TEST 2 Flashcards
(133 cards)
1
Q
Why cant hydrophilic/polar molecules cross the bilayer?
A
Due to hydrophobic/nonpolar interior of membrane
2
Q
Simple diffusion
A
High to low concentration by itself
3
Q
facilitative transport
A
accelerated transport across membrane using transport proteins
4
Q
What governs rates of protein diffusion across protein free bilayer?
A
size and solubility (hydrophobic/philic)
5
Q
membrane transporter proteins
A
moves molecules across bilayer- transporters and channels
6
Q
Transporters
A
moves 1 type of molecule across membrane- mostly organic molecules-
can use ATP which is active transport
7
Q
Channels
A
moves molecules into cell of certain size and charge- mostly ions
usually passive transport
8
Q
smalll nonpolar molecules diffusibility to bilayers
A
diffuse through membrane easily -02 C02
9
Q
large uncharged molecules diffusibility to bilayers
A
VERY SMALL amount through- amino acids & glucose
10
Q
small charge polar molecules diffusibility to bilayers
A
small amount makes it through - H20 glycerol
11
Q
ion molecules diffusibility to bilayers
A
none go through w/o membrane transporter protein- H+ K+ Na+
12
Q
liposome/bilayer w/o proteins solubility
A
impermeable to hydrophilic/polar moelcules
diffusion is only way to cross
13
Q
resting membrane potential
A
charge of cell compared to outside
made by high concentration of certain charged ions in cell compared to surroundings
cell is usually negative and surroundings is positive
14
Q
Na+ concentrations
A
high outside cell
balanced by CI-
15
Q
K+ concentrations
A
high in cell
balanced by charge of proteins
16
Q
Concentration of solute in solvent
A
governs whether water will enter or exit cell
17
Q
How protezoen cells deal with excess solute/solvent
A
expell excess water from cell by contracting vaculoles
18
Q
How plant cells deal with excess solute/solvent
A
the cell wall prevents swelling can tolerate large pressures and vacuole to regulate waterflow
19
Q
How animal cells deal with excess solute/solvent
A
increase/decrease ion concentrations in cell
20
Q
Glucose transporters after meal
A
glucose in plenty outside of cell, sugar binds to binding site then protein will switch orientation to bring it into cell
21
Q
glucose transporters before meal
A
glucose is plenty inside cell
glucagon stimulates cells to produce glucose from breakdown of glycogen
glucose binds to protein in cytosol then the protein will switch orientation bringing it out of cell
22
Q
Gradient driven pumps
A
links uphill transport of solute across bilayer to downhill transport of another
23
Q
ATP driven pump
A
uses energy from ATP to drive transport
24
Q
light driven pump
A
uses energy from light to drive transport
25
Sodium pump
```
uses ATP
antiport
30% of total ATP use in organisms
3 Na+ out 2 K+ in
creates negative cell potential
```
26
Ouabain function to what
Affects Sodium/potassium pump
| completely stops all function of pump by stopping uptake of potassium
27
Ca+ affects on cell and pump type
uniport
the lower the concentration the more sensitive
low dose is kept in cell
kept low by Ca+ pump in ER and membrane,
28
symport
moves 2 molecules in same direction
29
antiport
moves 2 molecules in opposite direction
30
uniport
moves 1 molecule in 1 direction
31
Glucose uniport transporter
if it was the only thing used in gut, glucose would be immediately dispersed entirely to body
transports glucose from gut cells to extracellular fluid
passively diffuses glucose to body
32
glucose/na+ symport transporter
alllows pumping of glucose into cell against concentration gradient -low to high
this is due to electrical gradient of Na+, Na+ wants to go into cell so it drags glucose in with it using the transporter
actively takes up glucose
33
Sodium/proton pump
antiport
lets Na+ in to expell H+
helps control pH of animal cell
34
Proton/sodium pump
used in only plant and bacterial cells
controls pH
pumps H+ out of cell- this gradient helps pull in solutes in the same way as the Na+/glucose symport by having the H+ pull in the solute
35
Channels do what to not let molecules freely float between cytosol and extracellular fluid
only a narrow selective passage is available that only allows a specific type of molecule
opens and closes
36
Benefits of Channels
they don't undergo conformational changes- makes it very fast compared to transporters
37
K+ leak channels
allows K+ to move across membrane freely
