Cell Membrane, Membrane Transport, and Membrane Potential Flashcards
(120 cards)
1
Q
______ functions to Separate cytoplasm from ECF, Regulate exchange between ECF and Cytoplasm, Communicate with other cells, and Provide structural attachments between cells or between cell and extracellular matrix.
A
Plasma Membrane
2
Q
Plasma membrane structure is described by ____ model
A
Fluid Mosaic Model
3
Q
What are the 4 different types of organic molecules that make up the plasma membrane?
A
phospholipids, steroids, proteins, and carbs
4
Q
______ are Amphipathic, Organized into a bilayer, and Functions: Creates Barrier
A
Phospholipids
5
Q
What are the heads of phospholipid polar or non-polar?
A
Polar
6
Q
What are the tails of phospholipid polar or non-polar?
A
Non-polar
7
Q
Hydrophobic substances: Small, nonpolar molecules, Ex. (Gases (O2, CO2), Fatty acids, steroids, Lipophilic substances•Ex. Ethanol, and Water are _______ for phospholipids (Permeable or non-permeable)
A
Permeable
8
Q
Larger molecules, Polar molecules, and Charged substances (Glucose, Ions, Amino acids, and Proteins) are _____ for phospholipids (Permeable or non-permeable)
A
Non-permeable
9
Q
_____ are incorporated into plasma membranes Help keep membrane fluid over a wide range of temperatures and Help to make membrane water tight
A
Cholesterol
10
Q
For proteins ____ determines function
A
Shape
11
Q
What are the factors that alter protein shape?
A
Mutations, pH, Temp, Osmolality, and Covalent/Allosteric Modulation
12
Q
A mutation alters the ____ structure of the protein
A
Primary
13
Q
Changes in ph, Temp, or Osmolaltiy alters the ______ structures of the proteins and causes _____
A
Secondary, Tertiary, and Quaternary; denaturation
14
Q
Covalent/Allosteric Modulation changes the ____ structures of a protein
A
Secondary, Tertiary, and Quaternary
15
Q
What are the 3 structural classifications of a protein?
A
Transmembrane, Integral, and Peripheral
16
Q
______ Bind to specific chemical signals (ligands) and transmit that information to the cytoplasm
A
Receptors
17
Q
Shape of the binding site determines what will bind; Each type of protein, in general, will interact with only one type of substance or class of substances
A
Specificity
18
Q
______ refers to the fraction of total binding sites that are occupied at any given time; Dependent on [protein] and the [substance]
A
Saturation
19
Q
A _______ is a chemical substance (exogenous ligand) that binds to the active site of the protein and blocks the endogenous ligand from binding
A
competitive inhibitor
20
Q
A chemical substance that comes from outside the body
A
exogenous ligand
21
Q
A _____ will also activate a receptor
A
agonist
22
Q
A ____ will block receptor activity
A
antagonist
23
Q
Response of a cell to a chemical signal is _____ mediated
A
receptor mediated
24
Q
If there is no receptor, there is ____ response
A
no response
25
If 2 different ligands bind to the same response, they will elicit _____ response
same response
26
If one ligand binds to 2 different receptors, it will elicit ____ response
2 different responses
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Strength/Ease of ligand-receptor binding; proportionate to # ligands bound to receptors at any given
Receptor Affinity
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____ is the ligand concentration where half of the receptors are occupied
Kd
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Affinity is ____ to Kd
inversely related
30
Transmembrane proteins with a 3D shape that forms a tiny fluid filled pore connecting ECF and Cytoplasm
Channels
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_______ function in Facilitated diffusion of ions into and out of cell (passive; does not require energy); Can be somewhat specific (Ca++ channel, Na+ channel, Cl-channel, cation channel, etc.)
Channels
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Always open and ions freely flow through via facilitated diffusion; Creates “Leak Currents”
Open Channels
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Spend most of their time in the closed state, and will open only when stimulated; Three types: a. Chemically gated b. Mechanically gated c. Voltage gated
Gated Channels
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____ modulation is seen in ligand-gated channels; displays non-covalent bonding and don't need a catalyst
Allosteric modulation
35
____ modulation uses kinases and phosphatases; displays covalent bonding and needs a catalyst
Covalent modulation
36
Transmembrane protein that moves hydrophilic building blocks across the plasma membrane via facilitated diffusion (passive; does not require energy); changes shape
Carriers
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Transmembrane protein that moves ions and hydrophilic building blocks across the plasma membrane via active transport (Active; requires energy).
