Chapter 12 - Transport Across Cell Membranes Flashcards
1
Q
Transport proteins
A
Allow many water soluble molecules to move across hydrophobic region of cells membranes
2
Q
Protein free artificial lipid bilayer
A
Impermeable to most water soluble molecules except for water
3
Q
Why are proteins negatively charged
A
Due to carboxyl group
4
Q
Sodium concentration is higher where
A
Outside the cell than inside
5
Q
Potassium concentration is higher where
A
Inside than outside
6
Q
Sodium is balanced by what
A
Chlorine
7
Q
Potassium is balanced how
A
Variety of negatively charged ions and molecules
8
Q
Transporter aka
A
Carrier
9
Q
Transporter
A
Membrane protein that undergoes series of conformational changes to transfer small hydrophilic solutes across the liquid bilayer
10
Q
Channel
A
Hydrophilic pore across the lipid bilayer through which specific inorganic ions or polar organic molecules can diffuse
11
Q
Channels discriminates by
A
Size and electrical charge
12
Q
Transfers molecules at much greater rate than transporter
A
Channels
13
Q
Ion channel can exist either in _____ or ________ conformation, but it transports only in the _______ conformation
A
Open , closed
Open
14
Q
Transporters carry out _______________ while channels carry out ___________
A
Passive and active transporters
Passive transport
15
Q
Passive transport allows solutes moves
A
Down their concentration gradient
16
Q
Simple diffusion
A
Gases and hormones
17
Q
Facilitated diffusion
A
Sugars and inorganic ions
18
Q
Facilitated diffusion consist of
A
Transporters and channels
19
Q
Active transport
A
Allows solutes to move up or against concentration gradients from regions of their lower to higher concentration gradient…requires energy
20
Q
Osmosis
A
Movement of water
21
Q
Osmosis moves
A
Down their concentration gradient
22
Q
Isotonic solution
A
Has the same concentration of solutes as the cell
23
Q
Hypotonic solution
A
Has much lower concentration of solutes than the cell
24
Q
Hypertonic solution
A
Has much higher concentration of solutes than the cell
25
Plastmolhysis
Plasma membrane pulls ways from cell wall
26
Turgid
Swollen
27
Plants love what type of solution
Hypotonic solution
28
Contractile vacuole does what
Removes excess water
29
Where is contractile vacuole only found where
In protist
30
Central vacuole found where
Plants
31
Aquaporins
Accelerate the movement of water molecules they are water molecules, they are water channels
32
Lysosome membrane contains what and does what
H+ transporter; acidified the lysosome interior
33
Innner mitochondrial membrane contains what
Transporters for important pyruvate and exporting ATP
34
Glucose transporter
Mediates passive transport of glucose into liver cells
35
What happens after a carb rich meal
Beta cells of pancreas, secret insulin that cause liver cells to convert excess glucose to glycogen
36
What happens when we are fasting of exercising
Our cells of pancreas secreate glucagon that causes liver cells to break down glycogen to glucose
37
Cells drive active transport in 3 mains ways
Gradient driven pump
ATP driven pump
Light driven pump
38
ATP driven pump: Na/K pump plays key role in what type of cells
Animal
39
Na/K uses energy of what to pump Na+ out of the cell and K+ in, both agains their electrochemical gradients
ATP hydrolysis
40
Na/K pump transports what
3 Na out
| 2 K in
41
Na/K+ is not only the transporter but what else
Enzyzme
42
SR stands for
Sarcoplasmic reticulum
43
Where can you find SR
In skeletal muscles cells
44
When skeletal muscles are stimulated Ca+ ions move where and how is it able to move?
