Anatomy Lecture Ch 3 Flashcards
The Cellular Level of Organization
plasma membrane
cell’s flexible outer surface, separating the cell’s internal environment from the external environment
selective barrier that regulates the flow of materials into and out of a cell
communication between cells and external environment
cytoplasm
consists of all the cellular contents between the plasma membrane and the nucleus; cytosol and organelles contained within
cytosol
the fluid portion of cytoplasm; contains water, dissolved solutes, and suspended particles
nucleus
a large organelle that houses most of a cell’s DNA
chromosome
a single molecule of DNA
genes
hereditary units that control most aspects of cellular structure and function
fluid mosaic model
the molecular arrangement of the plasma membrane resembles a continually moving sea of fluid lipids that contains a mosaic of many different proteins
lipid bilayer
two back-to-back layers made up of three types of lipid molecules: phospholipids, cholesterol, and glycolipids
phosphoplipid
about 75% of the membrane lipids
contain phosphorus
cholesterol
a steroid with an attached OH group
glycolipids
lipids with attached carbohydrate groups
amphipathic
lipids have both polar and nonpolar parts
integral proteins
extend into or through the lipid bilayer and are firmly embedded in it
transmembrane proteins
span the entire lipid bilayer and protrude into both the cytosol and extracellular fluid
peripheral proteins
not as firmly embedded in the membrane
attached to the polar heads of membrane lipids or to integral proteins at the inner or outer surface of the membrane
glycoproteins
proteins with carbohydrate groups attached to the ends that protrude into the extracellular fluid
glycocalyx
an extensive sugary coat formed by the carbohydrate portions of glycolipids and glycoproteins
ion channels
pores or holes formed by integral proteins that specific ions can flow through to get into or out of the cell
most ion channels only allow a single type of ion to pass through
carriers
some integral proteins act as carriers and selectively move a polar substance or ion from one side of the membrane to the other
receptors
cellular recognition sites
each type of receptor recognizes and binds a specific type of molecule
ligand
a specific molecule that binds to a receptor
enzymes
catalyze specific chemical reactions
linkers
anchor proteins in the plasma membranes of neighboring cells to one another or to protein filaments inside and outside the cell
cell-identity markers
enable a cell to recognize other cells of the same kind during tissue formation or recognize and respond to potentially dangerous foreign cells
blood types are a form of cell-identity markers
concentration gradient
a difference in the concentration of a chemical from one place to another, such as from the inside to the outside of the plasma membrane
electrical gradient
a different in electrical charges between two regions
electrochemical gradient
combined influence of the concentration gradient and the electrical gradient on movement of a particular ion
passive transport processes
a substance moves down its concentration gradient
moves from higher to lower concentration
uses only the cell’s kinetic energy
active transport processes
cellular energy is used to drive the substance against its concentration or electrical gradient
moves from lower to higher concentration
requires ATP
vesicles
tiny, spherical membrane sacs used into transport
diffusion
a passive process in which the random mixing of particles in a solution occurs because of the particles’ kinetic energy
simple diffusion
a passive process in which substances move freely through the lipid bilayer of the plasma membranes of cells without the help of membrane transport proteins
facilitated diffusion
used with solutes that are too polar or highly charged
an integral membrane protein assists a specific substance across the membrane
the integral membrane proteins can either form a channel or act as a carrier
channel-mediated facilitated diffusion
a solute moves down its concentration gradient across the lipid bilayer through a membrane channel
carrier-mediated facilitated diffusion
a carrier moves a solute down its concentration gradient across the plasma membrane
this is a passive process so no cellular energy is required
osmosis
a type of diffusion in which there is net movement of a solvent through a selectively permeable membrane
passive process
aquaporins (AQPs)
integral membrane proteins that function as water channels
play a critical role in controlling the water content of cells
osmotic pressure
proportionate to the concentration of the solute particles that cannot cross the membrane
the higher the solute concentration, the higher the solution’s osmotic pressure
tonicity
a measure of the solution’s ability to change the volume of cells by altering their water content
isotonic solution
any solution in which a cell maintains it normal shape and volume
hypotonic solution
a solution that has a lower concentration of solutes than the cytosol inside the RBCs
hemolysis
rupture of RBCs
lysis
the rupture of other type of cells due to placement in a hypotonic solution
hypertonic solution
higher concentration of solutes than does the cytosol inside RBCs
crenation
shrinkage of cells when placed in a hypertonic solution
active transport
energy is required for carrier proteins to move solutions across the membrane against a concentration gradient
primary active transport
energy derived from hydrolysis of ATP changes the shape of a carrier proteins which pumps a substance across a plasma membrane against its concentration gradient
secondary active transport
the energy stored in a Na+ or H+ concentration gradient is used to drive other substances across the membrane against their own concentration gradients
pumps
carrier proteins that mediate primary active transport
symporters
transporters that move two substances in the same direction