Chapter 5, Membrane Structure, Synthesis, Transport Flashcards
1
Q
Membrane Structure
A
Two leaflets made of phospholipid bilayers
2
Q
Fluid Mosaic Model
A
- double layer of phospholipids
3
Q
Phospholipids are _________
A
amphipathic
4
Q
Amphipathic means
A
containing partial + and - charges
5
Q
Fatty acid tails are _______
A
nonpolar
6
Q
Phosphate heads are ______
A
polar
7
Q
Each phospholipid bilayer called a
A
leaflet
8
Q
Leaflet on outer cell called
A
extracellular leaflet
9
Q
Leaflet on inside of cell called
A
Cytosolic leaflet
10
Q
Selective Permeability means
A
-polar molecules cannot pass through hydrophobic membrane center
- non molecules can diffuse through the membrane
11
Q
There are ____ embedded into phospholipid bilayer
A
proteins
12
Q
Protein ratio varies from ___-___ times more lipid molecules than protein molecules
A
15-70
13
Q
_____ determine the exact function of cells different membranes
A
proteins
14
Q
_____ do the bulk of the membrane’s work
A
proteins
15
Q
_______ membrane proteins less associated with membrane and are ____ bound to membrane
A
peripheral, loosely
16
Q
Peripheral membranes bound by _____ or _______ bonds
A
hydrogen or ionic
17
Q
Peripheral proteins bound to ___________ proteins also called the _______ __ _______
A
transmembrane proteins, heads of phospholipids
18
Q
Exposed proteins of peripheral proteins are usually _____ for binding
A
polar
19
Q
Because peripheral proteins only occur on 1/2 leaflets, membranes may be ______ with __________ ______
A
asymmetric, different functions
20
Q
_______ proteins are more closely associated with the membrane
A
integral
21
Q
Integral proteins often ____ the membrane
A
span, transverse
22
Q
Exposed portions of integral proteins usually _____ for binding
A
nonpolar
23
Q
Two types of integral proteins
A
- transmembrane
- lipid-anchored
24
Q
Transmembrane proteins transverse the membrane with domains forming ______
A
a-helices (alpha)
25
Regions of alpha proteins occur on ______ ____ of membrane and may be bound to _________
both sides, cytoskeleton
26
Lipid anchored proteins have a lipid _____ attached to the protein
covalently
27
Lipid is inserted into phospholipid bilayer to ______ the protein
anchor
28
Phospholipids in the membrane are... to each other
NOT covalently bound
29
The phospholipids are _________________ within the membrane
free to move
30
Phosophlipid can move from one end of cell to other in...
less than a second
31
______ seconds in a eukaryotic cell
5-10
32
Phospholipids cannot move...
between leaflets
33
Special protein needed to move phospholipids between leaflets using ATP is
Flippase
34
most common phospholipids have an _____ number of carbons
even (18-20 in the tails)
35
Up to 25% of the lipids in animal cell membranes may be ___________
cholesterol
36
The membrane is more fluid if...
there are fewer hydrophobic interactions
37
There will be fewer hydrophobic interactions with... (3)
- shorter hydrocarbon chains
- more unsaturated hydrocarbon chains (more kinks in chain)
- more cholesterol makes it MORE fluid at LOW TEMP
38
Phospholipids cannot flip flop between leaflets because of their _______
polarity
39
membrane ______ can also diffuse/move throughout the membrane
proteins
40
Some proteins exposed to the cytoplasm attach to ______, anchoring them in place
cytoskeleton
41
Carbs in membranes only occur as _______ and __________
- glycolipids
- glycoproteins
42
Carbs in membranes only occur in the _______ leaflet of plasma membrane
exterior (extracellular)
43
Glycoproteins and Glycolipids in plasma membrane can act as ______
antigens, which identify cells of organisms
44
Glycoproteins and Glycolipids in plasma membrane can also label...
proteins with signals for cellular destinations
45
Glycocalyx is a
thick layer of carbs outside plasma membrane
46
Purpose of glycocalyx
shield cell from immune system of other cells
47
Phospholipids are synthesized by the
smooth ER
48
Phospholipids can be spread throughout the Endomembrane System by _______ _________
lateral diffusion
49
Membranes of nucleus, ER, golgi, plasma membrane, mitochondria, and chloroplasts are either _________ ______ or connected by ________
directly connected, connected by vesicles
50
Lipid Exchange proteins can...
extract lipid from one membrane, diffuse through cytoplasm, and insert it into any other membrane
51
The _________ and __________ both synthesize various types of proteins which are transferred to other organelles by lipid exchange proteins
mitochondria, chloroplast
52
Most transmembrane proteins are synthesized in ...
rough ER
53
___________ _________ left in ER membrane as they are synthesized, forming transmembrane proteins
Hydrophobic alpha helices
54
From ER, proteins moved to other membranes by ______
vesicles
55
Glycosylation of proteins occurs in _______ _____ with modifications in the _______
rough ER, golgi
56
Oligosaccharides are synthesized in the...
lumen of the ER, on a dilichol lipid then transferred as unit to R/Side group of acid on proteins
57
The golgi _______ and ______ a lot of proteins
synthesizes and modifies
58
Proteoglycans are a type of
glycoprotein
59
Proteoglycans are often _______ from the cell to help form the ______ ______
secreted, extracellular matrix
60
Biological membranes are ______ ___________ because of their ___________ interior
selectively permeable, hydrophobic
61
Molecules passed through membranes by two types of transport
active, passive
62
two types of passive transport
simple/passive, facilitated diffusion
63
In passive transport..
