Chapter 7 (The Cell Membrane) Flashcards
what are the two names for the plasma membrane?
fluid mosaic model or phospholipid bilayer
Why is the plasma membrane called the fluid mosaic model?
proteins embedded into it, the membrane that is able to move (semi-fluid), made of phospholipids
Which one moves faster, lipids or proteins? (contributes to fluidity in the plasma membrane)
lipids
What is the most abundant type of lipid?
phospholipids
In a phospholipid, what is the hydrophilic part?
the head
o
II
In a phospholipid, what is the hydrophobic part?
tail
The outer part of the membrane is what charge?
it is neutral
When talking about the outer membrane in relation to the inner membrane, what is the charge of the outer membrane?
positive
What is the charge on the inner side of the plasma membrane?
negative
Are the arrangements of the phospholipids in the plasma membrane symmetrical or asymmetrical?
asymmetrical
What is in between the gaps from the asymmetry of the plasma membrane?
cholesterol
What are the two phases that the plasma membrane goes through in terms of temperature?
fluid phase and gel phase
The fluidity of the cell membrane depends on what?
hydrocarbon chains
What is cholesterol for in the cell?
critical for maintaining the fluidity of the cell (aka temperature buffer)
When the temperature is too warm for the cell, what does cholesterol do?
restrains the movement of the cell to prevent the pulling apart of molecules
When the temperature is too cold for the cell, what does cholesterol do?
prevents compaction
What are the classes of proteins in the plasma membrane?
integral (integrin) proteins and peripheral proteins
What are integral proteins?
they are proteins that are stuck in the membrane
What shape do integral proteins use to anchor themselves into the lipid bilayer?
the alpha-helix (spiral)
In integral proteins, what kinds of passes do they make?
single passes and multiple passes
What are single-pass integral proteins?
they look like 1 spiral embedded, they anchor
What are multi-pass integral proteins?
they are many spirals together that are embedded, they created channels
What quality do proteins have in terms of water?
they are amphipathic (both hydrophilic and hydrophobic)
What are peripheral proteins?
they are proteins bound to a single surface
If the peripheral protein is bound on the outside, what do they associate with?
the ECM (extracellular matrix)
If the peripheral proteins are bound on the inside, what do they associate with?
the cytoskeleton of the cell
Is the plasma membrane permeable or semi-permeable
semi-permeable
What types of materials easily cross the plasma membrane?
hydrophobic materials
What are some examples of hydrophobic materials that pass through the plasma membrane?
hydrocarbons, gases, small molecules
What types of materials are slow to cross (or don’t cross at all) the plasma membrane?
hydrophilic materials
What are some examples of hydrophillic materials that are slow to cross (or don’t cross) the plasma membrane?
ions, nutrients, large molecules
What is passive transport?
doesn’t use energy to diffuse
What is an example of passive transport?
diffusion
What is diffusion?
the tendency for molecules to go from a high concentration to a low concentration
What is dynamic equilibrium?
equal movement of particles, 0 net movement
What is osmosis?
diffusion of water across a selectively permeable membrane
What is osmosis dependent on?
solute concentration
What is the pattern for osmosis?
water molecules flow from low to high solute concentration in order to disperse the solute
Does osmosis need energy?
no
Does diffusion need energy?
no
What is an isotonic solution?
solute concentration on the inside and outside the cell is the same
What are hypertonic solutions?
solute concentration is higher on the outside so the water from the cell goes outside and shrivels up
What are hypotonic solutions?
solute concentration higher on the inside of the cell, making water go inside and the cell bursting due to too much water (lysed)
What is osmoregulation?
control of water balance
What is facilitated diffusion?
transport proteins use for passive movement
Does facilitated diffusion need energy
no
What are the types of facilitation proteins in facilitated diffusion?
channel proteins and carrier proteins
What are channel proteins?
corridors for a specific molecule or ion to cross that require a stimulus to open/close
What kinds of stimuli do channel proteins need to open and close?
chemical (ligand), mechanical (stress), or electrical (voltage)
What are carrier proteins?
no energy needed proteins change protein shape due to conformation
What does the cell generate when it harbors certain solutes?
generates potential energy, storing energy
What is the result of ion transport?
membrane potential created due to voltage difference across a membrane that results from asymmetrical lipids in the plasma membrane
What is the electrochemical gradient?
it drives the diffusion of ions across a membrane
In the electrochemical gradient, what is the chemical force?
ion gradient
In the electrochemical gradient, what is the electrical force?
it is for neutralization which comes about due to the effect of the membrane potential on ion molecules
What are examples of processes in the cell that uses electrogenic pumps?
sodium/potassium pump and proton pump
What is active transport?
moving solutes AGAINST the concentration gradient
Does active transport need energy?
YES
Where does active transport get the energy?
by breaking down ATP to ADP
What is it called when the membrane uses ATP for transfer across a membrane?
phosphorylation
What does active transport do?
allows cells to maintain solute concentrations to that differ from surroundings
What are the types of active transport?
indrect and direct active transport
What is direct active transport?
uses ATP directly in the proteins
What is an example of direct active transport?
sodium/potassium pump
What is indirect active transport?
uses energy indirectly
What is an example of indirect active transport?
cotransport
What is cotransport?
uses one solute’s gradient to drive against it own gradient through the use of ions
What is symport cotransport?
same direction of ion and molecule traveling through protein
What is antiport cotransport?
opposite directions of ion and molecule traveling through protein
What is coupled transport?
when multiple proteins are working together for a common good (like many people working to build a house)
What is bulk transport for?
necessary for large molecules to get in/out of the cell
What are the types of bulk transport?
exocytosis, endocytosis (via phagocytosis, pinocytosis, or receptor-mediated)
What is exocytosis?
leaving the cell, when internal vesicles fuse with the membrane in order to release content outside (like toxins)
What is endocytosis?
entering the cell
What is phagocytosis?
movement of the membrane to engulf a foreign particle to bring into the cell
What is pinocytosis?
depression made with membrane to pull in particle
What is receptor-mediated endocytosis?
chemical signaling (like lock and key, ligand and protein) protein coats the vesicles once inside the cell
