bio130 exam Flashcards
(145 cards)
1
Q
animal cell specific organelles
A
ECM, lysosome
2
Q
extracellular matrix is
A
specialized material outside of the cell
3
Q
organelles not found in animal cells
A
cell wall, vacuole, chloroplast
4
Q
2 types of vacuole purpose
A
degradation, storage
5
Q
what’s considered in the cytoplasm vs cytosol
A
(cytoplasm) everything in the cell excl. nucleus vs (cytosol) aqueous part of cytoplasm + ribosomes + cytoskeleton
6
Q
main biochemical property of all lipids in the bilayer
A
amphipathic
7
Q
phosphoglycerides are defined by…
A
their glycerol group
8
Q
structure of phosphoglycerides
A
some group, phosphate, glycerol, hydrocarbon tail (saturated or unsaturated)
9
Q
length of phosphoglyceride
A
14-24 carbon atoms
10
Q
kink in unsaturated hydrocarbon tail is caused by
A
C=C cis-double bond
11
Q
liposomes and thier purpose
A
artificial lipid bilayers used to study lipid/membrane protein properties
12
Q
method to manipulate membrane without causing damage?
A
laser tweezers
13
Q
laser tweezers are used in combination with what technique usually
A
live cell imaging
14
Q
possible movement for individual phospholipid
A
lateral diffusion, rotation, flexion, flip-flop
15
Q
which phospholipid movement is the rarest (unfacilitated)
A
flip-flop
16
Q
what affects membrane fluidity
A
temperature, phospholipid composition (saturation, tail length, sterol presence)
17
Q
what sterols are used in animals vs plants to control membrane rigidity
A
animals: mainly cholesterol
plants: plant sterols, some cholesterol
18
Q
max cholesterol:phospholipid ratio
A
1:1
19
Q
increase in sterol means…
A
dec mobility of phospholipid tails, membrane less permeable to polar molecules
20
Q
structure of sterol
A
hydrophilic head group, right planar steroid ring structure, nonpolar hydrocarbon tail
21
Q
scramblase?
A
catalyzes flip flop of random phospholipids from 1 leaflet to another
22
Q
where does scramblase act
A
in the ER
23
Q
why does scramblase act
A
phospholipids are synthesized in the cytosolic leaflet of the ER - flip flopping balances the 2 leaflets out
24
Q
the leaflets of the lipid bilayer are different in that…
A
noncytosolic face vs cytosolic face
25
flippase?
catalyzes flip flop of specific phospholipids to the cytosolic leaflet. can bind cytosolic proteins
26
what does phosphatidylserine do
binds protein kinase C
27
where does flippase act
golgi membrane
28
where is membrane built and sent (pathway)
ER -> golgi -> transport vesicle -> plasma membrane
29
how are glycolipids and glycoproteins formed
adding sugar groups to lipids/proteins on the luminal/noncytosolic face of the Golgi
30
luminal face property (flip flopping)
consistent, no flip flopping (??)
31
types of membrane proteins
integral (transmembrane, monolayer-associated, lipid-linked), peripheral (protein-attached, lipid-attached)
32
integral membrane proteins are
directly attached to the lipid bilayer or attached to a lipid which is inserted into the lipid bilayer
33
how to (destroy lipid bilayer) extract integral membrane proteins
detergenr
34
how can peripheral membrane proteins be bound
bound to other proteins, lipids, non-covalent interactions
35
types of transmembrane proteins
single pass (single alpha helix), multipass (many alpha helices, beta barrel)
36
structure of single alpha helix single pass protein
has a section of 20-30 hydrophobic amino acids
37
transmembrane protein orientation particularities (movement vs phospholipids)
they have specific orientations b/c they can't flip flop (unlike phospholipids)
38
how are membrane proteins identified (techniques)
x-ray crystallography, hydrophobicity plots
39
what does x-ray crystallography do
determines 3D structures
40
what can hydrophobicity plots tell you
segments of 20-30 hydrophobic AAs can span the lipid bilayer as an alpha helix
41
how are proteins anchored onto a cytosolic face (monolayer-associated)
by an amphipathic alpha helix
42
how are GPI anchor lipid linked membrane proteins made
synthesized in ER lumen, ends up on noncytosolic face of cell surface
43
how are fatty acid/prenyl anchored lipid-linked membrane proteins made
cytosolic enzymes add the anchor, direct protein to cytosolic face
44
what do you need to be careful of when destroying and reassembling the membrane
proteins may get put back in the wrong orientation
45
FRAP stands for
fluorescence recovery after photobleaching
46
how does FRAP work
protein fused to GFP/fluorescent antibody, photobleach an area, measure recovery time
47
artificial bilayer permeability
