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VP Exam 2 > Cell bio- membrane > Flashcards

Cell bio- membrane Flashcards

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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
Three types of connective tissue in animals and their type of ECM
- bone tissue= collagen fibers and bone mineral - loose connective tissue= reticular fibers and ground substance - blood= ECM is blood plasma
26
how are macromolecules in the ECM produced?
locally by cells in the matrix and secreted via exocytosis
27
What are the three major classes of macromolecules in the ECM?
glycosaminoglycans (GAGs) fibrous proteins non-collagen fibrous proteins
28
Glycosaminoglycans
eg) cartilage large and highly charged polysaccharides proteoglycans when linked to proteins
29
fibrous proteins
collagen | eg) skin and bone
30
non-collagen fibrous proteins
glycoprotiens | eg) elastin, fibronectin, laminin
31
collagen
fibrous, long, stiff triple-stranded helical proteins rich in proline, glycine and glycosylated
32
Two types of fibril-forming collagen and what tissues they are found in
type 1= bone, skin, tendon, ligaments, cornea, internal organs type 3- skin, blood, internal organs
33
elastin
gives tissues elasticity hydrophobic protein rich in proline and glycine (not glycosylated) skin, blood vessels, lungs
34
glycoproteins
have multiple domains with specific binding sites for other matrix macromolecules and for receptors of the cell surface
35
Basal lamina (basement membrane)
specialized form of ECM thin, flexible, touch essential component of all epithelia
36
laminin
primary organizer of the sheet structure of the basal lamina | composed of three long polypeptide chains held together by disulfide bonds
37
intigrins
link the cytoskeleton wiht the ECM | transmembrane cell adhesion proteins= matrix receptors
38
Cell junction
multiprotein complexes that provide contact between neighboring cells or between a cell and the extracellular matrix
39
functions of a cell junction (5)
- 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
What two type of tissues are cell junctions more abundant?
``` epithelial tissues (lining of gut or skin) connective tissues (bone or tendon) ```
41
what do cell-cell junctions attach?
direct attachments between cells
42
what do cell-matrix junctions attach?
cytoskeletal filaments are anchored and linked to the basal lamina
43
what are the three types of cell-cell junctions?
1. tight junctions (occluding junctions) 2. cell-cell anchoring junctions 3. gap junctions (communicating junctions)
44
what are the two types of cell-cell anchoring junctions?
adherens | desmosomes
45
what is the type of cell-matrix junction?
cell-matrix anchoring junction
46
what are the two types of cell-matrix anchoring junction?
actin linked | hemidesmosomes
47
What makes up the junctional complex?
tight junction | cell-cell anchoring junctions" adherens and desmosomes
48
tight junction
seal gap between apithelial cells impermeable to macromolecules permeable to ions and small molecules
49
where are tight junctions located?
most apical location of epithelial cells (lining of intestinal mucosa, bladder)
50
What are the two proteins that make up tight junctions and what to they make?
cloudin and occuldin | make sealing strands to hold adjacent plasma membranes tocether
51
what two diseases are associated with tight junctions malfunctioning?
Celiac disease | Crohn's disease
52
cell-cell anchoring junctions
form strong, membrane-spanning structures that are tethered inside the cell to filaments of the cytoskeleton
53
Where are cell-cell anchoring junctions located?
widely distributed. mostly in tissues that are subject to severe mechanical stress (heart, muscle, epidermis)
54
what is a protein used in cell-cell anchoring junctions?
cadherins- calcium-dependent adhesion
55
adherens junction: cell-cell anchorinig junction
"adhesion belt" connects actin filament bundle in once cell with another= provides anchorage site for cytockeleton helps model shape of multicellular structures
56
where are asherens junctions located?
more basal than tight junction guides organization of developing tissues (construction of vertebrae nervous system) found in epithelial cells, cardiac muscle, fibroblasts
57
Desmosome: cell-cell anchoring juncitons
connects intermediate filaments in one cell to another provide anchorage site for cytoskeleton links with intermediate filaments provides mechanical strength
58
where are desmosome junctions located?
in tissues that suffer a lot of stress/stretch | skin, intestines, stomach, bladder
59
Gap junctions
allows passage of small water-soluble molecules from cell to cell without having to pass through pl (ions, glucose) narrow gap
60
where are gap junctions located?
tissues containing electrically excitable cells (cardiac muscle, connective tissue, intestines, epithelial tissue, neurons)
61
cell-matrix anchoring junctions
depend on integrins | activated by extracellular matrix ligands or intracellular activator proteins
62
what are the 2 functions of cell-matrix anchoring junctions?
produces intracellular signals that can influence cell behavior (proliferation, survival, polarity and migration) sense and respond to mechanical forces acting across the junction
63
actin-linked cell matrix junction
"focal adhesion" anchors actin filaments in cell to extracellular matrix can be small and transient or large and durable
64
hemidesmosome: cell-matrix junction
anchor intermediate filaments in a cell to the extracellular matrix use integrins
65
where are hemidesmosomes located?
epithelial cells connecting the basal face of the cell to basal lamina

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