cycle by inhibiting cyclintrascription
|
|
p53 |
Inactivation of G1/Sand S-Cdks during G1and S for DNA repair.
|
|
What happens if there is DNA damage? |
Activation of p53, Production of p2, Inhibition of cyclin-Cdkcomplexes DNA damage can arrest thecell cycle in G1
|
|
Centrosome cycle is triggered by_____in G1 |
G1/S Cdk and S-Cdk
|
|
What are the 4 steps in the initiation of replication (S phase) |
look at the slides |
|
Sister chromatids are held together by |
cohesin rings |
|
When chromosomesare copied during S phase, they are called |
sister chromatids |
|
Activation of M CDK by ___ leads to entry into M phase |
Cdc25 |
|
What 2 things must be duplicated before the cell can enter mitosis |
centrosome and DNA |
|
What two things happen during prophase |
mitotic spindle begins to form chromosomes condense |
|
Phosphorylation by M CDK triggers formation of _____complexes that condense chromasomes |
condensin |
|
In prophase, motorproteins and MAPs __ __ __formingthe mitotic spindle.
|
Crosslink interpolar microtubules |
|
2 Things that happen in prometaphase |
Nuclear envelope disappears MTs attach to kinetochores |
|
How is the nuclear envelope broken down |
phosphorylation of the nuclear pore proteins and lamins |
|
What happens during metaphase? |
Chromosomes line up on the metaphase plate. |
|
Aurora Kinase B |
detects tension and promoteskinetochore microtubule stability
|
|
What 3 things happen in anaphase? |
Chromatids separate Kinetochore MTs get shorter Spindle poles move apart |
|
Anaphase begins with |
the breakageof the cohesin linkages that hold sisterchromatids together (by enzyme separase)
|
|
Securin is an inhibitory protein for |
separase |
|
Active APC leads to |
ubiquitylation and destruction of securin |
|
What happens in Anaphase A and B |
Kinetochore MTs shorten in AA Sliding force of interpolar MTs push poles apart in AB |
|
What 4 things happen during telophase? |
Chromosomes arrive at opposite ends of cell Contractile ring starts to form Nuclear envelope is reassembled Chromosomes decondense |
|
The contractile ring is made of
|
actin and myosin filaments |
|
Contractile ring assembly is mediated by |
RhoA |
|
Phragmoplast |
In plant cells, the interpolar MTs that form the cell walls |
|
Programmed cell death |
apoptosis |
|
Apoptosis is mediated by what family of proteases |
caspase |
|
What family of proteins promotes AND inhibits apoptosis |
Bcl2 |
|
Promote apoptosis by releasing cytochrome c from the mitochondria |
Bax and Bak |
|
Inhibits apoptosis by inhibiting Bax and Bak |
Bcl2 |
|
Promotes apoptosis by inhibiting Bcl2 |
Bad |
|
2 examples of mitogens |
Platelet-derived growth factors – promoteswound repair–
Hepatocyte growth factor – promotes liver celldivision |
|
inhibits growth and proliferation of myoblasts |
myostatin |