MB Chapter 5

exocytosis

A membranous vesicle is fusing with the plasma membrane and releasing its contents into the extracellular fluid.

facilitated diffusion. In facilitated diffusion, molecules use a transport protein to move across the plasma membrane. There is a net movement of molecules down the concentration gradient -- that is, there is a net movement of molecules from where they are more concentrated to where they are less concentrated.

A molecule moves down its concentration gradient using a transport protein in the plasma membrane. This is an example of

hypertonic

A plant cell placed in a(n) ___________ solution will lose water and plasmolyze.

isotonic

A plant cell surrounded by a(n) __________ solution will be flaccid (limp).

phagocytosis Phagocytosis occurs when a cell engulfs a large particle.

A white blood cell engulfing a bacterium is an example of _____.

hypotonic

An animal cell placed in a(n) _________ solution will gain water, swell, and possibly burst.

passive transport.

Diffusion does not require the cell to expend ATP. Therefore, diffusion is considered a type of

into ... membranous vesicles The prefix "endo-" means "inward."

Endocytosis moves materials _____ a cell via _____.

cholesterol molecules At low temperatures, cholesterol hinders solidification of the membrane because it prevents the close packing of phospholipids.

Fluidity of an animal cell plasma membrane is enhanced by __________.

glycoprotein Structure A is composed of both a carbohydrate and a protein.

Identify Structure A.

phospholipid bilayer of membrane Phospholipids can be recognized by the presence of a head and two tails.

Identify Structure D.

molecules move across the plasma membrane against their concentration gradient. Molecules move against their concentration gradient in active transport.

In active transport,

the diffusion of water.

Osmosis can be defined as

drinking.

Phagocytosis is to eating as pinocytosis is to

the plasma membrane allows some substances to enter or leave a cell more easily than others.

Plasma membranes are selectively permeable. This means that

is hypotonic to the protozoan.

Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles tells you that the environment

helps to keep phospholipids from being too close to one another.

The cholesterol associated with animal cell membranes

a hypertonic sucrose solution Water moves by osmosis from the hypotonic environment, the cell interior, to the hypertonic environment.

The concentration of solutes in a red blood cell is about 2%. Sucrose cannot pass through the membrane, but water and urea can. Osmosis would cause red blood cells to shrink the most when immersed in which of the following solutions?

hypotonic

The ideal osmotic environment for a plant cell is a(n) ___________ environment.

isotonic

The ideal osmotic environment for an animal cell is a(n) ____________ environment.

so that the non polar parts of two lipids point toward each other A phospholipid bilayer can exist as a stable boundary between two aqueous compartments because the molecular arrangement shelters the hydrophobic tails of the phospholipids from water while exposing the hydrophilic heads to water.

The lipids in a cell membrane are arranged _____.

endocytosis. In endocytosis, the plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell.

The plasma membrane forms a pocket that pinches inward, forming a vesicle that contains material from outside the cell. This describes the process of

phagocytosis.

The process of a white blood cell engulfing a bacterium is

active transport. The sodium-potassium pump moves ions across the plasma membrane against their concentration gradients. This requires energy and is an example of active transport.

The sodium-potassium pump uses energy from ATP to move sodium ions out of the cell, and potassium ions into the cell. This is an example of

hypertonic

There is a net diffusion of water out of an animal cell when it is placed in a(n) ___________ solution.

facilitated diffusion Diffusion is occurring via a transport protein.

This process is referred to as _____.

through facilitated diffusion or diffusion. Water can cross the plasma membrane through the process of facilitated diffusion. However, water molecules can also cross the lipid bilayer directly.

Water crosses the plasma membrane

stabilization of the phospholipids Cholesterol helps to stabilize the structure of the plasma membrane.

What is the function of Structure E?

remain standing upright The water balance in plants is remarkably different. In an isotonic solution plant cells will look flaccid (limp), and in a hypotonic environment they will be turgid (firm). The cell wall allows the plant cell to balance the osmotic pressures inside the cell.

When placed in a hypotonic environment, where the solute concentration is below that of the cell, a houseplant will _____.

Active transport requires the expenditure of cellular energy, and facilitated diffusion does not. Active transport can move substances against the concentration gradient, but it requires energy, usually in the form of ATP.

Which of the following is a difference between active transport and facilitated diffusion? - Facilitated diffusion involves transport proteins, and active transport does not. - Facilitated diffusion can move solutes against a concentration gradient, and active transport cannot. - Active transport requires the expenditure of cellular energy, and facilitated diffusion does not. - Active transport involves transport proteins, and facilitated diffusion does not.

Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated.

Which of the following statements regarding diffusion is false? -Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated. - Diffusion requires no input of energy into the system. -Diffusion occurs even after equilibrium is reached and no net change is apparent. -Diffusion is a result of the thermal energy of atoms and molecules.

Lipid soluble molecules are hydrophobic.

Which of these is hydrophobic like the interior of the plasma membrane? lipid soluble molecule water glucose hydrogen ion

pinocytosis ... the cell is engulfing extracellular fluid Pinocytosis is "cell drinking."

You know that this process is _____ because _____.

A receptor protein is involved in this process.

receptor-mediated endocytosis

phagocytosis

the engulfing of large particles.

The protein is allowing solute molecules to enter the cell.

transport protein