Chapter 11 - Membrane Structure Flashcards
1
Q
Which cells have internal membranes
A
Eukaryotic cells
2
Q
Receptor proteins are where
A
Plasma membrane
3
Q
Receptors proteins acts as what and what is the function
A
Sensors that enable the cell to receive information about changes in its environment and respond to them
4
Q
If a cell is to survive and grow, _________ must pass inward cross the plasma membrane, _________ must pass out by highly selective channels and pump proteins.
A
Nutrients, waste products
5
Q
Internal membranes functions
A
Surround organelles
6
Q
Nucleus, mitochondria, and chloroplast are enclosed by
A
Two membranes; outer and inner
7
Q
The cell membrane is made up of
A
Lipids and proteins
8
Q
Lipid bilayer is made up of
A
Lipids are arranged into closely apposed sheets
9
Q
Each membrane lipid is composed of what
A
Hydrophilic head and one or two hydrophobic tails
10
Q
What is the most abundant lipids in cell membrane
A
Phospholipids
11
Q
What is the most common phospholipid in cell membrane
A
Phosphatidycholine
12
Q
What are hydrophobic tails made of
A
Fatty acids
13
Q
Describe saturated fatty acids bonds
A
Has no double bonds between their carbon atoms
14
Q
Describe Unsaturated fatty acids bond
A
Have 1 or more double bonds between their carbon atoms
15
Q
Monounsaturated bonds fatty acids
A
Have 1 double bonds
16
Q
Polyunsaturated fatty acids
A
Have 2 or more double bonds
17
Q
What molecules dissolves in water
A
Hydrophilic molecules
18
Q
Double bonds does what to the tails
A
Make it bend
19
Q
Amphipathic
A
Because they have both hydrophilic and hydrophobic properties
20
Q
OH is nonpolar or polar
A
Polar
21
Q
Cholesterol lacks
A
Fatty acids
22
Q
Molecules that are insoluble in water
A
Hydrophobic molecules
23
Q
Hydrophobic exclusion
A
When hydrophobic molecules exclude themselves from water staying together
24
Q
Triacylglcerols or triglycerides
A
Stores energy
25
What are main constituents of animal fats and plant oils, entirely hydrophobic
Triacylglycerols
26
Cis unsaturated bonds
Hydrogens are on the same side of double bond
27
Trans unsaturated bonds
Hydrogen bonds on the opposite sides of double bonds
28
What fats are usually solid at room temperature
Saturated
29
Why are saturated bonds solid at room temp
H-C tails lack double bonds, causing them to pack closely together
30
Example of saturated fats
Butter
31
What is usually liquid at room temp
Unsaturated fats
32
Why is unsaturated fats liquid at room temps
H-C tails have double bonds, preventing them from packing closely together
33
Example of unsaturated
Olive oil
34
How do you get from oil to solid fat
Hydrogenation
35
Hydrogenation
Adding H atoms
36
Both plasma membrane and internal membranes are made up of
Lipid bilayers
37
What happens if membrane components can not move what happen
Cell can not function properly
38
What happens when phospholipids close in on themselves
Form sealed compartments
39
Why when the phospholipid closed, it is stable
It avoids the exposure because it avoids the exposure of hydrophobic hydrocarbon tails to water, which would be energetically unfavorable
40
The fluidity of lipid bilayer can be studied using what
Synthetic lipid bilayer free of proteins
41
Liposome
Closed spherical vesicles that form when pure phospholipids are added to water
42
Noncytosolic monolayer
Faces the extra cellular fluid or lumen of the organelle or vesicle
43
Cytotoxic monolayer or leaflet
Faces the cytosol
44
What happens to the fluidity of the bilayers when temperature goes up
Goes up
45
The smaller the length of hydrocarbon tails what happens to the number of double bonds
Higher number of double bonds
46
How do double bonds and fluidity correlate
More double bonds, higher fluidity
47
Cholesterol is...
