Functional organization of the cell

Question 1

why can deteregents dissolve phospholipid membranes

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

Answer 1

bc they are amphipathic

much higher [ ]

Question 2

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

Answer 2

sol state

Question 3

low temp PLs diffuse slowly (what state)

Answer 3

gel state

Question 4

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

Answer 4

transition temp (TT)

Question 5

PL w long saturated FA have high or low TT

Answer 5

high TT

Question 6

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

Answer 6

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

Question 7

cholesterol increases or reduces membrane fluidity and how

Answer 7

cholesterol reduces membrane fluidity making it more rigid

rigid steroid rings bind to and partially immobilize FA side chains

Question 8

phospholipid bilayer are impermeable to what and permeable to what

Answer 8

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

Question 9

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

Answer 9

surface facing the cytoplasm (inner) contains phosphatidylethanolamine and phosphatidylserine

outward facing surface composed of phosphatidylcholine

Question 10

integral protein vs peripheral proteins

Answer 10

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

integral - embedded WITHIN the membrane or attached by covalent bonds

Question 11

transmembrane protein

Answer 11

proteins that span the entire plasma membrane

Question 12

the membrane spanning portions of transmembrane proteins and usually what helices

Answer 12

hydrophobic alpha-helices

Question 13

integral proteins can serve as (5)

Answer 13

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

Question 14

integral proteins can serve as recptors that transmit signals between what

Answer 14

the cell and its environment

Question 15

what are integrins and 2 examples

Answer 15

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

Question 16

cadherins

Answer 16

Ca-dependent adhesion molecules

Question 17

N-CAM

Answer 17

Ca-INDEPENDENT neural cell adhesion molecules

Question 18

nucleolus

Answer 18

transcription of rRNA and assembly of ribosomal subunits

Question 19

nuclear lamina

Answer 19

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

Question 20

rough ER function

Answer 20

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

Question 21

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

Answer 21

tagged w ubiquitin
sent to proteasome

Question 22

rER constitutive pathway vs regulated

Answer 22

constitutive - secretion is continious and unregulated (membrane p)

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

Question 23

smooth ER helps w what synthesis and stores what

Answer 23

lipid synthesis
stores calcium

Question 24

golgi

Answer 24

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

Question 25

mitochondria surface of inner membrane consists of folds called what

Answer 25

cristae

Question 26

lysosome

Answer 26

breaks down cellular debris
acidic environment
materials taken by endocytosis fuses w lysosomes

Question 27

epithelial cells

Answer 27

separate te internal milieu from external milieu

Question 28

apical membrane vs basolateral membrane of epithelial cells

Answer 28

apical membrane - face lumen, often topologically continuous w outside world

basolateral - indirectly makes contact w blood and rest on a basement membrane

Question 29

tight junction

Answer 29

impedes passage of molecules and ions
(CLAUDINS/transmembrane proteins)

Question 30

adhering junction

Answer 30

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)

Question 31

desmosomes

Answer 31

holds adjacent cells together tightly at a single round spot
(CADHERINS, PLAQUE, INTERMEDIATE FILAMENTS)

Question 32

gap junction

Answer 32

channels that interconnect cytosol of neighboring cells (allow small molecules to diffuse freely)
(CONNEXONS)