chapter 7 the cell
amphipathic
molecules containing hydrophobic and hydrophilic regions
Which of the following processes includes all of the others?
passive transport
ligand
any molecule that binds specifically to a receptor site of another molecule
phagocytosis
cell engulfs a particle in a vacuole
According to the fluid mosaic model of membrane structure, proteins of the membrane are mostly....?
embedded in a lipid bilayer
fluid mosaic model
membrane is a fluid structure with a "mosaic" of various proteins embedded in it
intercellular joining
membrane proteins of adjacent cells hook up with gap or tight junction
endocytosis
the cell takes in macromolecules by forming vesicles from the plasma membrane
ECM fibers
space between living tissue
membrane fluidity
the ability to phospholipids to move
membrane potential
-voltage difference across a membrane -voltage created by distribution of (+)(-) ions in membrane
Which of the following factors would tend to increase membrane fluidity?
a greater proportion of unsaturated phospholipids
turgid
a plant cell in a hypotonic solution swells until the wall opposes uptake ....cell is now turgid (firm)
h+
active transport
carrier proteins
bind to molecules and change shape to shuttle them across the membrane
receptor-mediated endocytosis
binding of ligands to receptors triggers vesicle formation
peripheral proteins
bound to the surface of the membrane
glycolipids
carb bound to a lipid
glycoproteins
carb bound to protein
enzymatic activity proteins
carry out steps of metabolic pathway
In what way do the membranes of a eukaryotic cell vary?
certain proteins are unique to each membrane
Based on figure 7.18, which of these experimental treatments would increase the rate of sucrose transport into a plant cell?
decreasing extracellular pH
co2
diffusion
o2
diffusion
h2o
diffusion (aquaports)
passive transport
diffusion of a substance across a biological membrane, does NOT require energy
signal transduction proteins
external messenger, shape change, relay message
glucose
facilitated diffusion, needs transport protein
cell-cell recognition proteins
glycoproteins, serve as identification tags
channel proteins
hydrophilic channel that certain molecules or ions can use as a tunnel
cholesterol
keeps membrane fluid consistent
integrins
link extracellular matrix to cytoskeleton
cytoskeleton microfilaments
made of ACTIN, function in cellular movement
phospholipid
makes up lipid bilayer, basic structure of cell membrane, has a hydrophobic tail and hydrophilic head
attachment to cytoskeleton and ECM
microfilaments or other cytoskeleton elements may be unconventionally bound to membrane proteins, helps cell shape and location of membrane proteins
pinocytosis
molecules are taken up when extracellular fluid is "gulped" into tiny vesicles
active transport
moves substances against their concentration gradient...requires energy
flaccid
no net movement of water around the cell, cell becomes limp, plant may wilt
cotransport
occurs when active transport of a solute indirectly drives transport of other substances
integral proteins
penetrate hydrophobic core
transport proteins
provide hydrophilic channels, shuttle proteins
concentration gradient
region along which the density of a chemical substance increases or decreases
hypertonic
solution concentration is greater than that inside the cell; cell loses water
hypotonic
solution concentration is less than that inside the cell; cell gains water
isotonic
solution concentration is the same as that inside the cell; no net water movement across the plasma membrane
osmosis
the diffusion of water molecules across a semi-permeable membrane
diffusion
the tendency of molecules to spread out evenly into the available space
facilitated diffusion
transport proteins speed the passive movement of molecules across the plasma membrane (no energy required)....requires a protein
exocytosis
transport vesicles migrate to the membrane, fuse with it, and release their contents outside of the cell
plasmolysis
when a cell becomes hypertonic and the membrane pulls away form the wall
