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Flashcards in Chapter Eleven Deck (53):
1

lac operon

control of breakdown of lactose into sugar for metabolism in E.Coli (beta galactosidase)

2

hydrophilic molecules

have charged atoms or groups evens w uneven distribution of pos or neg charges that form electrostatic or H bonds w polar water mols

3

hydrophobic bonds

uncharged, non polar, can't form bonds w water

4

phospholipid bilayer spontaneously closes in

sealed and stable compartment avoids exposure of hydrophobic H-carbon tails to water which would be energetically unfavorable

5

new phospholipid added to

cytosolic side of ER membrane

6

scramblases

transfer new phospholipids from one half of lipid bilayer to other providing symmetry

7

fippases

redistribute phospholipids in lipid bilayer to maintain asymmetry ATP dependent; maintains asymmetric arrangement and important in vesicle budding; impt when membs leave ER and are incorporated into Golgi

8

transferred selectively from non-cytosolic luminal side to cytosolic monolayer

phospholipids, phosphatidylserine, phosphatidylethanolamine; so phosphatidylecholine and sphingomyelin are concentrated on extracellular side

9

phospholipids and glycolipids are distributed

asymmetrically in PM lipid bilayer

10

sugar groups

glycolipids have them

11

concentrate in extracellular side of monolayer

phosphatidylcholine and sphingomyelin

12

equal distribution in both monolayers

proteins embedded w specific orientation crucial for their function

13

the phospholipids

biosynthesis depends on synthesis of DAG to which a head group is added

14

phosphotidylothanolamine

phospholipid; asym dis btwn memb leaflets is disrupted when blood flow to the heart is restricted and memb is disrupted

15

phosphotidylothanolamine's role in section of VLDLs by liver

degraded to triglycerides , cholesterol, and apolipoproteins and released into blood raising fat levels

16

phosphatidylethanolamine

propagates infectious prions w/o assistance of proteins or NAs

17

blood clotting + phosphatidylethanolamine

increases rate of thrombin formation by promoting binding to factor V and factor X which catalyze formation of thrombin from prothrombin

18

phosphatidylserine

attraction signals, bridging mols, and danger signals are involved in the PS dependent clearance of apoptotic and necrotic cells; prevention of PS dep. clearance of apoptotic tumor cells by macrophages foster uptake and presentation of cancer antigens via MHC2 by dendritic cells and thereby induces specific anti-humor immunity; tumor microvesicles are often rich in PS and thereby contribute to tumor escape mechanisms

19

cell physiology of phosphatidylserine

PS rich microvessels (used in apoptosis and necrosis) evade normal immune sys; PS promotes tolerance and prevents local and systemic immune activation; externalized function of PS is dominant and evolutionary conserved immune suppressive signal to prevent organism from initiating and over activating immune sys

20

pathophysiology of phosphatidylserine

mechanism has been hijacked by certain pathogens like viruses, microorganisms and parasites facilitating infecting; PS found desregulated in tumor microenvironment; expression of asymmetrical PS externalization by tumor cells antagonzies the development of tumor immunity and acts as cancer immunosuppressive (therapy?)

21

phosphatidylcholines

member of lecithin group of yellow brownish fatty substances in animal and plant tissues but absent in membranes of most bacteria including E Coli; plays role in membrane mediated cell signaling and activation of signaling enzymes as important source of DAG

22

dipalmitoyl phosphatidylcholine (aka lecithin)

major component of pulmonary surfactant and often used in the (lecithin sphingomyelin) ration to calculate fetal lung maturity

23

sphingomyelin

type of sphingolipid found in animal cell membranes esp in membranous myelin sheath which surrounds some nerve cell axons

24

Niemann-Pick disease (types A and B)

caused by deficiency in the enzyme sphingomyelinase (used in sphingolipid metabolism) causes accumulation of sphingomyelin in spleen, liver, lungs, bone marrow, and brain causing irreversible neurological damage

25

cholesterol stiffens cell membs

fluidity modulated by sterol cholesterol; fills spaces btwn phospholipid mols left by kinks in unsat hydrocarbon tails stiffens bilayer more rigid less fluid (> VWFs); allows memb to get equilibrium btwn fluidity and rigidity

