Lecture 2: Membranes, Channel, and Transport Flashcards
(167 cards)
1
Q
• separates the cytoplasm from the external environment
A
Cell membrane
2
Q
•one of the most important cell organelles
• a highly selective permeable barrier thatsurrounds all living cells
A
Cell membrane
3
Q
• controls how molecules and compounds move in and out of the cell
• very important for proper nutrition, maintenance of irritability of the cells, and homeostasis
A
Cell membrane
4
Q
Cell membrane is very important for_____, ____, and _____
A
proper nutrition, maintenance of irritability of the cells, and homeostasis
5
Q
Cell membrane significance:
A
• define boundaries and serve as permeability barriers
• compartmentalization (for organization and localization of specific functions)
• signal detection
• cell-to-cell communication
6
Q
•lipid-based structure
that encloses the cytosol
A
Cell membrane
7
Q
Cell membrane is a ____ structure that encloses the cytosol
A
lipid-based
8
Q
Cell membrane sustain different concentrations of certain ions on their two sides, leading to ______
A
concentration gradient
9
Q
In cell membrane ____ participates in the transport of substances
A
Protein
10
Q
-Describes the organization of cell membranes
A
The Fluid Mosaic Model
11
Q
The ____ is a mosaic mixture of phospholipids, steroids, proteins, and other molecules
A
bilayer
12
Q
The bilayer is a mosaic mixture of ___, ___,___, and ____
A
phospholipids, steroids, proteins, and other molecules
13
Q
The cell membrane is composed of ____, ____, _____ arranged in a fluid mosaic structure.
A
phospholipids, proteins, and carbohydrates
14
Q
The cell membrane is composed of ____ and ____ kept together by non-covalent interactions
A
lipid and protein molecules
15
Q
cell membrane is composed of lipid and protein molecules kept together by ______
A
non-covalent interactions
16
Q
Most of their lipid and protein molecules “float” in the plane of the ____
A
bilayer
17
Q
– impermeable to the passage of most water-soluble molecules
A
Lipid bilayer
18
Q
It is fundamental structure of the membrane
A
lipid molecules
19
Q
It is a kind of protein that usually span from one side of the phospholipid bilayer to another
A
Integral protein
20
Q
It is the kind of protein that can sit on the surface of the membrane
A
Peripheral protein
21
Q
-can slide around the membrane very quickly and collide with each other, but seldom flip from one side to the other
- responsible for most of the membrane’s properties
A
Proteins
22
Q
Type of protein that is embedded in the lipid bilayer provide a mechanism for trans-membrane transport
A
Integral proteins
23
Q
Examples of integral protein
A
- passive-transport pores and channels
2.active-transport pumps - carriers
- membrane- linked enzymes,
- chemical signal receptors
- transducers
24
Q
Examples of integral protein
A
- passive-transport pores and channels
2.active-transport pumps - carriers
- membrane- linked enzymes,
- chemical signal receptors
- transducers
25
- associated with the surface of the membrane via electrostatic interaction
Peripheral proteins
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inside surface maintain cell shape or cell motility
Protein
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-catalyzing reactions in the cytoplasm.
