Membranes, Organells, Cytoskeleton - Symes Flashcards
__ are the site of intracellular degredation
lysosomes
are lysosomes acidic or basic?
acidic
T/F the endomembrane system includes all of the following:
- plasma membrane
- ER
- golgi
- lysosomes
- nuclear envelope
true
neucleoulus is the site of..
rRNA transcription
ribosome assembly
telomerase assembly
T/F the ER and golgi are continuous with the outer nuclear membrane
true
in the lysosome:
proteases degrade …
nucleases degrade …
other enzymes degrade…
proteins
RNA and DNA
polysaccharides and lipids
microfilaments are made of…
actin
mircotubules are made of…
tubulin
intermediate filaments are made of…
multiple proteins including vimentin, desmin, keratin, and neurofilaments
vimentin, desmin, keratin, and neurofilaments are all subunit proteins of…
microfilaments
what are 3 ways lipids can move in a membrane
laterally
rotationally
trans (flip-flop)
glycerophospholipids, sphingolipids, and cholesterol compose…
the 3 major lipids of biological membranes
what is the structure of a glycerophospholipid
polar head connected to one saturated and one unsaturated fatty tail through a phosphate and a glycerol group
describe heredetery sphyrocytosis
in the RBC:
- spectin proteins form a stuctural latticework along membrane surface
- ankyrin and band 4.1 adaptor proteins connect spectrin lattice to membrane at band 3 integral membrane proteins
- defects in any of these proteins can cause spherical cells instead of biconcave cells
- sphericytes cannot squeeze through capillaries and lose membrane and lyse
what are 4 proteins that, if mutated and defective, can cause hereditary spherocytosis
spectrin - lattice work along RBC membrane
ankyrin - connects spectrin to band 3
band 4.1 - connects spectrin to band 3
band 3 - integral membrane protein
in a membrane, what is a:
surface protein
peripheral protein
integral protein
surface protein - on outer surface
peripheral protein - associated with one side
integral protein - spans whole membrane
what is normal physiolgical temp in C and F
37 C
98.6 F
what is pneumonia and what does it look like on chest xray
- lung infection
- hazy area
how are sphingolipids different from gycerophospholipids
derived from sphingosine not glycerol
otherwise similar
failure to dispose of what type of membrane lipid most commonly results in lysosomal storage disease?
sphingolipids
a cherry-red spot in the retina is caused by what disease?
Tay-Sachs disease
lysosomal storage disease
Tay-Sachs disease Fabray's disease Gaucher disease Niemann-Pick disease GM1 gangliosidosis are all what kind of disease?
lysosomal storage disease
(all due to mutations in sphingolipase enzymes – and Niemann-Pick may also be caued by mutations in lysosomal cholesterol transporters)
Tay-Sachs disease is caused by
a mutation in a lysosomal enzyme that normally breaks down sphingolipids
Fabry’s disease is caused by
a mutation in a lysosomal enzyme that normally breaks down sphingolipids
Gaucher disease is caused by
a mutation in a lysosomal enzyme that normally breaks down sphingolipids
Niemann-Pick disease is caused by
mutations lysosomal cholesterol transporters and enzymes that normally breaks down sphingolipids
GM1 gangiosidosis is caused by
a mutation in a lysosomal enzyme that normally breaks down sphingolipids
describe atypical pneumonia
- caused by inhaled bacteria
- extracts cholesterol from mucus membranes
- causes cilia to go limp (not beat)
- muchus accumulation for richer bacterial medium
most transmembrane proteins are glycosylated on the __ side of the plasma membrane
non-cytosolic side
T/F carbohydrates on the lipid membrane play roles in cell-cell recognition, adhesion, and receptor function
true
what are liposomes
bilayered vesicles often used for drug delivery
- can make temperature sensitive to target
- can attach antibodies to target
2 ways to target liposomes for drug delivery
- make temperature sensitive so release contents at site of inflammation or cancer
- attach antibodies to target to particular antigen
how is membrane fluidity affected by temp increase
more fluid (more kinetic energy)
how is membrane fluidity affected by fatty acid chain length
less fluid (more hydrophobic interactions)
how is membrane fluidity affected by more unsaturation
more fluid (cannot pack together so well)
how is membrane fluidity affected by more cholesterol
less fluid (usually)
cystic fibrosis is caused by a defect in what protein?
ABC ATPase pump for Cl-
describe hutchison Gilfor progeria syndrom
defect in nuclear laminin causes disruption of shape, function, mitosis, etc cell death
T/F the nuclear envelope is made of a lipid bilayer
false - made of 2 lipid bilayers
inner and outer nuclear membranes
is the nuclear lamina associated with the inner or outer nuclear membrane?
inner
T/F the outer nuclear membrane is continuous with the ER
true
what is the nuclear matrix?
a complex of fibrillous proteins thought to be the site of RNA processing
what is the nuclear lamina?
a thick layer of fibrous proteins associated with inner nuclear membrane, composed of intermediate filaments
what type of cytoskeletal elements form the nuclear lamina?
