Membrane Transport Flashcards
The boundary between the cells intracellular spaces and the extracellular matrix
Cell membrane
What is the permeability of the Plasma Membrane?
Differentially(selectively) permeable
Factors that determine how a substance may be transported across the plasma membrane
- Size
- Polarity (polar/non-polar)
- Solubility
Governs all biological systems. “Universe tends towards disorder(entropy). Movement from high to low concentration
2nd Law of Thermodynamics
Diffusion of small, relatively hydrophobic molecules across a phospholipid bilayer at significant rates.
Passive Diffusion
Molecules that can diffuse through the plasma membrane
Gases, Water molecule, Lipids, lipid soluble molecules, Small non-charged molecules
Diffusion with the aid of proteins that do not interact with the hydrophobic interior
Facilitated Diffusion
Diffusion used by biological molecules that are unable to dissolve in the hydrophobic interior. No energy needed
Facilitated Diffusion
Facilitated = __________
Open Channel = __________
With help
fast transport
Passage of materials aided by both a concentration gradient and a transport protein
Facilitated Diffusion
Protein that transport glucose in and out of the cell. Mostly found on erythrocytes.
Glucose Transporters
Two kind of transport proteins:
- Carrier Proteins
- Channel Proteins
Bind specific molecules, undergo conformational change to release molecule.
Carrier Proteins
Transport protein that form open pores for free diffusion, found in gap junctions
Channel Proteins
Bond and drag molecules through the lipid bilayer and releases them on the other side.
Carrier proteins
Channel Proteins allow:
ions, small solutes, and water
Facilitated Diffusion is limited due to:
Presence of protein channels
Carrier proteins allows:
glucose and amino acids
Functions of Facilitated Diffusion
- Food for cell respiration
- Communication of neurons
- Small intestine food transport to the bloodstream
- Muscle cells contract
Protein corridors that allow the fast movement of water molecules across the membrane.
Aquaporins
Protein pores used by the cells during Osmosis
Aquaporins
Diffusion of water across a differently permeable membrane
Osmosis
Pressure that develops in a system due to osmosis
Osmotic Pressure
Different concentrations of water
- Hypertonic
- Isotonic
- Hypotonic
Equal water and solution mixture
Isotonic
Less solute, more water
Hypotonic
More solute, less water
Hypertonic
Animal cell and plant cell state when force in a hypotonic solution
Lysed, Turgid
State of animal cells and plant cells in an isotonic solution:
Normal, Flaccid
State of animal cells and plant cells in a hypertonic solution
Shriveled, Plasmolyzed
Organelle that pumps the water out of the cell with the help of ATP
Contractile Vacuole
A unicellular organism that live constantly on Hypotonic state of water
Paramecium cells
Molecules that passively diffuse down their electrochemical gradient through channels that cross the lipid bilayer.
Non-lipid soluble substances
Regulates the opening and closing of voltage gated channels:
Membrane Potential
Voltage regulates the opening and closing of ____________ channel
Voltage-Gated Channel
Gated channel that activates to a stimuli created by ligand
Ligand-Gated Channel
Gated channel proteins that act to a specific stimuli
Specific-Activated Channels
Permits the passage of ions and small polar molecules through the membranes of bacteria
Porins
Mediates the passage of ions across plasma membranes
Ion channels
Channels that open in response to the binding of neurotransmitters or other signaling molecules
Ligand-Gated channels
Channels that open in response to changes in electric potential across the plasma
Voltage-gated channels
Protein channels that open or close depending on the presence or absence of physical or chemical stimulus (released by neurotransmitters)
Gated Channels
if not present, the gated channels are closed
Neurotransmitters
Diffusion that allows molecules to move against the concentration gradient
Active Transport
Importance of Active Transport
- Brings essential molecules
- Rid cells of unwanted molecules
- Maintain internal conditions
- Regulate cell count
- Re-establish concentration gradient
2 groups of active transport
- Primary Active Transport
- Secondary Active Transport
Active transport that uses ATP to stimulate the protein that moves substances against the concentration gradient from an area of low to high concentration
Primary Active Transport
Active transport that uses two channel proteins and the energy of a molecule that diffuses passively to move another molecule against the concentration gradient.
Secondary Active Transport
Class of Secondary Active Transport that moves two molecules in the same direction across a concentration gradient
Symporter
A secondary molecule utilizes the energy from a primary molecule that diffuses passively to move to a similar direction
Symporter
Two substances move against each other across the plasma membrane
Antiporter
One of the substance moves passively down its concentration gradient while the second substance uses ATP to move against its concentration gradient across the plasma membrane.
Antiporter
Transporter that can only transport a single molecule using facilitated diffusion of glucose
Uniporter
Cotransport proteins:
Symport and Antiport
Transports of molecules outside the cell and keeps macromolecules contained
Vesicle Formation
Formation of vesicles as a way to transport molecules out of the cell
Exocytosis
The substances that are transported by exocytosis
Neurotransmitters, hormones, and digestive enzymes
This is how many hormones are secreted and how nerve cells communicate with each other
Exocytosis of proteins
Vesicles form as a way to transport molecules into the cell
Endocytosis
Endocytosis of Large particulate matter (e.g. Bacteria, viruses, or dead cells) also known as “Cell Eating”
Phagocytosis
Endocytosis of liquids and small particles dissolved in liquid (cell drinking).
Pinocytosis
Ligand-receptor complexes triggers infolding of a clathrin pit that forms a vesicle containing ligands such as: vitamins, hormones, and anti-bodies
Receptor Mediated Endocytosis
Most common form of endocytosis. Materials dissolved in water to be brought into the cell.
Pinocytosis
Vesicles that are used to move molecules inside the cell are coated with the protein ________
Clathrin
A form of pinocytosis, provides a mechanism for the selective uptake of specific macromolecules.
Receptor mediated endocytosis
Specialized regions of the plasma membrane where specific cell receptors are found
Clathrin-coated pits
A membrane associated with GTP-binding protein that assists the budding off of the pits from the plasma membrane
Dynamin
Clathrin-coated pits occupy about ________% of the surface area of plasma membranes
1% - 2%
Vesicles with tubular extensions located at the periphery of the cells that fuse with clathrin-coated vesicles.
Endosomes
Maintains the acid internal pH caused by the action of a membrane H+ pump.
Endosomes
A phenomenon where receptor-ligand complexes are removed from the plasma membrane, terminating the response of the cell to growth factor stimulation
Receptor-down regulation
Phagosomes that infused fused to lysosomes, contains lysosomal acid hydrolases that digest ingested material.
Phagolysosomes
Moves chlorine ions outside of the cell
CFTR Channels
Disease caused by the failure of CFTR channels to pump chlorine out of the cells that leads to the build-up of sticky mucus on the outside of the cell
Cystic Fibrosis
Cystic Fibrosis can be passed through?
Genetics/Trait Inheritance
