Cell membrane

Active transport can occur as a direct result of ____ ______ (ATP pump) or by coupling of the movement of one substance with that of another (symport or antiport).

ATP hydrolysis

The movement of materials through a cell membrane using energy.

Active Transport

A membrane protein, specifically a transport protein, that facilitates the passage of water through channel proteins.

Aquaporin

Proteins that bind solutes and transport them across the plasma membrane; Change shape to allow substances through

Carrier Proteins

transport proteins in the phospholipid bilayer that form "tunnels" for polar molecules to go through to get to the other side of the membrane

Channel Proteins

lipid found in the cell membrane of animals that helps keep it fluid

Cholesterol

This happens when a cell swells until pressure bursts it, resulting in cell death.

Cytolysis

movement of a substance from an area of high concentration to an area of lower concentration Diffusion

Diffusion

energy-requiring process by which large substances from the outside environment can enter a cell

Endocytosis

A condition in which a system is experiencing no net change; particles are in motion but equal in all directions

Equilibrium

A process in which substances are transported across a plasma membrane with the concentration gradient with the aid of carrier (transport) proteins; does not require the use of energy.

Facilitated Diffusion

model used to describe the fluid nature of the cell membrane Fluid Mosaic Model

Fluid Mosaic Model

said of the phospholipid head; means water loving Hydrophilic

Hydrophilic

_______ molecules tend to interact with ______ and with ____ _____.

Hydrophilic, water, each other.

said of the fatty acid tails in a phospholipid; means water fearing

Hydrophobic

________ molecules ______ interaction with water and tend to interact with other ___(FIrst Blank)__ molecules.

Hydrophobic, avoid,

Having a higher concentration of solute than another solution.

Hypertonic

Having a lower concentration of solute than another solution

Hypotonic

Having the same solute concentration as another solution.

Isotonic

the overall direction of movement for a substance

Net Movement

Diffusion of water through a selectively permeable membrane

Osmosis

_____ depends on the relative _________ of solute molecules on either side of the ______.

Osmosis, concentration, membrane

The movement of substances across a cell membrane without the use of energy by the cell

Passive Transport

Cell eating; A type of endocytosis in which a cell engulfs large particles or whole cells

Phagocytosis

plasma (cell) membrane layers composed of phospholipid molecules arranged with polar heads facing outward nonpolar tails facing inward

Phospholipid Bilayer

Cell drinking; A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes

Pinocytosis

Collapse of a walled cell's cytoplasm due to a lack of water Plasmolysis

Plasmolysis

property of the cell membrane; controls what goes in and out of the cell

Selective Permeability

In living organisms, the membrane proteins play a crucial role in directing the movement of solutes across the cell membrane. Solutes fall into one of three groups: ______ _______ (lipid soluble) molecules that cross the membrane by diffusion alone Molecules that cross the membrane due to ______-_______ transport Molecules, usually of very large size, that do not cross the membrane at all.

Small lipophilic, protein-mediated, large

A membrane transport process that carries one substance in one direction and another in the opposite direction.

antiport

When a membrane separates two _______ compartments, some molecules can move ______ across the membrane, others cannot.

aqueous, freely

Different membranes have different properties, but all share a common ________. Membranes are rich in ________, which spontaneously form _______ structures in ________.

architecture, phospholipids, bilayer, water

Membranes are ________; interior and exterior faces carry different proteins and have different properties.

asymmetric, proteins

ATP

chemical form of energy used by the cell

The resulting hypertonic animal cells are _______ and lose most or all physiological while in the shriveled state. If cells are returned to isotonic or hypotonic environments, water reenters the cell and normal functioning may be restored.

dehydrated, restored

The solute can move "_______", from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. This process is called _______ transport or facilitated diffusion, and does not require energy.

downhill, passive, facilitated

Exocytosis

energy-requiring process by which a cell expels wastes and secretes substances at the plasma membrane

As cells lose water, they lose the ability to ________ or _______.

function, divide

If concentrations of dissolved solutes are less outside the cell than inside, the concentration of water outside is correspondingly __________. When a cell is exposed to such ______ conditions, there is net water movement ______ the cell.