intermediate filaments
this structure stabilizes nuclear structure
nuclear lamina
this structure anchors chromatin
nuclear lamina
this structure anchors nuclear pore complexes
nuclear lamina
this structure regulates assembly and dissassembly of nuclear envelope during mitosis
nuclear lamina
T/F a nucleus may contain multiple nucleoli
true
what are Nups
nuecleoporins
8 Nups form an NPC nuclear pore complex
how many proteins form an NPC nuclear pore complex
8 Nups nucleoporins
3 classes of Nups
- transmembrane Nups
- structural Nups
- FG Nups (phe and gly residues forming permeability barrier)
what is the funciton of FG Nups
phe and gly residues form fishnet permeability barrier to larger molecules
T/F hyrdophobicity is a big factor in transport through NPCs nuclear pore complexes
false - size and NLS (nuclear localization signal) are the biggest factors
how does an NLS nuclear localization signal work
- NLS binds importins (nuclear import receptors) in cytosol
- NLS importin complex repeatedly binds/unbinds FG Nups to travel across NPC
how does an importin (nuclear import receptor) work
- importin binds molecule with NLS
- facilitates travel across FG Nups (binding/unbinding repeatedly)
- once in nuclease, release cargo, exit to cytosol
what 2 tests are performed to deterimine if prostate cancer has metastasized to another suspected location?
PET/CT scan
biopsy
in α-β tubulin dimers, which points to the + end and which points to the - end of the microtubule filament?
β + end
α - end
what are three tubulin monomers
α, β, γ
what is the role of γ tubulin
assembles at - end to template correct assembly of microtubule
what are the + and - ends of a cytoskeletal filament?
\+ = fast growing end - = slow growing end
which are the most often targeted cytoskeletal elements for chemotherapy?
microtubules
what are e microtubule motor proteins?
dynein
kinesin
how many forms of α and β tubulin are there?
3 α types
5 β types
what protein stabilizes microtubules on the - end?
MTOC
what is a MAP protein
microtubule associated protein (e.g. tau)
stabilize microtubules
this cytoskeletal element functions in shape, locomotion, contraction, cytokinesis, phagocytosis, and platelet aggregation
actin
how many actin subunit types are there
3
α,β,γ
how many actin subunit types form an actin filament?
only one type per filament
α, β, or γ
T/F actin is the most commonly targeted cytoskeletal element for drugs
false - microtubules
actin drugs are too toxic for use in humans
how do microtubules assemble
α and β tubulin dimerize and polimerize into protofilaments which then associate laterally
how many protofilaments in a microtubule?
13
lamins keratins neurofilaments vimentins glial fibrillary acidic proteins GFAPS desmin are all examples of...
intermediate filament proteins
how are intermediate filaments assembled?
- α-helical monomers form protofilaments
- α-helical protofilaments form coiled coil dimer
- dimers associate in antiparallel tetramer
- tetramers pack together in parallel
- 8 tetramers twist into rope-like filament
how many α-helical monomers in a mature intermediate filament?
32? protofilament dimer tetramer 8 tetramers = rope-like filament
cytoskeletal elements:
strung beads
tubes
rope
strung beads - actin
tubes - microtubules
rope - intermediate filaments
3 steps of cell movement
- leading edge
- adhesion/detachment
- movement
what is a lamellipodium
thin sheet-like projection that pulls cell through tissues
filopodia
extension that explores ECM for growth (e.g. neurons and vessels)
lamella
behind lamellipodia, couples actin to myosin II contractility
what forms lamellipodia
polymerizing actin
coflin
severs existing actin filaments
this protein severs existing actin filaments
cofilin
describe actin polymerization with the following proteins
- fibronectin
- integrin
- Rac1
- WASP/WAVE
- Arp2/3
- formin
- cofilin
- fibronectin (ECM) binds membrane integrins
- integrins bind fibronectin, activate Rac1
- Rac1 - activates WASP/WAVE
- WASP/WAVE - activates Arp2/3
- Arp2/3 - promotes actin branching/growth
- formin - stabilizes actin
- cofilin -severs existing actin filaments
how do cells attach to ECM?
fibronectin (ECM protein) binds to integrin
transmembrane receptor protein
what protein facilitates trailing edge detachment in cell movement?
Rho A
what is the function of Rho A in cell movement?
- inhibit Rac1 (inhibit actin polymerization)
- stimulate actomyosin contractility
- detach trailing edge
what proteins facilitate lamellipodia extension?
- integrins bind fibronectin, activate Rac1
- Rac1 - activates WASP/WAVE
- WASP/WAVE - activates Arp2/3
- Arp2/3 - promotes actin branching/growth
- formin - stabilizes actin
- cofilin -severs existing actin filaments
what proteins facilitate leading edge attachment?
fibronectin (ECM protein) binds to integrin
transmembrane receptor protein
what proteins facilitate trailing edge detachment?
- Rho A inhibit Rac1 (inhibit actin polymerization)
- stimulate actomyosin contractility
- detach trailing edge
movement of the cell body is achieved through __ __
molecular clutching
what is retrograde flow in terms of actin polymerization
actin polymerizes on + end, if not anchored, filament is pushed backward
what kind of myosin is relevant in cell movement?
myosin II (non-muscle myosin NMII)
how does molecular clutching work in cell movement
disengaged clutch = integrin not bound to actin
engaged clutch = integrin bound to fibronectin (ECM) and intracellular actin; actin polymerization causes forward force and movement
what proteins are involved in the molecular clutch in cell movement
- integrin, actin, fibronectin
- disengaged clutch = integrin not bound to actin
- engaged clutch = integrin bound to fibronectin (ECM) and intracellular actin; actin polymerization causes forward force and movement
T/F Microtubules are repetitive filaments of covalently bound heterodimers
false - heterodimers are non-covalently bound