molecules move down or with concentration gradient
64
Active transport...
molecules move up or against concentration gradient, require ATP
65
Two types of active transport
primary, secondary
66
Passive transport depends on the ______ energy of the solute molecule
kinetic
67
Kinetic energy is...
energy of molecules in motion
68
All molecules are in ________ ________
constant motion
69
Molecules in motion...
tend to evenly distribute themselves with time
70
Simple/passive is ____ movement (from high to low conc.)
net
71
Passive usually occurs for ____ molecules or small _____ molecules
nonpolar, uncharged
72
The molecules diffuse directly through __________ ___________
phospholipid bilayer
73
Primary examples of passive diffusion of molecules moving directly through membrane are diffusion of gases...(3)
oxygen, nitrogen, carbon dioxide
74
Rate of diffusion depends on (4)
- electrical charge
- temperature
- concentration
- molecular size
75
With a high different in concentration, molecules will move...
faster
76
Diffusion over ______ distances is very effective
short
77
_______ molecules can diffuse throughout the cell, ________ molecules needs special means to transport them
nonpolar, polar
78
Facilitated diffusion is _________ transport
passive
79
facilitated diffusion passive because...
still moving from high to low
80
Facilitated diffusion used to move
polar and macromolecules
81
Facilitated diffusion transports using ________
proteins
82
Proteins must be ________ or __________ proteins
channel, carrier/transport
83
Channel proteins are __________ proteins that form channels through membrane through which certain molecules can diffuse
transmembrane
84
Channel proteins may be _____ and only transport when ____ is open
gated, gate
85
______-gated channels open when _____ ______ is bound
ligand, signal molecule (ligand)
86
_____-gated channels open when membrane is....
voltage, depolarized by change in electrical charge across membrane
87
transporter proteins bind to solute usually by a ______ change in protein
conformational (shape)3
88
3 types of transporters are
uniport
symport
antiport
89
Uniport
transports one (same kind) solute molecule in one direction
90
Symport
transports two different kinds of molecules in same direction
91
Antiport
Transports two different kinds in two different directions (one at a time)
92
Primary Active Transport is...(3)
- transport of substance with pump
- against concentration gradient
- with DIRECT expenditure of energy
93
_____ is often energy source used
ATP
94
The __________________ is classic example of Primary AT
Sodium Potassium pump
95
Na/K pump : Pumping two cation at uneven rates results in...
electrical charge across plasma membrane
96
Secondary Active Transport
Uses AT of molecule to drive transport of 2nd molecules AGAINST gradient by using left over ATp
97
Secondary AT is different because...
no ATP EXPENDED DIRECTLY, uses ATP already made, molecule piggy backs and flows against concentration gradient
98
Because of active transport something flowed against its gradient, its imbalanced and wants to equalize, so...
secondary AT uses energy from primary to go against gradient and keep it from equilizing
99
Osmosis is ...
diffusion of water through semipermeable membrane
100
Water sometimes diffuses through special pores in membranes called
aquaporins
101
Aquaporins found in (3)
plant cells, kidney cells, RBC of animals
102
Water molecules pass ____ ___ through the pore, which excludes other molecules
single file
103
Water molecules can also hitchhike, bound to ______ when they pass through pores
cations
104
There are three conditions into which a cell may be placed
Hypotonic
Hypertonic
Isotonic
105
Hypotonic, Hypertonic, Isotonic refer to ______
tonicity
106
Isotonic means
solution has same solute and same water concentration, cell volume DOES NOT change
107
Hypertonic means
Solution has higher solute concentration, lower water concentration
Cell has higher water concentration, so water goes out of cell to equalize, cell looses volume
108
Hypotonic means
Solute has lower solute concentration, higher water concentration
Cell has lower water concentration, water goes into cell, cell gains volume
109
Endocytosis
brings large sized materials into cell using Vesicle formation
110
______ ________ endocytosis uses receptors to concentrate materials before brigning them in
receptor mediated
111
Receptors perfectly fit thing to bring in, so certain number of receptors fill up and then...
that signals cell to bring cargo in
112
After vesicles bring material in, material can fuse with a _____ ________
primary lysosome
113
Macromolecules are digested to _______ before they are transported to the cytoplasm
monomers
114
Exocytosis
discards material from cell using vesicles
115
Exocytosis also add ________ to the plasma membrane
phospholipids
116
_____ is famous for secreting material
golgi
117
cells produce extracellular matrix for ______ and ______
strength and support
118
Multicellular organisms use cell ________ to hold adjacent cells together
junctions
119
Most cell junctions composed of _____
proteins
120
Anchoring junctions made up of
cadherin and integrin
121
Tight junctions made up of
occludin and claudin
122
Gap junctions made up of
connexon
123
Connect to elements of _____ in adjacent cells
cytoskeleton
124
(anchoring junction) cadherin are ___ proteins connected to...
fibrous, actin microfilaments in the cytoplasm
125
Cadherin extends into extracellular matrix where Ca2+ helps to...
bind them together
126
Integrins are composed of... which then bind to...
two subunits, bind to actin microfilaments in cytoplasm
127
In extracellular matrix, integrin binds to ______ which then bind to elements of the matrix such as ____ fibers
fibronectin (wishbone), collagen
128
Tight junctions form ____ between cells
seals
129
Tight junctions (2)
- limit movement of materials through intercellular spaces
- Limit movement of proteins within the membrane
130
Gap junctions form _____ connecting the _____ of two adjacent cells
channels, cytoplasm
131
Gap junction function
allow passage of small ions and small molecules for communication between cells
132