equilibrium is maintained as K+ ions don't often leave cell unless a large surplus of them is present
the electrochemical gradient for K+ is 0 even though there is a higher concentration of K+ inside cell than out
38
patch clamp recording
syringe is inserted into membrane to extract patch of membrane
the ion flow and electric charge is measured from the extra syringe and intra syringe areas that are separated due to the patch
chart shows differences between charges when channels open and close
39
Voltage gated ion channel & examples
being open is controlled by membrane potential
| muscle cells egg cells proteozoans plant cells
40
Voltage sensors & voltage gated ion channels
Voltage sensors are sensitive to changes in membrane potential
eventually the sensor encourages the voltage gated ion channel to close
the potential only affects the chance itll close
41
ligand gated channel
opened by molecule binding to channel
| can be intra/extracellular
42
mechanically gated channel
opening is controlled by force applied to channel
43
what is the long part of the neuron/transmits signals
axon
44
what is the point where the axon joins the cell body of the neuron
axon hillock
45
what splays out from the cell body of a neuron
dentrites
46
what covers the axon
mylin sheaths
47
which direction does an action potential go along the neuron
from the dentrites to cell body to the axon
48
branches of the axon are called what
nerve terminal
49
dentrites cover a wide surface area for what
to recieve signals from other axon ends
50
40mV
peak of ap
51
-70mV
normal cell resting potential
52
-70mV
normal cell resting potential
53
sodium channels before during after AP
Na channels open during AP, inactivate after AP to stop AP from traveling in more than 1 direction, then close once AP is far enough away
54
sodium channels before during after AP
Na channels open during AP, inactivate after AP to stop AP from traveling in more than 1 direction, then close once AP is far enough away
55
K+ during AP
K+ leaves the cell during an AP through its channel to equalize charge in the cell, after the AP the sodium leaves the cell and the K+ diffuses back into the cell
56
How were Na+ and K+ found to be used in AP's
scientists removed a section of neuron, removed the insides and refileed it with Na+, K+, and Cl-
they found an AP could only be generated when Na and K were equal inside cell at 40mV
57
how was the dynamics of K and Na found out during an AP
at resting membrane potential it was found the K+ was at equilibrium inside and out of cell, most permeable to membrane
at AP Na was found to be at equilibrium in and out of cell, most permeable to membrane
58
How are APs transmitted from cell to cell
AP transmits to nerve terminals
AP opens Ca2+ channels
Ca2+ channels cause synaptic vesicles containing neurotransmitters to fuse with the cell membrane releasing the neurotransmitters into the synapse
59
synaptic vesicle
contains neurotransmitters in presynaptic cell
60
how are chemical signals from synapse turned into APs in the receiving cell
a transmitter gated ion channel receives the neurotransmitter which opens an ion channel allowing usually Na+ into the cell which creates another AP in the receiving cell
61
excitatory neurotransmitters
acetylcholine & glutamate
| these transmitters depolarize the cell to allow for easier creations of AP's
62
inhibitory neurotransmitters
GABA & glycine
further polarize cell makes it harder to create AP
done using Cl-
63
what is used at the neuromuscular junction
an acetylcholine receptor
64
Acetylecholine receptor function
receptor is closed to ions when not bound to acetylcholine
receptor opens up to ions when bound
made up of 5 units
stimulates muscle contraction
65
Curare
causes muscle paralysis
| blocks acetylcholine receptors not allowing for contraction of muscles
66
strychnine
causes all muscles to activate/flex by blocking inhibitory glycine receptors on all neurons
67
Ambien
binds to GABA gated Cl- channelks makes cell more sensitive to inhibitions due to GABA
68
Prozac
blocks Na+/seratonin symport that uptakes seratonin back into presynaptic vesicles which leaves seratonin in synapse causing effects of seratonin on reciveing cell much stronger
69
double membrane organelles
mitochondria, chloroplasts, nucleas
70
How much do organelles take up in the cell
50%
71
how did the nuclear double membrane form
invagination of cell membrane around nucleas
72