26

membranes keep orientation during transfer btwn cell compartments

transported via budding + fusion; assembled through ER + transported by budding + fusion to Golgi; budding from Golgi results in fusion w PM ensures cytosolic side of bilayer remains facing cytosol w embedded proteins in correct oreintation

27

plasma membrane protein: transporter

Na+ pump pumps Na+ out of cells and K+ in

28

ion channels (PM protein)

K+ leak channel allows K+ ions to leave cells influencing excitability

29

anchors (PM protein)

integrins ink intracellular actin filaments to extracellular matrix proteins

30

receptors (PM protein)

platelet derived growth factor (PDGF) receptor binds PDGF to get signals causing cell to grow and divide

31

enzymes (PM protein)

adenylyl cyclase catalyzes production of cyclic AMP in response to extracellular signals

32

transmembrane protein

hydrophobic w/i bilayer philic exposed to ECM and cytosol

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monolayer associated alpha helix protein

anchored to cytosolic side by amphipathic alpha helix

34

lipid linked protein

attached via one or more covalently attached lipid groups

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protein attached protein

held by interaction w other memb proteins

36

backbone of PP chain

polar covalent (hydrophilic); atom on either side of PBs carry pos/neg charges; charges allow H bonds to form in alpha helix formation; PPs fold into helix orientation of phobic side protects H bonded philic center as protein spans PM

37

transmembrane hydrophilic pore

formed by multiple alpha helices

38

aquaporin

5 transmembrane alpha helices form water filled channel across lipid bilayer; phobic AA side chains on 1 side of helix contact memb phobic H carbon chains (lipids); philic side on opposite side of helices form water filled pore

39

beta barrel

more rigid than alpha helix for aquaporin channels that form large water filled pores in mitochondria and bacterial membrane; inside selects for mols such as water allowing them to flow through to exclusion of other mols such as ion/ionic; narrow channel disrupts water H bonds as water mols move through in single file

40

osmosis and aquaporin

water (polar + uncharged) is small enough to move slowly across PM via osmosis; aquaporins aid in rapid facil. diffusion of water: RBCs have 2x10(5) copies per cell

41

AQP2 aquaporin

aids in water absorption cross renal cell

42

nephrogenic diabetes

loss/dysfunction

43

spectrin (protein) meshwork

forms cell cortex in human RBCs

44

cell membrane alone

thin and fragile

45

cortex of actin/spectrin

strengthens cell membrane; long thing flexible rob meshwork attached via proteins to PM

46

cell's cortex in RBCs

main component is actin/spectrin meshwork which can be broken + reformed = dynamic instability; genetic abnormality = fragile RBCs and amenia

47

PM proteins that move laterally in bilayer

seen in mouse-human hybrid cells; watch movement of mice + human PM proteins labelled w rhodamine and fluorescein respectively by 30 mins proteins are evenly spread

48

lateral mobility of PM proteins restricted by

(1) tethered to cell cortex (e.g. actins via integrins) (2) tethered ECM outside the cell (e.g. integrins and ECM) (3) bonded to other proteins on surface of another cell (e.g. claudins + occludins result in formation of tight junctional strands providing direct link actin ctoskeleton) (4) restricted to particular membrane domain by diffusion barrier (black bars)

49

membrane proteins restritcted to specific domain

of PM of epithelial cell in the gut

50

transport protein in gut

involved in uptake of nutrients from gut is confined to apical surface (faces gut content)

51

transport proteins of solutes

out of epithelia cells into tissue and bloodstream must be confined to basal and basolateral surfaces maintained by a tight unction creating a seal

52

eukaryotic cells coated w sugars

most mem proteins are oligosaccharide linked (glycoproteins); others w long polysach chains attached (proteoglycans); lipids in outer layer of PM have sugars covalently attached (glycolipids)

53

glycocalyx

protects cell surface from mechanical damage; slimy surface so cells (e.g.neutrophils) can squeeze through; stops blood cells sticking to each other + helps in cell to cell recognition