Chapter 5, 6, 7 Flashcards
Selective Permeability
Allows some substances to move across more easily than others
Amphipathic
Has both a hydrophobic region and hydrophilic region
Fluid Mosaic Model
Membrane is a mosaic of protein molecules bobbing in a fluid bilayer of phospholipids
The membrane remains fluid at lower temperature if it is rich in _________
Phospholipids with unsaturated hydrocarbon tails
Kinks in the tails where the double bonds are located make it impossible to pack closely together
Integral Proteins
Penetrate the hydrophobic interior of the lipid bilayer.
Transmembrane Protein
Span the entire membrane
Peripheral Protein
Are not embedded in the lipid bilayer at all; they are loosely bound to the surface of the membrane.
6 major functions of membrane proteins
Transport Enzymatic Activity Signal Transduction Cell-Cell Recognition Intercellular Joining Attachment to the cytoskeleton and extracellular matrix
The Elephant Shits Cranberries In Alabama
Cell Cell Recognition
A cells ability to distinguish one type of neighboring cell from another
Glycolipids
Membrane carbohydrates that are short branched chains of fewer than 15 sugar units covalently bonded to lipids
Glycoproteins
Membrane carbohydrates bonded to proteins
Nonpolar molecules such as hydrocarbons, CO2, and O2 are _________and dissolve in the ___________ of the membrane and cross it easily.
Hydrophobic, lipid bilayer
Transport proteins
Span the membrane and aid in the movement of specific ions and polar molecules
Channel Proteins
Function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel
Aquaporins
A channel protein that facilitates the passage of water molecules through the plasma membrane of certain cells.
Carrier Proteins
Hold onto their passengers and change shape in a way that shuttles them across the membrane.
Passive transport
Diffusion of a substance across a membrane with no energy investment
Diffusion
The movement of particles of any substance so that they tend to spread out into the available space.
Osmosis
The diffusion of free water across a selectively permeable membrane
Tonicity
The ability of a surrounding solution to cause a cell to gain or lose water.
Isotonic Solution
No net movement of water across plasma membrane
Hypertonic
Cell shrivels as water leaves due to more no penetrating solute
Hypotonic
Water will enter the cell and bursts or lyse
Plant cells are ________ and generally healthiest in a __________environment
Turgid, hypotonic
Plants are flaccid in a ________ solution
Isotonic
Plants become _____________ in a hypertonic solution
Plasmolyzed
Plasmolysis- plasma membrane pulls away from cell wall.
Osmoregulation
The control of solute concentrations and water balance
Facilitated Diffusion
Passive diffusion with the help of transport proteins that span the membrane
Ion channels
Channel proteins that transport ions
Gated channels
Ion channels which open or close in response to a stimulus
Active transport
Expending energy to move something across membrane
Hydrophobic and small uncharged polar molecules can pass through the lipid bilayer through
Passive diffusion
Hydrophilic substances diffuse through membranes with the assistance of
Transport proteins, either channel or carrier proteins
Energy for active transport is usually supplied by
ATP
Membrane potential
Voltage across a membrane
Electrochemical gradient
The combination of electrical and chemical forces acting on an ion
Electrogenic pump
A transport protein that generates voltage across a membrane
Proton pump
The main electrogenic pump of plants, fungi, and bacteria
Cotransport
A transport protein can couple the downhill diffusion of a solution to the uphill transport is a second substance against its own concentration gradient
Exocytosis
The process in which the cell secretes certain biological molecules by the fusion of vesicles with the plasma membrane
Endocutosis
The process where a cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane
3 types of endocytosis
Phagocytosis-cell engulfs a particle by extending pseudopodia around it and packaging it within a food vacuole
Pinocytosis-a cell continually gulps droplets of extracellular fluid into tiny vesicles
Receptor mediated endocytosis-specialized type of pinocytosis where specific substances are acquired
3 stages on the receiving cell
Reception
Transduction
Response
Ligand
A molecule that specifically bonds to another molecule
Plasma membrane is built by the
ER and Golgi apparatus
Two types of facilitated diffusion
Channel proteins and carrier proteins
Two types of channel proteins
Aquaporins and ion channels
Paracrine signaling
Local signaling in animal cells where messenger molecules are secreted by a signaling cell
Synaptic signaling
Consists of an electrical signal moving along a nerve cell that triggers secretion of neurotransmitter molecules
In long distance signaling, plants and animals use chemicals called
Hormones
Ligand binding generally causes a shape change in the
Receptor
Two types of membrane receptors
G protein coupled receptors
Ligand Gated ion channels
Examples of hydrophobic messengers
Steroid and thyroid hormones of animals and nitric oxide in both plants and animals