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VP Exam 2 > Cell bio- membrane > Flashcards

Cell bio- membrane Flashcards

1
Q

7 organelles with a membrane

A 
plasma
nuclear (inner and outer)
ER
Golgi
Mitochondria (inner and outer)
Peroxisomes 
lysosomes
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2
Q

What are the three main lipids in a membrane?

A

phospholipids
sphingolipids
cholesterol

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3
Q

What are the 6 components of a membrane?

A 
lipids (phospholipids, glycolipids)
proteins (integral, peripheral)
carbs
water
divalent cations
cholesterol
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4
Q

What is the difference between prokaryotic and eukaryotic lipid bilayer?

A

bacteria are composed of one main type of phospholipid and contain no cholesterol
Eukaryotes are varied and contain a large amount of cholesterol and a mixture of different phospholipids

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5
Q

amphipathic

A

have hydrophobic polar end and one hydrophobic nonpolar end

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6
Q

what are the four parts of a phospholipid molecule?

A

choline
phosphate
glycerol
hydrocarbon chain

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7
Q

what are the two ways lipid molecules assemble?

A

spherical micelles

bimolecular sheets- bilayers

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8
Q

is the open formation or the closed formation of a phospholipid bilayer more energetically favorable?

A

closes structure

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9
Q

what are the four major phospholipids in the plasma membrane of mammalian cells?

A

phosphatidylcholine
phosphatidylethanoalmine
phosphatidylserine
sphingomyelin

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10
Q

which major phospholipid has a net negative charge?

A

phosphatidylserine

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11
Q

movement of phospholipids in bilayer- transversal diffusion

A

flip-flop
moves to a different layer (lipid on bottom layer switches with one on top layer
rare

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12
Q

movement of phospholipids in bilayer- lateral diffusion

A

happens readily and rabidly

lipids of same layer switch with one another

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13
Q

What does the fluidity of a lipid bilayer depend on?

A

composition (lipid composition and cholesterol content) and temperature

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14
Q

phase transition

A

change of a lipid bilayer from a liquid state to a rigid crystalline state (gel)

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15
Q

How do cis-double bonds in the hydrocarbon chains affect the membrane structure?

A

make it more difficult to pack the chains together (and to freeze)
more spread apart= thinner membrane

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16
Q

how does a shorter chain affect the fluidity of the membrane?

A

reduces the tendency of hydrocarbon tails to interact with one another
membrane remains fluid at lower temps

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17
Q

how does cholesterol affect the membrane?

A

improve permeability-barrier properties
stabilize the hydrocarbon chains by orienting their hydroxyl groups with polar heads of phospholipid molecules
inhibits phase transitions

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18
Q

what type of structures do saturated fatty acids form?

A

parachrystaline structures

less space between tails

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19
Q

what type of structures do unsaturated fatty acids form?

A

formation of kinks

more space between tails

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20
Q

what is the extracellular matrix?

A

a collection of extracellular molecules secreted by cells

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21
Q

what is the function of ECM? (4)

A

structural and bichemical support to surrounding cells
cell adhesion
cell-cell communicaon
differentiation

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22
Q

What do animal ECM include? (2)

A

intersitial matrix

basement membrane

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23
Q

intersitial matrix

A

present between different animal cells in intercellular space
gels of polysaccharides and fibrous proteins fill intercellular spaces= act as compression buffer

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24
Q

basement membranes

A

sheet-like depositions of ECM with epithelial cells

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25
Q

Three types of connective tissue in animals and their type of ECM

A
  • bone tissue= collagen fibers and bone mineral
  • loose connective tissue= reticular fibers and ground substance
  • blood= ECM is blood plasma
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26
Q

how are macromolecules in the ECM produced?

A

locally by cells in the matrix and secreted via exocytosis

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27
Q

What are the three major classes of macromolecules in the ECM?

A

glycosaminoglycans (GAGs)
fibrous proteins
non-collagen fibrous proteins

28
Q

Glycosaminoglycans

A

eg) cartilage
large and highly charged polysaccharides
proteoglycans when linked to proteins

29
Q

fibrous proteins

A

collagen

eg) skin and bone

30
Q

non-collagen fibrous proteins

A

glycoprotiens

eg) elastin, fibronectin, laminin

31
Q

collagen

A

fibrous, long, stiff
triple-stranded helical proteins
rich in proline, glycine and glycosylated

32
Q

Two types of fibril-forming collagen and what tissues they are found in

A

type 1= bone, skin, tendon, ligaments, cornea, internal organs
type 3- skin, blood, internal organs