enzymes
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Protein can act as a _____( specific binding site where hormones or other chemicals can bind)
Receptors
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-Used as cell signaling and cell recognition
protein
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Proteins in the plasma membrane may provide a variety of major cell functions such as
1. transport
2. enzymatic activity
3. signal transduction
4. intercellular joining
5.cell- ell recognition
6. attachment to cytoskeleton to ECM
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Special function of proteins
1. Adhesion proteins
2. Recognition proteins
3. Receptor proteins
4. Enzymes
5. Transport proteins (active and passive)
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-clumping of blood
Agglutination
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Type O blood has no ____
antigen
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Type O blood has both ____ anti bodies
A and B
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The serum used in blood typing (consists of anti bodies)
Antisera
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If the recipient is Rh+, you can donate if you are ___
Rh+ and -
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If the recepient is Rh-, you can donate if you are ___
Rh-
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Rh- mother and Rh + baby
compatible at first but no longer applicable for second child since the antibodies of the mother can now recognized the foreign substance which is the blood of Rh+ baby
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found on the outer surface and attached to the proteins or sometimes to the phospholipids
Carbohydrates
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Carbohydrates is found on the ____ and attached to the proteins or sometimes to the phospholipids
outer surface
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Examples of carbohydrates
Glycoproteins and glycolipids
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It form a cell coat or glycocalyx outside the cell membrane
Carbohydrates
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form a cell coat or glycocalyx outside the
cell membrane
Carbohydrates
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protection and cell
recognition
glycocalyx
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____ bear oligosaccharide side chains and are vital for cell recognition and communication
Glycoprotein
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Primary types of Lipids
1. Phosphoglycerides
2. Spingolipids
3. Sterols
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It is the glycerol backbone
Phosphoglycerides
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Its backbone made of sphingosine bases
Spingolipids
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Its backbone made of sphingosine bases
Spingolipids
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They are the cholesterol, nonpolar and only slightly soluble in water
Sterols
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They are the cholesterol, nonpolar and only slightly soluble in water
Sterols
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phosphoglycerides and sphingolipids are _____
amphipathic
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phosphoglycerides and sphingolipids are _____
amphipathic
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Amphiphatic is _____
one end is hydrophilic, and the other is hydrophobic
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Amphiphatic is _____
one end is hydrophilic, and the other is hydrophobic
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differences in the lengths of
the two fatty acid tails and their composition influence ____
fluidity
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depends on its composition and ____ (binds weakly to phospholipids making the membrane less fluid but stronger)
cholesterol
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membrane molecules are held in place by relatively weak ___
hydrophobic interactions
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most lipids and some proteins can drift ____ in the plane of the membrane, but rarely ____ from one layer to the other.
laterally; flip- flop
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The ____ temperature, the fluid state become solid. Phospholipids become compact
lower
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At warm temperatures, the ____ restrain the movement of the phospholipid and. reduce fluidity
steroid cholesterol
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_____, it restrains the movement of phospholipids and reduces fluidity
at warm temperatures
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at______, steroid cholesterol maintains fluidity by preventing tight packing
cool temp
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membrane show the progressive removal of proteins when subjected to digestion with ____
proteolytic enzyme
65
_____ splits a membrane along the middle of
the phospholid bilayer prior to electron microscopy.
Freeze fracture
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______ shows protein particles interspersed with a smooth matrix, supporting the fluid mosaic model.
freeze fracture
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Due to the Cell membrane ______, it regulates the passage of materials (gases, nutrients, wastes) in and out of the cell
Selective permeability
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The ____ makes membranes highly impermeable to most polar molecules
hydrophobic interior
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2 types of transport system
1. Passive Process
2. Active transport
70
- no energy expenditure and move down their normal gradient
Passive process/transport
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Example of passive process
• simple diffusion/lipid diffusion
• osmosis
• facilitated diffusion/passive Transport
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• requires metabolic energy and moves
substances against their gradients
Active Transport
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• requires metabolic energy and moves
substances against their gradients
Active Transport
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the 3 basic route in passive transport
1. Dissolving in the lipid phase
2. Diffusion through labile or fixed aqueous channels
3. Carrier-mediated transport (facilitated or active transport)
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In this route, the molecules diffuse through the membrane.
-dissolves directly in the lipid bilayer
- diffuses across the thickness of the lipid or protein layer
-enters the aqueous phase on the opposite side
1. Dissolving in the lipid phase
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* solute molecule remains in the aqueous phase
* diffuses through aqueous channels (water-filled pores in the membrane)
2. Diffusion through labile or fixed aqueous channels
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- solute molecule remains in the aqueous phase
- diffuses through aqueous channels (water-filled pores in the membrane)
Diffusion through labile or fixed aqueous channels
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- solute molecule combines with a carrier molecule dissolved in a membrane
- carrier “mediates” or “facilitates” the movement of the solute molecule across the membrane
3. Carrier-mediated transport (facilitated or active transport)
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- random thermal motion of suspended or dissolved molecules causes their dispersion from regions of higher concentration to regions of lower concentrations
Diffusion
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- random thermal motion of suspended or dissolved molecules causes their dispersion from regions of higher concentration to regions of lower concentrations
Diffusion
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- Net movement of particles (atoms, molecules, or ions) along a concentration gradient from an area of higher concentration to an area of lower concentration
Diffusion
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- Net movement of particles (atoms, molecules, or ions) along a concentration gradient from an area of higher concentration to an area of lower concentration
Diffusion
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Diffusion is the net movement of molecules from _____ to ____
high concentration to a lower concentration
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Diffusion is the net movement of molecules from _____ to ____
high concentration to a lower concentration
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In the absence of other forces, a substance will diffuse from where it is ____ to where it is _______ (down its concentration gradient).
