Chapter 4 - Cell Membranes

Question 1

plasma membrane

Answer 1

The outer limit of the cytoplasm responsible for the regulation of substances moving into and out of cells.

Question 2

integral membrane proteins

Answer 2

Protein embedded in a phospholipid bilayer.

Question 3

peripheral membrane proteins

Answer 3

Protein held to membrane surfaces by noncovalent bonds formed with the polar parts of integral membrane proteins or membrane lipids.

Question 4

passive transport

Answer 4

The transport of substances across cell membranes without expenditure of energy, as in diffusion.

Question 5

simple diffusion

Answer 5

Mechanism by which certain small substances diffuse through the lipid part of a biological membrane.

Question 6

facilitated diffusion

Answer 6

Mechanism by which polar and charged molecules diffuse across membranes with the help of transport proteins.

Question 7

channel proteins

Answer 7

Transport protein that forms a hydrophilic channel in a cell membrane through which water, ions, or other molecules can pass, depending on the protein.

Question 8

gated-channel proteins

Answer 8

Ion transporter in a membrane that switches between open, closed, and intermediate states.

Question 9

carrier proteins

Answer 9

Transport protein that binds a specific single solute and transports it across the lipid bilayer.

Question 10

osmosis

Answer 10

The passive transport of water across a selectively permeable membrane in response to solute concentration gradients, a pressure gradient, or both.

Question 11

active membrane transport

Answer 11

The mechanism by which ions and molecules move against the concentration gradient across a membrane, from the side with the lower concentration to the side with the higher concentration.

Question 12

primary active transport

Answer 12

Transport in which the same protein that transports a substance also hydrolyzes ATP to power the transport directly.

Question 13

secondary active transport

Answer 13

Transport indirectly driven by ATP hydrolysis.

Question 14

symport/cotransport

Answer 14

The transport of two molecules in the same direction across a membrane. Also referred to as cotransport.
synapomorphy

Question 15

antiport

Answer 15

A secondary active transport mechanism in which a molecule moves through a membrane channel into a cell and powers the active transport of a second molecule out of the cell. Also referred to as exchange diffusion.

Question 16

membrane potential

Answer 16

The electrical potential across a cell membrane due to the unequal distribution of positively and negatively charged molecules; it is negative under resting conditions.

Question 17

electro-chemical gradient

Answer 17

A difference in chemical concentration and electric potential across a membrane.

Question 18

endocytosis

Answer 18

In eukaryotes, the process by which molecules are brought into the cell from the exterior involving a bulging in of the plasma membrane that pinches off to form an endocytic vesicle.

Question 19

phagocytosis

Answer 19

Process in which some types of cells engulf bacteria or other cellular debris to break them down.

Question 20

receptor-mediated endocytosis

Answer 20

The selective uptake of macromolecules that bind to cell surface receptors concentrated in clathrin-coated pits

Question 21

pinocytosis/bulk phase

Answer 21

Mechanism by which extracellular water is taken into a cell together with any molecules that happen to be in solution in the water.

Question 22

exocytosis

Answer 22

In eukaryotes, the process by which a secretory vesicle fuses with the plasma membrane and releases the vesicle contents to the exterior.

Question 23

phospholipid

Answer 23

A phosphate-containing lipid.

Question 24

fluid mosaic model

Answer 24

model proposing that the membrane consists of a fluid phospholipid bilayer in which proteins are embedded and float freely

Question 25

list types of transport

Answer 25

1. Active
   a) Primary Active (also hydrolyzes ATP to power transport)
   i. Pump-Mediated
   b) Secondary Active (transport indirectly driven by ATP using build up of concentration gradient)
   i. Carrier-Mediated
2. Passive
   a) Facilitated Diffusion
   i. Voltage-Gated Channel
   ii. Channel Protein
   iii. Carrier Protein
   b) Simple Diffusion