Functional organization of the cell Flashcards

1
Q

why can deteregents dissolve phospholipid membranes

detergents are water soluble at much higher or lower [ ] than phospholipids

A

bc they are amphipathic

much higher [ ]

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2
Q

lateral diffusion can proceed rapidly at high temp (what state)

A

sol state

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3
Q

low temp PLs diffuse slowly (what state)

A

gel state

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4
Q

temp at which the bilayer converts from gel to sol phase is what

A

transition temp (TT)

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5
Q

PL w long saturated FA have high or low TT

A

high TT

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6
Q

what based phospholipids are the most common membrane lipids (so which one is less common)

A

glycerol based phospholipids
(sphingosine-based lipids are less common)

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7
Q

cholesterol increases or reduces membrane fluidity and how

A

cholesterol reduces membrane fluidity making it more rigid

rigid steroid rings bind to and partially immobilize FA side chains

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8
Q

phospholipid bilayer are impermeable to what and permeable to what

A

impermeable to charged and large water-soluble molecules
permeable to small uncharged polar molecules

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9
Q

phospholipid composition is not identical
surface facing cytoplasm (inner) contains what
outward surface is composed of almost exclusively what

A

surface facing the cytoplasm (inner) contains phosphatidylethanolamine and phosphatidylserine

outward facing surface composed of phosphatidylcholine

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10
Q

integral protein vs peripheral proteins

A

peripheral - adhere tightly to the cytoplasmic or surface of plasma membrane

integral - embedded WITHIN the membrane or attached by covalent bonds

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11
Q

transmembrane protein

A

proteins that span the entire plasma membrane

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12
Q

the membrane spanning portions of transmembrane proteins and usually what helices

A

hydrophobic alpha-helices

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13
Q

integral proteins can serve as (5)

A

-receptors
-adhesion molecules
-transporters
-enzymes
-signal transduction components

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14
Q

integral proteins can serve as recptors that transmit signals between what

A

the cell and its environment

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15
Q

what are integrins and 2 examples

A

cell-matrix ADHESION molecules that link cells to components of the extracellular matrix (fibronectin, lamin)

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16
Q

cadherins

A

Ca-dependent adhesion molecules

17
Q

N-CAM

A

Ca-INDEPENDENT neural cell adhesion molecules

18
Q

nucleolus

A

transcription of rRNA and assembly of ribosomal subunits

19
Q

nuclear lamina

A

fibrillar protein skeleton that provides structural support to the nuclear envelope
(proteins known as lamins)

20
Q

rough ER function

A

-synthesis of secretory and membrane proteins
-undergo post-translational modification and folding in lumen of rER

21
Q

if a protein is misfolded or unassembled, it is tagged w what in the rER and sent to where for degradation

A

tagged w ubiquitin
sent to proteasome

22
Q

rER constitutive pathway vs regulated

A

constitutive - secretion is continious and unregulated (membrane p)

regulated - secretion is directed by hormonal or neural signals (secreted p)

23
Q

smooth ER helps w what synthesis and stores what

A

lipid synthesis
stores calcium

24
Q

golgi

A

precessing station for proteins and targets newly formed proteins to the appropriate subcellular area

25
mitochondria surface of inner membrane consists of folds called what
cristae
26
lysosome
breaks down cellular debris acidic environment materials taken by endocytosis fuses w lysosomes
27
epithelial cells
separate te internal milieu from external milieu
28
apical membrane vs basolateral membrane of epithelial cells
apical membrane - face lumen, often topologically continuous w outside world basolateral - indirectly makes contact w blood and rest on a basement membrane
29
tight junction
impedes passage of molecules and ions (CLAUDINS/transmembrane proteins)
30
adhering junction
belt that encircles an entire epitherlial cell just below the level of the tight junction provide clues about the nature and PROXIMITY of their neighbors (CADHERINS, ACTIN FILLAMENTS)
31
desmosomes
holds adjacent cells together tightly at a single round spot (CADHERINS, PLAQUE, INTERMEDIATE FILAMENTS)
32
gap junction
channels that interconnect cytosol of neighboring cells (allow small molecules to diffuse freely) (CONNEXONS)