Active Transporters
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____ proteins Forms cell to cell attachments that hold adjacent epithelial cells together
Structural Proteins
39
_____ junctions Prevents intercellular movement of fluid and dissolved substances
Tight Junctions
40
_____ are junctions for Structural Support
Desmosomes
41
_____ junctions function in Cell to Cell communication via ions
Gap Junctions
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Integral membrane, transmembrane, or peripheral membrane proteins that catalyze specific chemical reactions either on the extracellular surface of cell or inside cell.
Enzymes
43
______ are Attached to extracellular surface of membrane lipids and proteins
Carbohydrates
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made up of Glycolipid and carbs; Plays important role in enabling cells to identify and interact with each other.
Glycocalyx
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In ____ transport, No energy required; Down gradients (high to low; ΔC, ΔP or ΔE); Types-Diffusion-Osmosis-Bulk Flow
Passive Transport
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In ____ transport, Energy required; *Up gradients (low to high); Types-*Active Transporters-Bulk (Vesicular) Transport
Active Transport
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Molecules in a fluid are continuously and randomly bouncing aroundRate of movement proportional (T) and inversely related to (Mass)
Random thermal motion –
48
Movement of substances other than water down a gradient (ΔC; ΔE or ΔP; high to low). Net movement stops at equilibrium, Random movement is continuous, and is Substance specific
Diffusion
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____ transport moves the system towards equilibrium
Passive transport
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Type of diffusion: Hydrophobic/Lipophilic SubstancesMove directly through phospholipid bilayerSlowerUnregulatedDoes not require a plasma membraneDiffusion rate α (ΔG)(T)(A)/(R)(D)
Simple Diffusion
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Type of diffusion: Hydrophilic/Lipophobic SubstancesRequire membrane channels or carriersFasterRegulated (specificity, saturation, competition)Requires plasma membrane Diffusion Rateions α (ΔG)(T)(#Channels)(Popen)Or molecules α (ΔG)(T)(#Carriers)
Facilitated Diffusion
52
Is Na higher on the inside or outside of cell?
Outside
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Is K higher on the inside or outside of cell?
Inside
54
Is Ca higher on the inside or outside of cell?
Outside
55
Is Mg higher on the inside or outside of cell?
Inside
56
Is Cl higher on the inside or outside of cell?
Outside
57
Is HCO3 higher on the inside or outside of cell?
Outside
58
Is Phosphates higher on the inside or outside of cell?
Inside
59
Is glucose higher on the inside or outside of cell?
Outside
60
Is amino acids higher on the inside or outside of cell?
Inside
61
Is pH higher on the inside or outside of cell?
Outside
62
Are proteins higher on the inside or outside of cell?
Inside
63
T/F: It takes about 2 hours to synthesize proteins; many are synthesized in advance and stored in an inactive form, activated when needed; provides a means for immediate protein regulation
True
64
The interaction between substance and protein binding site follows the ____ model
Mass Action Model
65
Movement of H2O across a plasma membrane down a [free H2O] gradient.; Water movement facilitated by aquaporinsWater permeability can be regulated[free H2O] α 1 / [solute]
Osmosis
66
T/F: Water molecules will move passively down free water gradient (toward the area with a higher solute conc.)
True
67
Does osmotic equilibrium always equal volume equilibrium?
No
68
T/F: Osmosis is substance specific
False
69
Only _____ substances determine water movement via osmosis
impermeable
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The total (free) solute concentration of a solution is known as its _____ (permeable and impermeable solute).
osmolarity
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One ____ is equal to 1 mol of solute particles
osmol
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1 M solution of glucose has a concentration of ____ Osm (osmol per liter), whereas a 1 M solution of sodium chloride is ____ Osm ( osmol of solute per liter of solution).
1 Osm; 2 Osm
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bathing solution Osm = cytosolic Osm2.
Isosmotic
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bathing solution Osm < cytosolic Osm3.