impermeable to most water soluble molecules
48
cell membrane general permeability
molecules can cross via facilitated transport/membrane transport proteins
49
what molecules can diffuse faster across lipid bilayer
more hydrophobic or non-polar molecules
50
rank the following from easiest to cross membrane to hardest: small nonpolar vs uncharged polar vs ions vs large uncharged polar
small nonpolar, small uncharged polar, large uncharged polar, ions
51
what molecules are impermeable to membrane
ions
52
2 main classes of membrane transport proteins
channel, transporter
53
how do channel proteins bind to their transported molecules
bind weakly to transported molecules
54
how does channel protein selectivity work
selected based on size and electric charge of solute
55
channel vs transporter protein (conformation)
channel doesn't change in conformation during transport, transporter changes a lot
56
how does transporter protein selectivity work
solute needs to fit into the binding site
57
types of passive transport
channel-mediated, transporter-mediated (uniport)
58
types of active transport
gradient-driven pumps, ATP-driven pumps (both types of transporters)
59
concentration gradient vs resting membrane potential in strength
concentration gradient is usu larger than resting membrane potential
60
electrochemical gradient =
concentration gradient + membrane potential
61
how are gated ion channels activated
require some signal to open channel
62
what has a role in generating resting membrane potential in animal cells
non-gated ion channels, na+/k+ pump or h+ pump
63
types of gated ion channels
mechanically, ligand (intracellular, extracellular), voltage
64
uniport proteins transport __ solutes w/ [transport method]
transport 1 solute w/ passive transport/down gradient
65
what happens to uniport proteins when EC gradient shifts
transport reverses
66
example of uniport
glucose transporter (GLUT uniporter)
67
types of active transport pumps
gradient-driven, atp-drive, light-driven
68
gradient driven pumps... (how do they work)
1 solute goes down its gradient to generate energy for the 2nd solute going against its gradient
69
types of gradient pumps
symport, antiport
70
example of symporter and how it works
na+ down gradient into cytosol, glucose against gradient
71
example of antiporter and how it works
na+ down gradient into cytosol, h+ against gradient
72
why is moving h+ important
cytosol ph needs to be regulated for enzymes
73
why is moving na+ out of cell important
pumped into cell for gradient-driven pumps, sent back out to extracellular space with na+-k+ pumps
74
types of atp-driven pumps
p-type, abc transporter, v-type proton
75
what's special about p-type pumps
pump is phosphorylated during the pumping cycle
76
what type of pump is na+ k+ pump
p type
77
ratio of na+ and k+ in na+/k+ pump
3 na out, 2 k in
78
___ pump in animals and __ pump in plants (for membrane potential)
na+-k+, h+
79
na+ EC gradient equivalent for plants
h+ EC gradient
80
how does ABC transporter work
uses 2 atp to pump small molecules
81
how does v-type proton pump work
uses atp to pump h+ into organelles to acidify lumen
82
how does f-type atp synthase work
uses h+ gradient to drive synthesis of atp
83
where are v-type proton pumps found
lysosome, plant vacuole
84
where are h-type atp synthases found
mitochondria, chloroplast, bacteria
85
apical, lateral, basal domains are
apical: membrane covering microvillus
lateral: membrane in extracellular fluid in b/w epithelial cells
basal: membrane in extracellular fluid opposite of apical domain
86
where is glucose concentration high (in intestine)
inside epithelial cell
87
basolateral domain
basal + lateral domains
88
proteins involved in glucose control
na+driven glucose symport, na+ k+ pump, passive glucose uniport
89
transcellular transport of glucose requires...
asymmetric distribution of membrane proteins
90
how is asymmetry of membrane proteins in epithelial cells maintained
tight junctions
91
basolateral plasma membrane has what proteins
GLUT2 uniporter, na+ k+ pump
92
membrane potential defn
difference in electrical charge on 2 sides of membrane, from POV of inside of the cell
93
role of k+ leak channels
flow of k+ to extracellular space
94
na+ k+ pump generates ___% of membrane potential
10
95
net ion of na+ k+ pump
1+ ion pumped out (into extracellular space)
96
animal cell resting membrane potential (give range)
-20mV to -200mV
97
cytosol na+, k+, cl- content compared to extracellular space
cytosol: low na+, low cl-, high k+
extracelular space: opp.
