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Cell Membrane Flashcards

1
Q

The plasma membrane and cytoplasmic membrane serve as attachment surface for what?

A

Cytoskeleton and extracellular structures

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2
Q

The compartmentalization of the cell membrane allows separation of antiparallel processes, allowing anabolic and catabolic processes to be held in separate compartments to avoid competition for substrates. What is an example of this?

A

Fatty acid synthesis in cytosol and fatty acid oxidation in mitochondria.

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3
Q

The compartmentalization of the cell membrane allows separation of similar reactions serving different purposes. What is an example of this?

A

Fatty acid oxidation occurring in the mitochondria for energy production but occurring in the peroxisomes for heat production.

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4
Q

The compartmentalization of the cell membrane allows for coordination of different reactions which involve the same pathway for energy efficiency. What is an example of this?

A

TCA and ETC are the central point of energy metabolism in cells and are both located in the mitochondria.

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5
Q

The following are properties of cell membranes, EXCEPT:
A) Separates cellular interior and exterior
B) Exchanging information w/ environment
C) Non-selective barriers
D) Get info about metabolic status
E) Membranes are extremely dynamic

A

C) Non-selective barriers
The rest are true, but cell membranes have selective barriers allowing for transport of molecules into and out of the cell.

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6
Q

True or False
Membrane fusion and fission ultimately cause damage to the cell membrane.

A

False

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7
Q

Transport vesicles from the ER fusing with the Golgi apparatus is an example of what?

A

Membrane fusion

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8
Q

Formation of vesicles by the ER/GA to transport lipids and proteins to other organelles and to the cell membrane, is an example of what?

A

Membrane fission

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9
Q

This process involves splitting of a membrane into 2 parts.

A

Fission

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10
Q

This process involves 2 separate lipid bilayers merging to become one.

A

Fusion

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11
Q

True or False
Fission and Fusion involve membrane reorganization without loss of continuity

A

True

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12
Q

What are 3 lipid components of the cell membrane?

A

Phospholipids, sterol and glycolipids

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13
Q

What are the two types of proteins in cell membranes?

A

Transmembrane and peripheral

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14
Q

What are the components of the cell membrane?

A

Lipids
Proteins
Carbs
Water
Divalent cations

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15
Q

Most membrane proteins are _____________ proteins and mediate many functions such as ______ and ________ of reactions.

A

transmembrane, transport and catalysis

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16
Q

_________ _______ are targets of over 50% of all modern medicinal drugs

A

Membrane Proteins

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17
Q

Numerous different _______ are necessary for proper cell function and interaction

A

Proteins

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18
Q

True or False
The lipid bilayer is permeable to most polar molecules

A

False
The lipid bilayer is relatively impermeable to most water-soluble (polar) molecules

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19
Q

What are the most abundant membrane lipids?

A

Phospholipids

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20
Q

True or False
All lipid molecules in cell membranes are amphipathic

A

True

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21
Q

Explain the general structure of the lipid bilayer

A

Thin film of lipid and protein molecules, held together mainly by noncovalent interactions.

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22
Q

All cell membranes share a characteristic _______ appearance, meaning the plasma membrane appears as three layers.

A

Trilaminar

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23
Q

What are eukaryotic cell membranes composed of?

A

Mixtures of different phospholipids and large amounts of cholesterol

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24
Q

True or False
Prokaryotic cell membranes are composed of many types of phospholipids