Hyposmotic -
75
bathing solution Osm > cytosolic Osm
Hyperosmotic -
76
defined by the number of impermeable substances only; determines the direction of H2O movement via Osmosis
Tonicity
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Concentration of impermeable solute = cell cytosol2. Cells in this bathing solution will have no net Δ volume
Isotonic solution
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Concentration of impermeable solute < cell cytosol2. Cells in this bathing solution will gain water and swell
Hypotonic solutions
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Concentration of impermeable solute > cell cytosol2. Cells in this bathing solution will lose water and shrink
Hypertonic solutions
80
_____ is the pressure required to stop the flow of water in to a compartment
Osmotic pressure
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Ethanol, fatty acids, O2, CO2, steroids, Urea, and glucose are ____ solutes (permeable or impermeable)
Permeable
82
Ions and proteins are ____ solutes (permeable and impermeable)
Impermeable
83
Urea and glucose are ____ on the cellular level but _____ on the systemic level and RBC
Impermeable on cellular; permeable on systemic
84
Water is the most abundant molecule in your body accounting for _____ % of body weight
60%
85
How much of body weight is due to water in ICF?
40%
86
How much of body weight is due to water in interstitial fluid?
15%
87
How much of body weight is due to water in blood plasma?
5%
88
The volume of water in the intracellular vs. extracellular spaces is ______.
unequal
89
The osmolarity of the extracellular and intracellular spaces is _____.
equal
90
_____ requires an input of energy
Active transport
91
Transmembrane protein that moves ions and hydrophilic building blocks across the plasma membrane up a ΔC (requires energy); Classification Based on: Number of substances being transported, Directions substances are transported, and Source of energy for transport
Active transporters
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Active transport that transport only one of substrate
Uniport
93
Moves more than one substance and all substances moving in same directions
Symporters
94
Moves more than one substance and all substances moving in different directions
Antiporters
95
In ______ active transport, energy comes directly from breakdown of ATP
Primary (1°) Active
96
In ______ active transport, energy released from one substance moving down a gradient is used to pump a second substance up a gradient.
Secondary (2°) Active
97
____ active transport moves 1 substance up a gradient and 1 down
Secondary active
98
_____ Moves large substances across plasma membrane, Gradient Independent, and Requires Energy; how cell modifies composition of plasma membrane
Vesicular Transport
99
Brings substances into cell•Forms vesicle•Removes membrane from Plasma Membrane
Endocytosis
100
Removes substances from cell•Vesicle fuses to membrane•Adds membrane to Plasma Membrane
Exocytosis
101
Plasma has more _____ than interstitial fluid making it different
protein
102
Charge difference across the plasma membraneCreated by unequal distribution of anions and cations across the cell membraneCharge separation = source of energy
Membrane potentials (Vm)
103
_____ is the charge difference across the plasma membrane when the cell is at rest.
Resting Membrane Potential
104
What is normal resting membrane potential
-70 mV
105
The sign of the membrane potential represents the charge ____ the cell
inside
106
Creates electrical gradients for movement of ions into/out of cells; Opens or closes gated ion channels; Regulates exocytosis.
Membrane potentials
107
In ____ gradient, Ions will move passively down concentration gradients
Chemical Gradient
108
In ____ gradient, ions will move passively down electrical gradients
Electrical gradients
109
____ gradient is characterized by FDRIon = (ΔEC)(T)(#ion channels)(Popen)
Electrochemical Gradient
110
_____ OF THE ELLECTRICAL GRADIENTDepends on the valence of the ion and the magnitude of the membrane potential.
STRENGTH
111
Vm that creates an ΔE that is equal in strength but opposite in direction of the ΔC (ΔE-ΔC=0).Electrochemical EquilibriumNo net ion movement through channels via facilitated diffusion
Equilibrium Potential (Eion) =
112
Calculates the equilibrium potential (E) when ion concentrations are known.
The Nernst Equation
113
What is the formula for Nernst Eq?
Eion (mV) = (61/Z) log ([ion]ECF / [ion]ICF)
114
T/F: At a cell’s resting membrane potential, the equilibrium potentials for Na+, K+, Cl- & Ca++are such that when an ion channel for one of these ions opens, the ions follow their concentration gradient.
True usually
115
Vm becomes less negative than rest.
Depolarization –
116
Vm change that restores resting Vm.
Repolarization –
117
Vm becomes more negative than rest
Hyperpolarization –
118
T/F: When Ion moves down EC gradient, Vm moves toward Eion, decreasing the EC gradient for ion movement and subsequently decreasing rate of ion movement via facilitated diffusion.
True
119
What are the 2 determinants of resting membrane potential?
Relative ion permeabilities and Na/K ATPase activity
120
To change _______, Change the membrane’s permeability to an ion (open/close a channel, or change activity of an active transporter); Change the ion concentration gradient across the membrane
Membrane potential