A lipid (steroid)
48
Cholesterol is found where
Animal cells membranes and internal membranes
49
What stiffens the bilayer, making it more rigid and less permeable
Cholesterol
50
Enzymes scramblases
Randomly transfer phospholipids from one monolayer to other, allowing membrane to grow evenly
51
New phospholipids are made by enzymes bound from where
Part of the ER membrane that faces the cytosol
52
Flippases found
Golgi apparatusq
53
Flippases
Phospholipid handling enzymes found in the membrane of the golgi
54
Flippases remove
Specific phospholipids from the non cytosol is monolayer and flip them to the cytosol is side
55
Flippases symmetrical of asymmetrical
Asymmetrical
56
Scramblases symmetrical or asymmetrical
Symmetrical
57
Scramblases require atp
No
58
Flippases require atp
Yes
59
Scramblases movement
Bidirectional
60
Flippases movement
Undirectional
61
Glycolipids mainly located in and found in which layer
Plasma membrane; noncytosolic half
62
Where does glycoproteins acquire their sugar groups
Golgi
63
Glycolipid faces where and not where
Extra cellular fluid and lumen
Not cytosol
64
Most membrane functions are carried out by
Membrane proteins
65
4 different ways in which membrane proteins associate with the lipid bilayer
Transmembrane
Monolayer associate alpha helix
Lipid linked
Protein attached
66
Transmembrane protein
Extend across the bilayer as single alpha helix, multiple alpha helices or b barrel
67
Monolayer associated alpha helix protein
Anchored to cytosol is surface by amphipathic alpha helix
68
Lipid linked protein
Attached to either side of the bilayer solely by covalent attachment to lipid molecule
69
Protein attached
Attached to the membrane only by relatively weak noncovalent interactions with other membrane proteins
70
Which proteins are integral membrane proteins
Transmembrane, mono layered, lipid proteins
71
Integral proteins can be removed by
Disrupting the bilayer with detergents
72
Which proteins are peripheral membrane proteins
Protein attached protein
73
How can peripheral membrane proteins be released
More gently procedures that interfere with protein protein interactions but leave lipid bilayer still intact, treatment with high salt or changing the pH of the solution
74
Peptide bonds are polar or non polar
Polar
75
Some Multiple alpha helices from what
Transmembrane hydrophilic pores
76
Hydrophilic pore
Water filled channel that allows water molecules to pass through hydrophobic region of lipid bilayer
77
Porin proteins made up of what
B barrel
78
Porin protein
Water filled protein in the bacterial membrane and outer membranes of mitochondria and chloroplast
79
Bacteriorhodopsin consist of how many alpha helices
7 transmembrane helices
80
Bacteriorhodopsin acts as
Transporter by pumping H+ protons out of the archaean
81
How can bacteriorhodopsin changes it shape and causes protein to undergo a small series of small confromational changes
Retinal absorbs photon of light
82
Cell cortex
Determines the shape of the cel and mechanical properties of the plasma membrane
83
Spectrin meshwork
Consist of actin filaments and spectrin
84
Spectrin is made out of
Fibrous protein
85
4 ways to restrict lateral mobility of plasma membrane protein
Cell cortex
ECM molecules
Surface proteins
Diffusion barrier
86
Tight junction formed
Junctional proteins
87
What are the sugars role on the cell surface
Absorbs water, gives the cell slimy surface, prevents blood sticking to one another or walls of blood vessels.
Also plays a role in cell to cell recognition and adhesion
88
Oligosaccharides are made up of
3-10 monosaccharides
89
Carbohydrate layer aka
Glycocolyx layer
90
Oligosaccharides are carried by what
Glycolipids and glycoproteins
91
Where are oligosaccharides found
On the extra cellular face of neutrophils
92
Oligosaccharides are recognized by
Lectins
93
Where are lectins found
On the endothelial cells lining the blood vessels at the site of infection
94
Neutrophil
Type of white blood cell that engulfes bacteria by phagocytosis
95
What is important about oligosaccharides
Provide ID tags for cells, which are recognized by immune system and pathogens
96
FRAP (fluorescence recovery after photo bleaching)
Photo bleaching technique used to measure the rate of lateral diffusion of membrane proteins
97
Membrane proteins of interest are tagged with what during the FRAP method
GFP
98
Fluorescent proteins are bleached with what
Bleached using a laser beam
99
The rate of this fluorescence recovery is a direct measure of what
The rate at which surrounding proteins molecules can diffuse within the membrane
100
Detergents
Small amphipathic lipid like molecules that differed from membrane phospholipids by having only single hydrophobic tail
101
SDS (sodium dodecyl sulfate)
Strong ionic detergent that displaces lipid molecules from proteins and also unfolds the proteins
102
Triton X-100
Mild nonionic detergent that solubilizes membrane proteins
103
How do detergents work
Spontaneously aggregate into clusters or micelles in water and they squeeze in between lipids and proteins in the plasma membrane and separate them and keep them in water soluble complexes.
