Chapter 5 (Membrane Structure and Function)

active transport

requires carrier protein; requires energy in form of ATP; goes against the gradient; never reaches equilibrium because it makes high get higher and low get lower

adhesion junction

junction between cells in which the adjacent plasma membranes do not touch but are held together by intercellular filaments attached to buttonlike thickenings

anchoring junction

junctions that mechanically attach adjoining cells (adhesion, tight, and gap junctions)

carrier protein

protein that combines with and trasnports a molecule or ion across the plasma membrane

cell recognition protein

glycoprotein that helps the body defend itself against pathogens

cell wall

structure that surrounds a plant, protistan, fungal, or bacterial cell and maintains the cell's shape and rigidity

concentration gradient

gradual change in chemical concentration from one point to another

differentially permeable

ability of plasma membranes to regulate the passage of substances into and out of hte cell, allowing some to pass through and preventing the passage of others

diffusion

movement of molecules or ions from a region of higher to lower concentration; it requires no energy and tends to lead to an equal distribution

endocytosis

cells engulf substances into pouch which becomes a vesicle

enzymatic protein

protein that catalyzes a specific reaciton

exocytosis

process in which an intercellular vesicle fuses with the plasma membrane so that the vesicle's contents are released outside the cell

faciliated transport (diffusion)

passive transfer of a substance into or out of a cell along a concentration gradient by a process that requires a carrier; can't get through membrane lipids; combine with carrier proteins and follow concentration gradient

fluid-mosaic model

model for the plasma membrane based on the changing location and pattern of protein molecules in a fluid phospholipid bilayer

gap junction

junction between cells formed by the joining of two adjacent plasma membranes; it lends strength and allows ions, sugars, and small molecules to pass between cells

glycolipid

lipid in plasma membranes that bears a carbohydrate chain attached to a hydrophobic tail

glycoprotein

protein in plasma membranes that bears a carbohydrate chain

hypertonic solution

concentration of solute higher than on other side; cells placed in this solution will shrink

hypotonic solution

concentration of solute lower than on the other side; cells placed in this solution will swell

isotonic solution

solute and water concentration equal on both sides of membrane

osmosis

diffusion of water through a differentially permeable membrane

osmotic pressure

measure of the tendency of water to move across a differentially permeable membrane; visible as an increase in liquid on the side of the membrane with high solute concentraion

phagocytosis

large, solid material go into vesicle

phospholipid bilayer

comprises the plasma membrane; each polar hydrophilic head is bonded to two nonpolar, hydrophobic tails; contains embedded protiens

pinocytosis

liquid or small, solid particles go into vesicle

plasmodesmata

in plants, cytoplasmic strands that extend through pores in the cell wall and connect the cytoplasm of two adjacent cells

plasmolysis

contraction of the cell contents due to the loss of water

recepter-mediated endocytosis

selective uptake of molecules into a cell by vacuole formation after they bind to specifric receptor proteins in the plasma membrane

receptor protein

protein located in the plasma membrane or within the cell; binds to a substance that alters some metabolic aspect of the cell

sodium-potassium pump

carrier protein in the plasma membrane that moves sodium ions out of and potassium ions into animal cells; important in nerve and muscle cells

solute

substance that is dissolved in a solvent, forming a solution

solution

fluid (the solvent) that contains a dissolved solid (solute)

solvent

liquid portion of a solution that serves to dissolve a solute

tight junction

junction between cells when adjacent plasma membrane proteins join to form an impermeable barrier

selectively permeable

control the flow of substances into and out of a cell

phospholipid bilayer and proteins

2 major things in membrane

heads, tails

___________ faces outword, and the _________ faces inward

carbohydrate chains

act as cell identification tags

channel proteins

tubular; allow passage of molecules through membranes

carrier proteins

combine with substances to be transported; assist passage of molecules through membrane

cell recognition proteins

provides unique chemical ID for cells; help body recognize foreign substances

receptor proteins

binds with messenger molecule; causes cell to respond to message

enzymatic proteins

carry out metabolic reactions directly

signal transduction

the binding of a messenger to a receptor may trigger this

messenger protein

attatches itself to protein to change protein which causes a chain reaction among the proteins

passive transport

no ATP requirement; molecules follow concentration gradient; high is decreasing, low is increasing; trying to reach equilibrium

lysis

swelling of the cell contents due to the gain of water

osmoregulation

control of water balance

hypotonic, hypertonic

Cells ALWAYS go from ________ to _______

receptor-mediated

specific form of pinocytosis using a coated pit

cholesterol

faulty membranes can overload the blood with

enzymes, membranes

_________ and ___________ are central to the processes that make energy available to the cell

mitochondria, cellular respiration

__________ consume oxygen in ________ _________, using the energy stored in glucose to make ATP

sunlight

nearly all the chemical energy that organisms use comes ultimately from _________

recycle

chemicals _________ among living organisms and their environment