how did the mitochondria double membrane evolve
a cell enveloped another cell, kept it alive for ATP synthase which turned into the mitochondrion
73
Organelles in the endomembrane system
ER, golgi, peroxisomes, endosomes and lysosomes
74
endomembrane system communicate w other cells how
by making and secreting vesicles full of proteins to outside of cell to signal to other cells
75
Relationship between ER and nuclear membrane
ER is continuous with nuclear membrane
76
rough ER
synthesizes proteins into lumen (inside) of ER
makes new membranes
B cell have a ton of this
77
smooth ER
very few in cell
lacks ribosomes
synthesizes sterioids in adrenal gland
creates molecules to detox alcohol in liver
78
proteins lacking sorting signal
floats in cytosol
79
organelles that can recieve proteins directly from cytosol, skipping the ER
nucleus, mitocondria, chloroplast
80
process of proteins after synthesis
proteins travel to ER
then to golgi to be packaged for a new organelle
then to golgi lysosomes endosomes and inner nuclear membrane
81
what would happen if an ER signal sequence were removed from an ER protein and spliced onto a cytosolic protein
the cytosolic protein would be rerouted to the ER
82
what would happen if a protein contained a nuclear export signal and a nuclear localization signal
the cell would move back and forth between the two
83
where are mitochondrial and chloroplast proteins made
ribosomes inside the mitochondira/chloroplast
84
process by which protein is imported into nucleus
proteins go through nuclear pores, penetrating both double layers
85
process by which protein is imported into ER mitochondria and chloroplast
protein unfolds
86
what would happen if a protein contained an ER localization signal and a nuclear localization signal
it would go to the ER?
87
nuclear envalope
2 membranes
inner membrane has proteins to bind for nuclear lamina which is a meshwork. of proteins to provide structural support to envelop
Outer membrane is similar to ER membrane as its continuous
88
To get into the nucleus proteins have to do what
it has to pass through a kelp forest of proteins in the pore
this kelp forest discriminates what gets in and out
the protein then has to bind to a nuclear import receptor, these receptors
guide the protein through the kelp forest to get into the nucleus
the receptor goes back to the cytosol through the pore
this process uses GTP
89
how/what does a nuclear pore stop from coming into the nucleus
the pore allows in smalll water soluable molecules in
stops large molecules in
does this by having a large number of proteins covering the pore creating a sort of kelp forest that only specific proteins and get through
90
to get into the mitochondria proteins have to do what
proteins will bind to a protein translocator in outer-membrane
the translocator will move around to find the same protein on the inner
membrane
the protein will then unfold to fit through both membrane transporters
once inside the mitochondria chaperone proteins bind to the incoming
protein to assist it coming into the cell
once fully in the chaperone proteins sluff off and a cleaver protein cleaves
off the signal sequence
91
how do proteins get into the peroxisomes
most come directly from selective transport from the cytosol
| some come inside vesicles from ER
92
what organelle serves as an entry point for proteins destined for all organelles or cell surface
the ER
93
Water soluble proteins transferred from cytosol to ER do what
translocated into the ER membrane then into ER lumen
| can be secreted or transferred to other organelle in endomembrane system
94
Transmembrane proteins transferred from cytosol to ER do what
partly translocated across ER membrane and become embedded into it
95
Free ribosomes
floating ribosomes in cytosol
| making proteins from DNA
96
Membrane bound ribosome
attached to cytosolic side of ER membrane
97
energy for transport of proteins into ER
no source of energy is needed as the signal sequence is all it needs
98
Define polyribosome
many ribosomes bound to the same mRNA sequence translating it
if the protein has an ER signal sequence the ribosomes will move towards the ER while translating it
99
SRP-signal recognition particle
present in cytosol
| binds to ribosome and ER signal sequence as it emerges from the protein being created by the ribosome
100
SRP receptor
embedded in ER
binds to SRP
once bound protein synthesis is slow