more concentrated ; less concentrated
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diffusion of a substance across a biological membrane is _____(exergonic)
passive transport
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This protein assist molecules with limited permeability to diffuse through the lipid bilayer
Transport proteins
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This protein assist molecules with limited permeability to diffuse through the lipid bilayer
Transport proteins
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______ of a membrane to a substance is the rate at which that substance passively penetrates the membrane under a specified set of conditions.
permeability
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a few substances can diffuse directly through the lipid bilayer part such as the ______
lipid-soluble molecules such as steroids, or very small molecules, such as H2O, O2 and CO2
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The rate of diffusion depends on five factors such as
◦ Size
◦ Temperature
◦ Steepness of the concentration gradient
◦ Charge
◦ Pressure
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In lipid solubility, high mobility means ___ lipid solubility
high
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Hydrogen bond with water - ____ mobility with high hydrogen bond with water
low
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Factors that influence mobility of solute molecule
1. Lipid solubility
2. Hydrogen bond with water
3. Molecular weight
4. Molecular shape
5. Partition coefficient
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Factors that influence mobility of solute molecule
1. Lipid solubility
2. Hydrogen bond with water
3. Molecular weight
4. Molecular shape
5. Partition coefficient
96
It is the diffusion of water across a selectively permeable membrane is a special case of passive transport
Osmosis
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It is the diffusion of water across a selectively permeable membrane is a special case of passive transport
Osmosis
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Osmosis continues until the solutions are ____
isotonic
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In ____, water moves from higher to lower water potential (down its concentration gradient)
Osmosis
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In osmosis, the movement of water can produce a _____ (a fluid mechanical pressure), resulting in a pressure gradient across a semipermeable membrane
hydrostatic pressure
101
_____ - pertains to solvent particles
Osmosis
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_______ the difference in hydraulic
pressures of a solution and water (interfacing one another at either side of an SPM) which must be overcome to prevent the entry of water into the solution across the membrane
osmotic pressure
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_____ - when two aqueous solutions exert
the same osmotic pressure through a
membrane permeable only to water.
Isosmotic
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_____ - if one solution exerts less
osmotic pressure than the other
Hypoosmotic
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_____ – if one solution exerts greater
osmotic pressure than the other
Hyperosmotic
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_____ - the concentration of a solution
expressed as the total number of solute particles per liter
Osmolarity
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_____ – response of cells or tissues
immersed in the solution
Tonicity
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_____ –osmotic pressure property of a solution
Osmoticity
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____ – no osmotic pressure difference between the cell and interior and the extracellular solution; no net water gain;
cell/tissue neither shrinks nor swell.
Isotonic solution
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*If the tissue swells because it absorbs water,
the solution is ______to the tissue
hypotonic
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*If the tissue shrinks because it loses water, the solution is _____ to the tissue.
hypertonic
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More water content means _____
turgid cells
113
Lesser water content means ____
plasmolyzed cells
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____ - hydrostatic pressure that puts cell walls in tension
Turgor Pressure
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The membrane of bacteria is attracted to the ___
hydrophobic tail present in soap
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- through transmembrane protein
Facilitated Diffusion/Passive Transport
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_____ tend to be specific for one
molecule, so substances can only cross a
membrane if it contains the appropriate
protein
transport proteins
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2 kinds of transport proteins
Channel and Carrier
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The water-filled pore or channel in the membrane allows _____ to diffuse across membranes
charged substances (usually ions)
120
_______ in the membrane
allows charged substances (usually ions) to
diffuse across membranes
water-filled pore or channel
121
Most channels can be ____ (opened or
closed), allowing the cell to control the entry
and exit of ions
gated
122
____ – small organic compounds
that specifically transports ions across
the plasma membrane
Ionophores
123
Types of ionophores
1. carrier ionophore
2. Channel-forming ionophore
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Some ______, ______open or close depending on the presence or absence of a physical or chemical stimulus.
