chapter 5 online
these are forms of bulk transport
Endocytosis, Pinocytosis, Receptor-mediated endocytosis, and Phagocytosis
use contractile vacuoles to actively pump water out of the cells
Paramecium
when phospholipids are placed in water, they spontaneously form
a bilayer
a defining feature of biological membranes is the presence of
a lipid bilayer
triglycerides and phospholipids are different because only phospholipids have
a polar "head" and 2 nonpolar "tails"
mechanism used by red blood cells to keep the concentration of glucose inside the cell high?
after glucose enters the cell, it is phosphorylated so it can no longer bind to the glucose transporter and leave the cell
this cell would burst if placed in a hypotonic solution
animal cell
water flow across the plasma membrane is facilitated by special channel proteins called
aquaporins
phospholipids contain
backbone dervived from glycerol, a polar "head" and 2 nonpolar "tails", and one phosphate group
are moved by facilitated diffusion
bicarbonate ions, chloride ions, and glucose
substances that move across the plasma membrane by facilitated diffusion are
bicarbonate ions, chloride ions, and glucose
during receptor-mediated endocytosis, what triggers the formation of an endoctic vesicle?
binding of the target molecules to their matching receptors
substances enter or leave the cell packaged inside membranes vacuoles or vesicles that either fuse with or pinch off from the plasma membrane during a process called
bulk transport
how can large polar molecules enter the cell
bulk transport, coupled transport, and facilitated diffusion
low density lipoprotein brings _____ into the cell where it can be incorporated into cell membranes
cholesterol
concentration of a substance varies from 1 region to another
concentration gradient
mechanisms of active transport
coupled transport and sodium-potassium pump
transport protein that uses energy from ATP indirectly
coupled transport proteins
cell membranes
degree of membrane fluidity varies depending on the composition of the membrane, individual lipids and unanchored proteins are relatively free to move around laterally within the lipid bilayer
net movement of a substance from a region where it has higher concentration to a region where it has lower concentration is called
diffusion
these involve passive transport
diffusion and facilitated diffusion
during receptor-mediated endocytosis these occur
each receptor is specific for a particular type of target molecule, formation of a vesicle is triggered when the properly shaped target molecule binds with its matching receptor, and molecules being transported bind to receptors embedded in the plasma membrane
during ______, the plasma membrane surrounds and envelopes smaller cells, solid particles, or liquids
endocytosis
the 2 main categories of bulk transport are_____ and _____
endocytosis and exocytosis
how can cells allow large polar molecules to enter the cell?
enter by endocytosis, enter though channel proteins, enter though carrier proteins
cells that have internal membrane along with plasma membrane
eukaryotic cells only
fusion of s secretory vesicle with a plasma membrane in order to discharge the contents of the vesicle
exocytosis
which region of a phospholipid molecule is hydrophobic?
fatty acid hydrocarbon chains
surround cells with an isotonic extracellular fluid
humans
water is attracted to charged or polar solutes, forming ______ _____ around them
hydration shells
transmembrane domains are composed of ______ amino acids and are typically arranged into _____ helics
hydrophobic , alpha
4 main components of plasma membrane
interior protein network, lipid bilayer, transmembrane proteins, and cell surface markers
plasma membrane
is a fluid and is selectively permeable
when 2 solutions have the same concentration of solutes
isotonic
typical components of biological membranes
lipids and proteins
individual lipids and unanchored proteins are relatively free to move around laterally within the membrane
membrane fluidity
placement of integral membrane proteins are
nonpolar regions are inserted into the membrane and the polar regions protrude from its surface
surround the cells with a rigid cell wall that can withstand the pressure that builds up inside the cells due to the inflow of water by osmosis
oak tree
why is active transport so important?
only active transport can move a substance from an area where it has lower concentration to an area where it has a higher concentration
how do channel and carrier proteins differ?
only carrier proteins can be used for active transport, only carrier proteins actually bind to the substance being transported
faciliated diffusion by carrier proteins differs from simple diffusion due to
only facilitated diffusion by carrier proteins exhibits saturation
facilitated diffusion by carrier proteins differs from simple diffusion due to
only facilitated diffusion by carrier proteins exhibits saturation
how do phagocytosis and pinocytosis differ?
only pinocytosis involves intake of liquids
eukaryotic cells have internal membranes that surround their
organelles
methods of passive transport are
osmosis, transport of water by aquqporins
the combined concentration of all solutes in a solution determines the _______ ______ of the solution
osmotic concentration
Does not require an expenditure of energy by the cell itself
passive transport
mechanisms of endocytosis
phagocytosis, pinocytosis, and receptor-mediated endocytosis
lipid bilayer that forms the core of all cell membranes is composed primarily of
phospholipids
structure that surrounds all cells
plasma membrane
describes facilitated diffusion
requires assistance of proteins and requires a concentration gradient
at high solute concentrations, further increases in the solute concentration no longer increase the rate of diffusion. this means that carrier proteins exhibit _____
saturation
coupled transport of glucose molecules across the cell membrane uses energy released from the concentration gradient of
sodium
how does sodium potassium work?
sodium is transported out the cell, energy from ATP is used to actively transport sodium up its own concentration gradient, phosphorylation of the carrier protein causes it to change shape and release sodium ions outside the cell
substances that cant easily cross the lipid bilayer can still diffuse across the plasma membrane with the help of?
specific channel proteins or carrier proteins
carrier proteins that transport 2 different types of molecules may be either _____ or ______
symporters or antiporters
in cell membranes, what is the main barrier to the free passage of water-soluble ions and molecules?
the interior of the lipid bilayer
in phospholipids, a polar charged organic molecule is ofter attached to
the phosphate group
phospholipids form bilayers when mixed with water due to which of the following?
their polar heads are attracted to water, their nonpolar tails repel water
a ______ electron microscope is required to view the double layers of a membrane
transmission
describes the sodium-potassium pump
uses energy from ATP to alter the conformation of the carrier protein, it moves sodium ions and potassium ions across the membrane in opposite directions, and it is an active transport mechanism