33
Q

elastin

A

gives tissues elasticity
hydrophobic protein rich in proline and glycine (not glycosylated)
skin, blood vessels, lungs

34
Q

glycoproteins

A

have multiple domains with specific binding sites for other matrix macromolecules and for receptors of the cell surface

35
Q

Basal lamina (basement membrane)

A

specialized form of ECM
thin, flexible, touch
essential component of all epithelia

36
Q

laminin

A

primary organizer of the sheet structure of the basal lamina

composed of three long polypeptide chains held together by disulfide bonds

37
Q

intigrins

A

link the cytoskeleton wiht the ECM

transmembrane cell adhesion proteins= matrix receptors

38
Q

Cell junction

A

multiprotein complexes that provide contact between neighboring cells or between a cell and the extracellular matrix

39
Q

functions of a cell junction (5)

A
  • bind cells to one another
  • reduce stress places upon cells
  • build up the paracellular barrier of epithelia
  • control of paracellular transport
  • enable communication between neighboring cells
40
Q

What two type of tissues are cell junctions more abundant?

A 
epithelial tissues (lining of gut or skin)
connective tissues (bone or tendon)
41
Q

what do cell-cell junctions attach?

A

direct attachments between cells

42
Q

what do cell-matrix junctions attach?

A

cytoskeletal filaments are anchored and linked to the basal lamina

43
Q

what are the three types of cell-cell junctions?

A
  1. tight junctions (occluding junctions)
  2. cell-cell anchoring junctions
  3. gap junctions (communicating junctions)
44
Q

what are the two types of cell-cell anchoring junctions?

A

adherens

desmosomes

45
Q

what is the type of cell-matrix junction?

A

cell-matrix anchoring junction

46
Q

what are the two types of cell-matrix anchoring junction?

A

actin linked

hemidesmosomes

47
Q

What makes up the junctional complex?

A

tight junction

cell-cell anchoring junctions” adherens and desmosomes

48
Q

tight junction

A

seal gap between apithelial cells
impermeable to macromolecules
permeable to ions and small molecules

49
Q

where are tight junctions located?

A

most apical location of epithelial cells (lining of intestinal mucosa, bladder)

50
Q

What are the two proteins that make up tight junctions and what to they make?

A

cloudin and occuldin

make sealing strands to hold adjacent plasma membranes tocether

51
Q

what two diseases are associated with tight junctions malfunctioning?

A

Celiac disease

Crohn’s disease

52
Q

cell-cell anchoring junctions

A

form strong, membrane-spanning structures that are tethered inside the cell to filaments of the cytoskeleton

53
Q

Where are cell-cell anchoring junctions located?

A

widely distributed. mostly in tissues that are subject to severe mechanical stress
(heart, muscle, epidermis)

54
Q

what is a protein used in cell-cell anchoring junctions?

A

cadherins- calcium-dependent adhesion

55
Q

adherens junction: cell-cell anchorinig junction

A

“adhesion belt”
connects actin filament bundle in once cell with another= provides anchorage site for cytockeleton
helps model shape of multicellular structures

56
Q

where are asherens junctions located?

A

more basal than tight junction
guides organization of developing tissues (construction of vertebrae nervous system)
found in epithelial cells, cardiac muscle, fibroblasts

57
Q

Desmosome: cell-cell anchoring juncitons

A

connects intermediate filaments in one cell to another
provide anchorage site for cytoskeleton
links with intermediate filaments
provides mechanical strength

58
Q

where are desmosome junctions located?

A

in tissues that suffer a lot of stress/stretch

skin, intestines, stomach, bladder

59
Q

Gap junctions

A

allows passage of small water-soluble molecules from cell to cell without having to pass through pl (ions, glucose)
narrow gap

60
Q

where are gap junctions located?

A

tissues containing electrically excitable cells (cardiac muscle, connective tissue, intestines, epithelial tissue, neurons)

61
Q

cell-matrix anchoring junctions

A

depend on integrins

activated by extracellular matrix ligands or intracellular activator proteins

62
Q

what are the 2 functions of cell-matrix anchoring junctions?

A

produces intracellular signals that can influence cell behavior (proliferation, survival, polarity and migration)
sense and respond to mechanical forces acting across the junction

63
Q

actin-linked cell matrix junction

A

“focal adhesion”
anchors actin filaments in cell to extracellular matrix
can be small and transient or large and durable

64
Q

hemidesmosome: cell-matrix junction

A

anchor intermediate filaments in a cell to the extracellular matrix
use integrins

65
Q

where are hemidesmosomes located?

A

epithelial cells connecting the basal face of the cell to basal lamina

VP Exam 2 (10 decks)

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