98
membrane potential for plants (range)
-120 to -160mV
99
hepotocyte job
help with detox in liver cells
100
how much of the cell is cytosol (volume)
half the cell volume
101
RER vs SER amounts in liver hepatocyte vs pancreatic exocrine cell
RER + SER = ~50%
more SER in hepatocyte
102
there's more membrane ___ in the cell
in the cell (vs around the cell)
103
role of SER
PHOSpholipid synthesis and detoxification
104
role of RER
synthesis of soluble proteins and transmembrane proteins
105
defn of organelle
a discrete structure of a euk cell specialized to carry out a particular function, typically membrane enclosed
106
e.g. non membrane bound organeles
nucleolus, centrosome
107
cytosolic protein
have no signal sequence, default location is the cytosol
108
signal sequence/sorting signal
a specific seq of AA that tells the cell where the protein should go
109
sorting receptor protein
recognize signal sequences and take proteins to their destination
110
post translational sorting
proteins are fully synthesized in the cytosol before sorting
111
post translational sorting destinations and folded or unfolded
nucleus peroxisomes (folded) mitochondria plastids (unfolded)
112
co translational sorting
proteins are sorted during translation which is done in the ER (proteins have an ER signal sequence)
113
signal sequence for nucleus and receptor
nuclear localization signal and nuclear import receptor
114
transcription activators
required in nucleus for euk transcription
115
how are proteins sorted into peroxisomes
imported through a transmembrane protein complex
116
most mitochondria and chloroplasts proteins are...
nuclear-encoded
117
how does the unfolding work for mitochondrial and chloroplast proteins
proteins are unfolded for import by hsp70 proteins
118
property of the ER signal sequence
hydrophobic
119
2 types of proteins entering the ER and where do they end up
soluble proteins (secreted outside of the cell or within lumen of organelle) and transmembrane proteins
120
process of cotranslational translocation for soluble proteins
N-terminal ER signal emerges, SRP recognition and elongation arrest, translocon open, synthesis resumes into ER lumen, signal peptidase cleaves ER signal sequence (sometimes)
121
SRP ribosome complex is made of
SRP receptor + translocon
122
diff b/w translocation for transmembrane protein and soluble protein
transmembrane has hydrophobic stop transfer sequence
123
what is the translocon
protein that lets specific proteins in
124
3 types of ER signal sequences and what is their primary protein structure
N-terminal, hydrophobic start, hydrophobic start (the latter 2 are membrane spanning alpha helix)
125
pathways of the endomembrane system
secretory, endocytic, retrieval
126
what does the secretory pathway involve in endomembrane system
proteins and lipids made in the ER are deliverd to other places in the cell
127
2 types of secretory pathway
constitutive exocytosis pathway, regulated exocytosis pathway
128
constitutive exocytosis pathway occurs only in
all euk cells
129
constitutive exocytosis pathway role
continual delivery of proteins and lipids to plasma membrane and secretion of soluble proteins
130
regulated exocytosis pathway occurs in...
specialized cells
131
regulated exocytosis pathway involved
regulated secretion stored in specialized secretory vesicles, secretion triggered by extracellular signals
132
path of a secreted protein
cytosolic ribosomes, co-translational translocation at ER, moved in transport vesicles to the plasma membrane, secreted
133
golgi apparatus
usually the first stop, receives proteins and lipids from the ER, modifies them, and dispatches them to the
134
where does protein glycosylation occur in
starts in ER and continues in golgi
135
what is protein glycosylation
attaching oligosaccharides to complete processing of proteins
136
endosomes are
membrane bound organelles containing material ingested by endocytosis
137
early endosomes
endocytic vesicles fused to early endosomes and ingested material is sorted, also lysosomal proteins are delivered to it
138
late endosomes
lysosomal proteins delivered from trans golgi network
139
example of lysosomal proteins
acid hydrolases, h+ pump
140
lysosomes occur when
most of the stuff has been digested, contains sufficient hydrolytic lysosomal enzymes to digest everything in it
141
what hapepns after lysosome maturation
lysosome fuses with endosome to reuse enzymes
142
how are lysosomes acidified
h+ pumps
143
why are lysosomes acidic
low ph for hydrolytic enzymes
144
what's special about lysosomal membrane proteins on the non cytosolic face
glycosylated to protect from proteases
145