greater, hypotonic, into

In human tissues all cells have a _______ concentration of Na+ outside the cell than inside and a ___(First Blank)___ concentration of K+ inside the cell than outside. These concentration gradients of Na+ and K+ represent a form of _______ ________.

higher, energy storage

The surfaces of the cell membrane are __________; the interiors are _________.

hydrophilic, hydrophobic

Animal cells lack rigid cell walls. When they are exposed to _________ environments, water rushes out of the cell, and the cell shrinks.

hypertonic

Plant cells are surrounded by rigid cell walls. When plants cells are exposed to _______ environments, water rushes out of the cell and the cell shrinks away from the rigid wall, resulting in ________. The plasmolyzed cells are dehydrated and lose most or all physiological functions while in the shriveled state.

hypertonic, plasmolysis

When cells are in ________ solution, movement of water out of the cell is exactly balanced by movement of water into the cell. A _____% solution of NaCl (_______) is isotonic to ______ cells.

isotonic, .9, saline, animal

If cells are returned to _______ or _______ environments, water reenters the cell and normal functioning may be restored.

isotonic, hypotonic

A few _______ substances move across the cell membrane by passive diffusion. Most small molecules or ions require the assistance of specific _______ _______ to transport them across the membrane. ______ molecules do not cross intact cell membranes, except in certain special cases.

lipophilic, protein carriers, Large

If concentrations of dissolved solutes are greater outside the cell, the concentration of water outside is correspondingly ________. As a result, water inside the cell will flow _______ to attain equilibrium, causing the cell to ______.

lower, outwards, shrink

burst meaning for cells

lyse

Hypertonic comes from the Greek "hyper", meaning ________ and "tonos" meaning _______. In a hypertonic solution the total molar concentration of all dissolved solute particles is _________ than that of another solution, or greater than the concentration in a cell.

over, stretching, greater

Membranes consist of a ___________ ________ combined with a variety of proteins in a ______ ______ arrangement.

phospholipid bilayer, fluid mosaic

The _______ or _______ of cell walls influences how cells respond to osmotic fluctuations in their environment.

presence, absence, osmotic

Most biologically important solutes require _____ _______ to cross cell membranes, by a process of either passive or active transport.

protein carriers

Water moves readily across cell membranes through special _____________, and if the total concentration of all dissolved solutes is not equal on both sides, there will be net movement of water molecules into or out of the cell and which direction it moves depends on whether the cell's environment is isotonic, hypotonic, or hypertonic

protein-lined channels

Membrane _______ and _______ can diffuse ______ within the membrane, giving it the properties of a _____ ______.

proteins, lipids, laterally, fluid mosaic

Cell membranes are ______ _________. Some solutes cross the membranes freely, some cross with assistance, and others do not cross at all.

selectively permeable

Cells without walls will _______ and may ______ if excess water is not removed from the cell.

swell, burst

A membrane transport process that carries two substances in the same direction across the membrane.

symport

Animal cells lack rigid cell walls. When they are exposed to hypotonic environments, water rushes into the cell and the cell swells. Eventually, if water is not removed from the cell, the pressure will exceed the ______ ________ of the cell, and it will burst open, or lyse. Many single-celled protests living in freshwater environments have _________ _______ that _____water back out of the cell in order to maintain osmotic equilibrium and avoid lysis.

tensile strength, protests, contractile vacuoles, pump, equilibrium

Biological membranes are _____, ______ surfaces separating cells and cell compartments from their environments.

thin, flexible

Hypotonic comes from the Greek "hypo," meaning ______ and "tonos" meaning _______. In a hypotonic solution the total molar concentration of all dissolved solute particles is _______ than that of another solution or less than that of a cell.

under, stretching, less

Active transport uses energy to move the solute "______" against the ______, whereas in facilitated diffusion, a solute moves down its concentration gradient and no energy is required.

uphill, gradient, energy

Cells with ______ often ________ from the _______ _______ that develops in _______ environments.

walls, benefit, turgor pressure, hypotonic