A

False
Prokaryotic cell membranes are made up of one main phospholipid

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25
What type of molecules dissolve readily in water and form either favorable electrostatic interactions or hydrogen bonds with water molecules?
Hydrophilic
26
What type of molecules are insoluble in water due to uncharged, non-polar atoms, and are therefore unable to form energetically favorable interactions with water molecules?
Hydrophobic
27
What two ways can lipid molecules assemble?
Spherical micelles Bilayers (biomolecular sheets)
28
What do lipids spontaneously form in aqueous environments?
Micelles or bilayers
29
What provides the bilayer's self-healing property?
It's ability to become a closed structure where all free edges are avoided by closing in on itself.
30
What microscopy method is used to study the cell membrane's internal structures?
Freeze-fracture technique
31
What two things do structure and flexibility of the lipid bilayer depend on?
Lipids composition Changes with temperature
32
Intra and extra-cellular structures consisting of liquid enclosed by a lipid bilayer
Vesicles
33
Vesicles form naturally during...
Secretion (exocytosis) Uptake (endocytosis) Membrane transport
34
Bilayers as closed spherical vesicles
Liposomes
35
Planar bilayers, formed across a hole in a partition between two aqueous environments
Black membrane
36
What are commonly used to measure the permeability properties of synthetic membranes?
Black membranes
37
What are commonly used as model membranes in experimental studies?
Liposomes
38
True or False Around 1970 researches first recognized that individual lipid molecules could not diffuse freely within lipid bilayers
False They CAN diffuse freely within lipid bilayers
39
What do synthetic lipid bilayers form when in solution?
Liposomes
40
What form of phospholipid movement is rarely seen unless catalyzed due to the difficulty of the movement?
Flip-Flop (Transversal diffusion)
41
What type of diffusion is Flip Flop movement?
Transversal
42
What type of diffusion happens readily and rapidly in the plane?
Lateral diffusion
43
Special transporter proteins that move phospholipids and other lipids in the membrane, associated with the catalysis of transbilayer movement of lipids
Flippases Floppases Scamblases
44
What did fluorescence microscopy show concerning lateral diffusion?
It showed the fusion of two different membranes in which the result was a mix of both proteins.
45
The change of a lipid bilayer from a liquid state to a 2D rigid crystalline state at a characteristic temperature
Membrane Phase Transition
46
Lipid bilayer is stabilized by __________ interactions between lipids fatty acid chains
Hydrophobic
47
What three things do fluidity depend on?
Phospholipid content (FA length/saturation) Cholesterol content Temperature
48
What is the most ideal temperature for fluidity?
20-40C / 68-104F
49
At low temperatures, there is less lipid movement, therefore the bilayer is in _________ state (more rigid)
paracrystalline
50
What FA's make it more difficult to pack the hydrocarbon chains together?
Unsaturated FA's
51
What FA properties would result in a lower melting point?
More Unsaturated FA's --> Short-chain FA --> Thinner membrane
52
What kind of structure do saturated FAs tend to form?
Paracrystalline
53
If there is increased amount of saturated FAs in a structure what would be the result on the melting point?
Melting point would be higher
54
What causes the "kinks" in unsaturated FAs?
Cis-double bonds
55
What inhibits paracrystalline conformation?
Unsaturated FAs / cis-double bonds
56
If there is a higher concentration of unsaturated FAs what would be the effect on the melting point?
Melting point would be lower
57
Cholesterol can inhibit or delay __________ _________
Phase transitions
58
What plasma membranes contain very large amounts of cholesterol?
Eukaryotic plasma membranes
59
How does cholesterol improve the impermeability-barrier properties of the lipid bilayer?
They orient themselves with their hydroxyl groups close to the polar heads of the phospholipids The rigid steroid ring supports the hydrocarbon chains
60
What happens to cholesterol at high temperatures?
Keeps the membrane more stable, stiffening the bilayer, making it less fluid and less permeable
61
What happens to cholesterol at low temperatures?
Acts as antifreeze to help the membrane remain more fluid by preventing fatty acid tails from interacting and clumping
62
What is the ECM of bone tissue?
Collagen fibers and bone mineral
63
What is the ECM of loose connective tissue?
Reticular fibers and ground substance
64
What is the ECM of blood?
Blood plasma
65
Three common functions of the ECM
Cell adhesion Cell to Cell communication Differentiation
66
What produces and secretes ECM?
Fibroblasts
67
What are the fibroblasts in connective tissue?
Collagen fibers
68
What can fibroblasts differentiate into and what are they associated with?
Chondroblasts - cartilage Osteoblasts - bone tissue Myofibroblasts - muscle tissue
69
Large and highly charged polysaccharides
Glycosaminoglycans (GAGs)
70
What make up proteoglycans?
GAG + Protein
71
What makes up ground substance?
GAG + Proteoglycan
72
Amourphous gelatinous material that fills in the space between fibers and cells
Ground Substance
73
What are the major classes of marcomolecules in the ECM?
GAGs Fibrous proteins Non-collagen fibrous proteins
74
What are the structural proteins?
Fibrous collagen and elastin
75
What are the adhesive proteins?
Laminin and fibronectin
76
Fibrous, long, stiff, triple-stranded helical proteins that form fibrils
Collagen
77
Collagen are rich in what amino acids?
Proline and Glycine
78
True or false The fibrils in collagen are glycosylated
True
79
Where does glycosylation primarily occur?
Endoplasmic reticulum and Golgi apparatus
80
What is protein glycosylation?
It is a post-translational modification where sugar molecules are added to the protein
81
What types of collagen have a polymerized form as fibril?
Type I and Type III
82
What type of collagen is distributed in the bone, skin, tendons, ligaments, cornea, and internal organs- accounting for 90% of body collagen?
Collagen Type I
83
What type of collagen is distributed in the skin, blood vessels and internal organs?
Type III
84
What type of collagen is network forming and is distributed in the basal laminae?
Type IV
85
What are the fiber forming (fibrillar) types of collagen?
Type I and Type III
86
Hydrophobic protein rich in proline and glycine but is NOT glycosylated
Elastin
87
What kind of bonds are found in elastin?
Covalent bonds to generate a cross-linked network
88
Multifunctional adhesive glycoprotein that aids in tissue repair, regulating cell attachment and motility, and in embyrogenesis
Fibronectin
89
Specialized form of ECM that is an essential component of all epithelia and is thin, flexible, and tough
Basal lamina
90
What is the primary organizer of the sheet structure of the basal lamina?
Laminin
91
Composed of three long poly-peptide chains and held together by disulfide bonds
Laminin
92
Family of transmembrane proteins synthesized in several types of cells
Integrins
93

Cell Bio (8 decks)

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