unit 4
Terms
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- endocrine signals
- hormonal, long distance. signal released travels through blood vessels to target cell, affects only target cell with correct receptor
- amphipathic
- molecule that has both a hydrophilic region and a hydrophobic region such as a phosopholipid
- isotonic
- the solute concentration is the same on both sides
- diffusion
- passive movement of a substance from an area of high concentration (or activity) to low concentration dur to the random motion of its particles; always toward equilbrium
- freeze fracture microscopy
- freeze a collection of membranes, fracture them with a dull blade. prepare the fractured surfaces for scanning, electron microscope
- peripheral protein
- stick on surface of membrane but do not embed within
- endocytosis
- the cellular uptake of macromolecules and particulate substances by localized regions of the plasma membrane that surround the substance and pinch it off to form an intracellular vesicle using cellular energy
- signal transduction pathway
- mechanism linking a mechanical or chemical stimulus to a specific cellular response
- fatty acid
- a long carbon chain carboxylic acid. fatty acids vary in length and in the number and location of double bonds; three fatty acids linked to a glycerol molecule form fat.
- glycerol
- three carbons with a hydroxyl; eliminating hydrophobia, component of phospholipids
- passive transport
- simple diffusion and facilitated osmosis/diffusion-downhill, losing free energy, end with less free energy
- osmosis
- diffusion of water across membranes, most water movement is facilitated diffusion through membrane-bound water channel proteins called aquaporins. solutes affect the net direction of movement. always toward the side of the memebrane where solutes are more concentrated
- active transport
- use of transport proteins and cellular energy to move against the concentration gradient; moves molecules or ioins across membranes using transport proteins; cell supplies the energy in the form of ATP; the carrier proteins are unidirectional and called pumps
- plasmolysis
- due loss of water in a hypertonic solution the membrane pulls away from the cell wall
- glycoprotein
- a protein covalently attached to a carbohydrate
- cholesterol
- steroid that forms an essentail component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids
- transport protein
- allow diffusion of hydrophilic substances, called channels or carriers; used in facilitated diffusion
- integral protein
- typically a transmembrane protein with hydrophobic regions that completely spans the hydrophobic region of the interior of the membrane
- hypertonic
- the side with more solute, making a cell shrivel, loose water, water moves to hypertonic side
- pinocytosis
- type of endocytosis where liquids are "drank" using smaller vesicles
- selective permeability
- membranes control the types of substances that can cross, the rate of transport, the direction of transport. they are also dynamic meaning their transport properties can change
- receptor-mediated endocytosis
- give endocytosis specificity derived from a protein controlled process; movement of specific molecules into a cel by the inward budding of membranous vesicles containing proteins with receptor sites specific to the molecules being taken in; enables a cell to acquire bulk quantities of specific substances
- exocytosis
- the cellular secretion of macromolecules by the fusion of vesicles witht he plasma membrane using cellular energy
- paracrine signals
- target cells nearby the signal releasing cell
- turgid
- very firm, a walled cell becomes this if it has a greater solute concentration than its surroundings, resulting in entry of water
- gated channel
- a protein channel in a cell membrane that opens or closes in response to a particular stimulus
- neurotransmittors
- a chemical messenger released from teh synaptic terminal of a neuron at a chemical synapse that diffuses across the synaptic cleft and binds to and stimulates the postsynaptic cell
- cotransport
- the coupling of downhill diffusion of one substance to the uphill transport of another against its own concentration gradient
- aquaporin
- a transport protein in the plasma membrane of a plant or animal cell that specifically facilitates the diffusion of water across the membrane (osmosis)
- electrogenic pump
- an ion transport protein that generates voltage across a membrane
- fluid mosiac model
- proteins are embeded in the phospholipid bilayer and can move laterally within
- phospholipid
- molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail. consists of five smaller building blocks attached by dehydration reactions
- sodium-potassium pump
- found in every animal; Na out of the cell, K into the cell, both normally against concentration gradient
- electrochemical gradient
- the diffusion gradient of an ion, representing a type of potential energy that accounts for both the concentration difference of the ion across a membrane and its tendency to mvoe relative to the membrane potential
- lipid
- a class of macromolecules. mostly hydrocarbon, largely nonpolar-hydrophobic, not soluble in water, three most important to living systems are fats, phospholipids and steroids
- signal receptors
- on the surface of cells where the signal must attach
- phagocytosis
- type of endocytosis where soilds get encorporated into the cell
- phospholipid bilayer
- the hydrophilic heads are on the outside in the water and the hydrophobic tails point inside