Mastering Bio - Membrane structure and function

diffusion statement

A PASSIVE PROCESS

How does cholesterol affect membrane fluidity?

At body temperature, it makes the membrane less fluid.

integral protein statement

exhibit both hydrophilic and hydrophobic properties

Cells A and B are the same size, shape, and temperature, but cell A is metabolically less active than cell B; cell B is actively converting oxygen to water in cellular respiration. Oxygen will diffuse more rapidly into cell __________ because __________.

B ; diffusion gradient in cell B is steeper

In facilitated diffusion, __________ proteins provide openings in the plasma membrane for substances to flow through without changing structure, and __________ proteins allow passage of substances through the plasma membrane after undergoing a subtle change in shape.

channel ; carrier

All cells have voltages across their membranes. This voltage is called a(n) __________ and is often maintained by __________.

membrane potential ; electrogenic pumps

How does the "fluid mosaic model" describe the structure of the plasma membrane?

mosaic - proteins in membrane fluidity - lateral and rotational movement of phospholipids

A cell is placed into a solution and the cell shrinks. Which of the following is true regarding the solution?

solution is HYPERtonic

The plasma membrane exhibits selective permeability. This means that __________.

the plasma membrane allows some substances to flow through it more easily than others

peripheral protein statement

these proteins are found only on surface of plasma membrane

sodium-potassium pump

transports sodium ions out of the cell and transports potassium ions into the cell

Which of the following molecules is most likely to passively diffuse across the plasma membrane?

CO2, hydrocarbons, oxygen - nonpolar, hydrophobic molecules that dissolve in lipid bilayer

Which of the following would be least likely to diffuse through a plasma membrane without the help of a transport protein?

a large polar molecule

Which of the following substances would be most likely to pass through the plasma membrane without the help of a transport protein?

a nonpolar molecule, such as a hydrocarbon

Red blood cells contain approximately a 2% concentration of solutes. A red blood cell is placed into a solution that contains a 4% concentration of solutes to which the cell is not permeable. What will happen to the red blood cell?

cell size will decrease as water flows out of it less water/more solute outside

The internal solute concentration of a plant cell is about 0.8M. To demonstrate plasmolysis, it would be necessary to suspend the cell in what solution?

solution with greater molarity than what is inside cell

What is the concrete difference between active transport and facilitated diffusion?

Active transport - requires energy from ATP facilitated diffusion does not

Why is energy required for active transport?

Because it moves solutes against their concentration gradient

If a red blood cell and a plant cell were placed in seawater, what would happen to the two types of cells?

both cells would lose water red blood cell - shrivels plant plasma membrane - pulls away from cell wall

Which of the following plant cells would exhibit the most turgor pressure?

cell in hypotonic solution

what function do carbs fulfill in plasma membrane?

cell-to-cell recognition

A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via which process?

endocytosis

What accounts for replacement of lipids and proteins lost from plasma membrane?

exocytosis and smooth and rough ER

Facilitated diffusion statement

facilitated diffusion of solutes may occur through channel or transport proteins in the membrane

carbs associated with plasma membrane statement

membrane cards function primarily in cell-cell regulation

passive transport statement

permits the solute to move in either direction, but net movement of solute occurs down the concentration gradient of the molecule

Which of the following molecules are most abundant in the plasma membrane?

phospholipids

Which of the following statements about the role of phospholipids in the structure and function of biological membranes is correct?

phospholipids form selectively permeable membrane

Which of the following cell structures exhibits selective permeability between a cell and its external environment?

plasma membrane

Which molecules require transport protein to pass membrane?

polar and large - glucose, ions

Which of the following structural arrangements of the components in biological membranes facilitates the cell membrane's property of selective permeability?

proteins embedded in two laters of phospholipids