once bound the SRP is released and the receptor binds the ribosome to a
protein translocator
once the ribosome is bound to the translocator protein synthesis restarts, but this time the protein will be created into the lumen of the ER
101
function/fate of ER signal sequence
this opens the translocator, this sequence stays bound to translocator while protein synthesis continues threading through forming a loop
once finished the sequence is removed from the protein and translocator by an enzyme where it is then degraded
102
process creating of single pass transmembrane protein
ribosome is bound to ER from SRS & SRS receptors and was put into a translocator to continue protein synthesis
one part of the protein codes for the protein translocator to let go of the
protein which then continues protein synthesis
this leaves one half of the protein in the ER lumen and one half in the cytosol
the signal sequence is cleaved off and destroyed
103
process of creating multipass transmembrane proteins
a signal sequence in the middle of a protein gets put into a translocator
the other side of the protein gets theaded through the translocator
a stop-transfer sequence gets fed through and the translocator leave the
protein creating a multipass protein
the signal sequence stays in the membrane
104
exocytosis
excretion of proteins from the cell in vesicular transport
| golgi packages these before sending them out
105
endocytosis
receiving proteins from extracellular area by having them aggregate into a vesicle, then into the cell
106
function/fate/creation of protein coats on vesicles
created from parent organelle's membrane- lysosome has proteins on its
membrane, shedding them off after leaving organelle to interact directly
with another
membrane
helps shape membrane into a bud and captures molecules for onward
transport
107
how do clathrin molecules form a vesicle
clathrin molecules assembly together on the plasma/golgi membrane
they then start to pull the membrane inward into a pit, then using GTP dynamin forms around the neck of the pit and pinches the vesicle off from the membrane
inward from the plasma outward from the golgi
clathrin is removed after the lysosome has been formed
108
how do clathrin molecules choose the molecules they transport
adaptins secure clathrin coat to membrane and choose cargo through their receptors which recognize and bind to proteins transport signals
different adaptins are used for the golgi and the plasma membrane
109
How do receiving membranes dock/tether with incoming vesicles
1st step- a specific RAB protein is expressed on the surface of each vesicle, these are recognized by tethering proteins that catch the cell by the RAB protein, each RAB protein/ tethering protein is unique to its receiving organelle
2nd step- once the RAB protein has had the vesicle be "caught" by the receiving organelle this step starts.
A vSNARE is expressed in the vesicle interacts with a tSNARE on the reciveving organelle docking the vesicle into place
3rd step- the SNARES help fuse the vesicle membrane into the organelle membrane, the intertwining v/tSNAREs pull apart the vesicle stretching it into the larger membrane,
this process is energetically unfavorable because water has to move for it to occur therefore this fusing is NOT random
110
Disulfide bonds
this is done to proteins in the ER
covalent
formed by oxidation of pairs of cysteine side chains
this helps stabilize protein against degrative enzymes and changes in pH
111
Glycosylation
done to proteins in ER
creates glycoproteins by binding oligosaccharide side chains of many surgars to protein
this protects protein from degredation, hold it in ER until properly folded, act as a transport signal for packaging into correct vesicle
can act as apart of glycocalyx
112
In glycosylation how are proteins chosen and how are sugars added to the protein
the sugars are added to the protein ALL AT ONCE by a ER membrane bound protein
the sugars are initally bound to a lipid in the membrane, then as the growing protein is being fed through the membrane the sugar is added all at once when the asparagine is fed through the transport protein
113
how are incorrectly folded proteins kept in the ER until corrected
proteins that are incorrect are held back by chaperone proteins before escaping, these proteins prevent aggregation of misfolded proteins
if proper folding doesnt occur they are exported to cytosol for degredation