From lumen of SR to cytosol
Because of Ca2+ release channel down their electron gradient
45
When muscles contract which way does their electron gradient move and by which transport
Down their electron gradient by passive transport (facilitated diffusion)
46
What happens when muscles relax
Calcium move from the cytosol to the lumen of SR through calcium ion pump
47
When the muscles relaxes the calcium move how ...their gradient
And using what transport
Up their electrochemical gradient using active transport
48
What is the purpose of the calcium pump
Returns the calcium to the SR in the skeletal muscle cells
49
What does the calcium pump need in order to work
ATP
50
What type of pump is Calcium pump
ATPase
51
How is the calcium pump similar to Na/K pump
Calcium and sodium/k pump requires atp and is an ATPase
52
How are calcium pump different from Na/K pump
No binding or transporting of second ion
53
Gradient driven pumps can act as
Symports or antiports that carries 2 solutes
54
Symports
When transporters move both solutes in the same direction across the membrane
55
Antiport
When transporter moves both solutes in the opposite directions across the membrane
56
Uniport
Only one type of solute is transferred across the membrane
57
Uniport are not what? And why
They are not pumps because pumps require energy. Uniports don’t requires energy and moves down their concentration gradient
58
Glucose transporters
Enable gut epithelial cells to transfer glucose across the gut lining
59
At the apical surface how is glucose is actively transported how into the cell
Glucose-Na+ symport
60
At the basal and lateral surface, how is glucose moved
By passive glucose uniports, they release down its concentration gradient
61
Glucose concentration is higher where
Gut epithelial cells
62
How does glucose enter the gut epithelial cells
How does glucose leave
Actively through sodium symport
Leaves passively via glucose uniport
63
How does sodium enter the gut epithelial
How does sodium leave the cell
Sodium enters by passively via glucose/na symport
Leaves by actively via Na/K pump to actively via Na/K pump
64
The H pump aka
H+ ATPase
65
The electrochemical gradient of H+ in the plants, fungi, and bacteria serves similar function as to what in animals
Electrochemical gradient of Na+ in animals
66
What is the correlation with lysosomes and hydrogen
Lysosomes has a higher concentration inside then inside the cytosol
67
The H pump in plant cells are what
ATP driven pumps
68
Why is H pumps important for animal and plant cells
They keep internal ph of lysosomes (in animals and plants) and vacuoles (in plants) acidic
69
What surrounds the central vacuole
Tonoplast
70
What are the gradient driven pumps
Na+/glucose pump
71
What are ATP driven pumps
Sodium
Calcium
Hydrogen
72
What is the type of light driven pumps
Bacteriorhodopsin
73
Where is Na/glucose pump (symport) located
Apical plasma membrane of kidney and intestinal cells
74
What is the function of na/glucose pump (symport)
Active import of glucose
75
What is the energy source of na/glucose pump
Sodium gradient
76
Sodium and hydrogen exchanger is located where
Plasma membrane of animal cells
77
Sodium hydrogen exchanger energy source is what
Sodium gradient
78
Sodium hydrogen exchanger function
Active export of hydrogen ions, pH regulation
79
Sodium pump location
Plasma membrane of mostly animal cells
80
Energy source of sodium pump
ATP hydrolysis
81
What is the function of sodium pump
Active export of Na and import of K
82
Calcium pump is located where
Plasma membrane of eukaryotic cells
And sarcoplasmic reticulum membrane of muscle cells and Er membrane of most animal cells
83
Calcium pump gets its energy source from
ATP hydrolysis
84
What is the function of calcium pump
Active export of calcium
Active import of calcium into SR OR ER
85
H pumps are located where
Plasma membrane of plant cells, fungi, and some bacteria
Membranes of lysosomes in animal cells and vacuoles in plant and fungal cells
86
Energy source of H pumps
ATP hydrolysis
87
Function of H pumps
Active export of Hydrogen
Active export of hydrogen from cytosol into lysosome or vacuole
88
Bacteriorhodopsin location
Plasma membrane of bacteria
89
Energy source of bacteriorhodopsin
Light
90
Bacteriorhodopsin function
Active export of hydrogen
91
Bacterial K Channel is unique because
It shows ion selectivity
92
Bacterial k channel depends on
Diameter and shape of the ion channel, and on the distribution of the charged amino acids that line it
93
Concentration of K is higher where in bacteria cells
Higher inside the cell
94
What ions are able to pass through bacterial k channel
Only ions of appropriate size and charge
95
How are the ions pass through the bacterial k channel
Each ion is surrounded by a shell of water molecules, most of which must be shed for the ions to pass through
96
Most ion channels are what
Gated
97
What is gated mean, relative to channels
Switch between open and closed conformations
98
How does membrane potential occur
Due to uneven distribution of positive and negative charges across the membrane
99
The K leak channels play a major role in
Generating the rest membrane potential across the plasma membrane
100
Resting membrane potential