channel proteins, gated channels
125
Types of gated channels
1. Voltage-gated
2. Ligand-gated (extracellular ligand)
3. Ligand-gated (intracellular ligand)
4. Stress-activated
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_____ –transports a single solute from
one side of the membrane to the other
Uniporters
127
Types of membrane channel
1. uniporters
2. Coupled transporters
128
Types of coupled transporters
1. symporters
2. Antiporters
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_____ - transfer one solute
and simultaneously or sequentially transfer a
second solute
Coupled transporters
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A coupled transporters that transfer solutes in the same direction
Symporters
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A coupled transporters that transfer solutes in opposite directions
antiporters
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the rate of influx ____ in proportion to
the concentration of the solute in the
extracellular fluid
increases
133
In ____ substance will bind on the side with higher concentration and be released at the lower concentration side
Diffusion through a carrier
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___ – require metabolic energy
and moves substances against their gradients
Active transport
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In active transport, the proteins are ____, different protein pump for
each molecule to be transported
highly specific
136
____ supplies the energy for
most active transport
ATP
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___ - actively maintains the gradient of sodium (Na+) and potassium
ions (K+) across the membrane
*Sodium-potassium pump
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Important Features of Active Transport
1. Transport can take place against substantial concentration gradient
2. Exhibit high degree of selectivity
3. ATP or other sources of energy are required
4. Certain membrane pumps exchange one kind of molecule or ion from one side of the membrane for another kind of molecule or ion from the other side
5.Some pumps perform electrical work by producing a net flux of charge
6. Selectively inhibited by specific blocking agents.
7. Energy is released by the hydrolysis of ATP by enzymes (ATPases) present in the membrane
139
____ - run on energy stored in
ion gradients
Symporter
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_____ Na+ /H+ antiporter in
the proximal tubule of the
mammalian kidney
Antiporters
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For each H+ expelled, one ____ is
taken up into the cell
Na+
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Lipid diffusion
no energy, protein, not specific. and not controllable
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osmosis
no energy, proteins, specific, not controllable
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passive transport
no energy, use protein, specific, controllablea
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active transport
use energy, use proteins, specific, controllable
146
* Small molecules and water enter or leave the cell through the ____ or by _____
lipid bilayer or by transport
proteins
147
Large molecules, such as polysaccharides and
proteins, cross the membrane via ___
vesicles
148
Movement across membranes
1. endocytosis
2. exocytosis
149
Examples of endocytosis
*Pinocytosis
*Phagocytosis
*Receptor-mediated
endocytosis
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____ - cell brings in macromolecules and
particulate matter by forming new vesicles from the plasma membrane
endocytosis
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______ ) - cell creates a vesicle around a droplet of extracellular fluid
◦ non-specific process
Pinocytosis (cellular drinking)
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cellular eating
Phagocytosis
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- Depends on the presence of receptor molecules embedded in the cell membrane
- triggered when extracellular substances bind to special receptors, ligands, on the membrane surface, especially near coated pits
Receptor-mediated endocytosis
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_____ - transport vesicle that
budded from the Golgi
apparatus is moved by
the cytoskeleton to
the plasma membrane
Exocytosis
155
Three main types
of intercellular
links:
1. tight junctions,
2. adhering junctions (zonula adherens,
desmosomes),
3. gap junctions
156
____ , type of a junction in which the membranes of adjacent cells are fused,
forming continuous belts
around cells
- it prevent leakage of extracellular fluid
across a layer of epithelial cells
Tight junction
157
- A type of junction that fasten cells together into strong sheets,
much like rivets
-reinforced by intermediate filaments of keratin
-attach muscle cells to each other in a muscle
Desmosome (anchoring junctions)
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Type of juntion that provide cytoplasmic channels between adjacent cells
- salt ions, sugar, amino
acids, and other small
molecules can pass
Gap junction (communicating junctions)
159
Osmotic properties of water
1. Ionic steady state
2. cell volume
160
____ – every cell maintains
concentrations of inorganic solutes inside the
cell that are different from those outside the cell
Ionic steady state
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Two ways to prevent osmotic swelling
a. pump water out as fast as it leaks in
b. pump out solutes that leak into the cell – major
mechanism for regulation of cell volume
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Membrane permeability to charged particles
depends both on the ____ and _____
membrane permeability
constant and on the electrical signal.
163
Two Forces can act on charged atoms and
molecules to produce a net passive diffusion of each species across a membrane:
1. chemical gradient
2. electric field
164
____ - arising from differences
in the concentration of the substance on the
two sides of the membrane
chemical gradient
165
____ - difference in electric potential
across the membrane
Electric field
166
* ion will move away from regions of ______ and it that ion is positively charged it will also move toward increasing negative
potential
high
concentration
167