114
How are proteins that work in the ER kept in the ER
ER proteins are held in the ER by a ER retention signal, this is recognized in the ER and golgi
115
Define Unfolded protein Responce
when improperly folded proteins aggregate in the ER this responce is triggered
this creates more ER and chaperone proteins
if the larger amount of ER still cant handle a large amount of proteins the cell undergoes apoptosis
this occurs in diabetes, when the body becomes immune to insulin, the insulin creating cells try to make more insulin but become overloaded and die, making the diabetes worse
116
Structure/location of golgi
near nucleus/centrosome
flattened membrane enclosed sacs stacked on top of each other
these sacs are called cisterna
each stack has 3-20 cisterna
cis- entry point next to ER
trans- exit point towards plasma membrane
117
How do proteins travel through cisterna in the Golgi
1-by transport vesicles that bud onto one cisterna and fuse with the next one
2-by a maturation process where the golgi cisternae themselves migrate through the golgi, where the proteins then exit the golgi from the trans side
118
how are proteins sorted in cis golgi
proteins go onward through the golgi
or
return to ER if they have an ER retention signal
119
how are proteins in the trans golgi sorted
sorted by destination
lysosome
or
cell surface
120
how/where oligosaccarides are added to glycoproteins in golgi
can be added in cis (early on) and trans (late stages in golgi)
added with enzymes that act in determined sequence to adding proteins to glycoproteins
121
constitutive exocytosis pathway
a constant stream of vesicles budding from the trans golgi, which fuses with plasma membrane
supplies membrane with new lipids and proteins
can also secrete proteins; some to join extracellular matrix
no signal sequence needed
122
regulated exocytosis pathway
operates only in cells specialized for secretion
these cells secrete their product (horomones digestive enzymes etc.) in large quantities
the vesicles aggregate at plasma membrane and wait for signal to release
123
how does the plasma membrane gain/lose lipids
gains by fusing membranes with vesicle
| loses by creating vesicles
124
Green Flourescent Protein function
can be attached to other proteins with little to no impairment of function of said protien
can be viewed with fluroesecence microscope
125
how mutant proteins showed the secretory pathway
mutant proteins were created at high temperatures
the temp is raised again and the proteins multiply spilling out of all organelles in the secretory pathway showing what organelles are involved
126
protease shows what proteins go in an organelle how
2 protiens will be in the cell
free proteins and ones introduced into an organelle with a protease
only those that make it into the organelle will show up in the sediment of the organelle and not anywhere else
the free floating protiens will show up separate of the protease protiens even tho they are almost the same
127
cells that engage in phagocytosis
macrophages neutrophils-WBC
| protozoa
128
process of phagocytosis
receptors on WBC that bind to the pathogen which triggers pseudopods to extend around pathogen to engulf it and then fuse the endosome with a lysosome for digestion
129
pinocytosis doesn't decrease cell surface how
because the same amount of vesicles are leaving as they are entering the membrane due to endo and exo cytosis
130
receptor mediated endocytosis
a particle activates a receptor on the membrane
that receptor activates formation of a vesicle to intake the particle
for example the intake of cholesterol in LDL, LDL binds with a receptor, then is intook by clathrin coated vesicle, binds with an endosome to release LDL, then the receptor and vesicle return to the membrane
viruses can use this pathway to their advantage, being taken up by immune cells via receptor mediated endocytosis, where the environment inside is better for them to replicate
131
how do lysosomes keep a low pH
proton pumps keep the lysosome acidic which is the best environment for the enzymes inside
132
how are endosomes kept acidic inside
proton pumps
| the acidic environment helps sort cargo into the endosome so that only correct ones will go inside
133
what enzymes are in lysosomes
```
pretty much any enzyme that can break down everything in the cell
nucleases
proteases
glycosidases
lipases
phosphatases
sulfatases
phospholipases
```