Voltage or charge difference across plasma membrane addressed
101
Leak
Means open all the time
102
Plasma membrane is more permeable to what
K ions than Na ions
103
The purpose of patch clamp recording
Used to observe the behavior of single ion channel
104
Sarcolemma
The membrane of the muscle cell
105
Sarcolemma contains what and why is that important
Single ion channel protein that is to the neurotransmitter acetylcholine
106
Neurotransmitters
Chemical transmitters released mainly by nerve cells
107
What causes Ion channel to open
To allow passage of positive ions when acetylcholine binds to it
108
What happens to ion channels without acetylcholine
Ion channels spends most of its time in closed conformation
109
Even though acetylcholine is bound to the channel what is a possibility
The channel doesn’t remain open all the time
110
What are the four gated ion channels
Voltage gated
Ligand-gated (extracellular ligand)
Lingand-gated (intracellular ligand)
Mechanically gated
111
Voltage gated channel
Opens in response to a change in the membrane potential across the membrane
112
Ligand gated channel (extracellular ligand)
Open in response to a binding of a chemical ligand (neurotransmitter) to the channel protein
113
Mechanically gated channel
Opens in response to mechanical stress
114
Cochlea
The auditory portion of the mammalian inner ear
115
Corti hair cells are embedded where
Which is between where
Sheet of supporting cells, between the basilar and tectorial membranes (sheets of ECM)
116
Sterereocilia
Hair cell that spiky extensions
117
What channels allows us to hear
Stress gated ion channels
118
Why are sound vibrations important for us to hear
They cause the basilar membrane to vibrate up and down, causing stereocilia to tilt
119
How are stereocilia connected to one another
Linking filaments
120
When stereocilia tilt, what happens to the filaments and by that action what happens to the mechanically gated ion
Filaments stretch, pulling open the channel
121
Positively charged ions enter what and does what to the auditory nerves
Enter the stereocilia and activate the hair cells, which stimulate auditory nerves to convey signal
122
Neurons
Nerve cells
123
What is the basic structure of a neuron
Cell body
Dentrites
Axon
Terminal branches of axon
124
Cell body in a neuron contains
The nucleus
125
Dendrites
Short cytoplasmic extension that receives signals from the axon of other neurons
126
Axon
A single, long extension that conducts signals away from the cell body
127
Terminal branches
Pass the neurons message simultaneously to many target cells; other neurons, muscle, or gland cells and endothelial cells
128
Action potential aka
Nerve impulse
129
Action potential can carry what
A message without the signal weakening
130
Action potential results from
Rapid change in the membrane potential that is caused by local stimulus
131
What happens when there is an action potential with the channels
Chemically gated Na channels (ligand gated) open temporally and causes depolarization of the plasma membrane at that particular spot
132
Depolarization
Shift in the membrane potential to less negative value
133
When there is an action potential why is depolarization a less negative value
Due to the rush of Na into the cell
134
Depolarization stimulates what and leads further to what
Voltage gated Na channels leading to depolarization
135
What is the resting membrane potential of a neuron
-60mV
136
What is the threshold value for action potential
-40mV
137
The voltage gated Na+ channels can adapt at least to how many conformations and what are they
3; open, closed and inactivated
138
A rest the membrane is what
Is polarized
139
How is it that after action potential, the plasma membrane returns to resting potential
Voltage gated Na channels automatically switch to inactivate state
Voltage gated K channels open allowing k to move out of the cell
140
Synapse
The site of contact between neuron (presynaptic cell)and its target (postsynaptic cell)
141
synaptic cleft
Small space between neurons at a nerve synapse
142
What is unique about chemical signals vs electrical signals when it comes to the synaptic cleft
Electrical signals can not jump across the synaptic cleft but chemical signals (neurotransmitters can))
143
Neurotransmitters are what
Chemical signals
144
Neurotransmitters/ chemical signals are stored where
Synaptic vesicles
145
What are the most common neurotransmitters
Acetylcholine, epinephrine (adrenaline), and glycine
146
Epinephrine is also known as
Adrenaline
147
The acetylcholine receptor is what type
Transmitter gated ion channel
148
Where can acetylcholine receptor be found
In the plasma membrane of muscle cells
149
The acetylcholine receptor is made up of what
5 protein subunits
150
The acetylcholine receptors protein subunits for what? To ensure what?
Aqueous pore whose negatively charged amino acids ensure that only positively charged ions can pass
151
What happens when the acetylcholine binds to the channel
Causes conformational change in which these side chains move apart and the gate open, allowing Na to flow through he membrane, causing it to become depolarize
152
Example of excitatory neurotransmitter
Acetylcholine
153
Example of Inhibitory neurotransmitter
Glycine
