4. Cell Transport Across Membrane Pt.1 Flashcards
Anion/Cation
Anion: Negatively charged
Cation: Positively charged
Hydrophilic
water-loving; having an affinity for water; capable of interacting with water through hydrogen bonding
Ion
an atom or group of atoms that carries a positive or negative electric charge as a result of having lost or gained one or more electrons.
Inorganic ion
atoms (or groups of atoms) with an electric charge that do not contain carbon.
Organic molecule
molecules that are made of carbon and hydrogen, and can include other elements
Polar/non polar
Polar: different things at each end; positive and negative ends
Non-Polar: same ends
Protein conformational change
- induced by pH variation, temperature, effectors, etc
- shifts in the partition coefficient of the protein
Solute/solven/solution/Concentration
Concentration of solution: a measure of the amount of solute that has been dissolved in a given amount of solvent or solution
Water -soluble molecules
4-5 carbon atom rule: Molecules with fewer than 4-5 C atoms per hydrogen bonding group will likely be soluble in water. Molecules with more than 4-5 C atoms per hydrogen bonding group will likely be insoluble in water
Macromolecules
polymers, long chains of molecular sub-units called monomers
Specialized membrane
transport proteins
- Liposomes are impermeable to most water-soluble molecules
- ## cell membranes contain transport proteins
What is diffusion?
the movement of molecules in a fluid from areas of high concentration to areas of low concentration
Differences in the concentration of inorganic ions across a cell membrane create a membrane potential
- Electrical charges inside and outside are balanaced
Voltage Difference
Created by small excesses of positive or negative charge on the two sides of the plasma membrane
Membrane potential
voltage difference across the membrane
Resting Membrane Potential
Cell rest; the exchange of anions and cations across the membrane is steady
Two classes
of membrane proteins
Transporters and Channels
Transporters
transfer small organic molecules or inorganic ions
Channels
- form tiny hydrophilic pores and allow substances to pass by diffusion
- most channels are ion channels
Solutes transport
Passive or Active
downhill movement
Molecules flow from a region of high concentration to a region of low
concentration
Passive transport
Downhill movement is passive and requires no energy
Active transport
uphill movement requires energy
Osmosis
the diffusion of water across
membranes
Passive transporters
change conformation to mediate transport across the
membrane
Active transporters / Pumps
Movement of molecules or ions against their concentration and/or electrical
gradient
3 types of proteins for active transport
uniporters, symporters, or antiporters
3 types of energy sources are used in active transport
-ATP (used by primary active transporters)
-Electrochemical gradient (used by secondary active transporters)
-Light
Coupled transporters
- mediate coupled transport using electrochemical gradients
- secondary active
transporters
3 types of endocytosis
phagocytosis, pinocytosis, and receptor-mediated endocytosis
Receptor-mediated endocytosis
Specific uptake of large molecules (LDL uptake)
Pinocytosis (Cellular rinking)
cell takes in the fluids along with dissolved small molecules
Phagocytosis (cellular eating)
a cellular process for ingesting and eliminating particles larger than 0.5 μm in diameter
Exocytosis
secretory vesicles fuse with the plasma membrane and releases (secretes) its content into the extracellular space
