Chapter 8: Biological Membranes

Question 1

Fatty acids are ____________ ________ that contain a ____________ chain and terminal ________ group.

Answer 1

carboxylic acids; hydrocarbon; carboyxl

Question 2

____________ fatty acids are regarded as “healthier” fats because they tend to have one or more ________ bonds and exist in ________ form at RT.

Answer 2

unsaturated; double; liquids

Question 3

Unsaturated fatty acids impart ____________ to the membrane because they cannot stack well and are liquids.

Answer 3

fluidity

Question 4

Saturated fattty acids are the main components of animal fats and tend to exist as ________ at RT.

Answer 4

solids

Question 5

By substituting one of the fatty acid chains of triacylglycerol with a phosphate group, a polar head group joins the nonpolar tails, forming a ________________.

Answer 5

glycerophospholipid (commonly known as a phospholipid)

Question 6

Phospholipids spontaneously assemble into ________ or ____________ due to hydrophobic interactions.

Answer 6

micelles, liposomes

Question 7

____________ not only regulates membrane fluidity, but it is also necessary in the synthesis of all ________, which are derived from cholesterol.

Answer 7

cholesterol, steroids

Question 8

While cholesterol stabilizes adjacent phospholipids, it also occupies space between them. Why?

Answer 8

To prevent the formation of crystal structures in the membrane and increase fluidity

Question 9

________ proteins are associated with only the interior or exterior surface of the cell membrane.

Answer 9

embedded

Question 10

Cell-cell junctions are generally comprised of ________ ____________ ____________ (CAM), which are proteins that allow cells to recognize each other and contribute to proper cell differentiation and development.

Answer 10

cell adhesion molecules

Question 11

____ ________ allow for direct cell-call communication and are often found in small bunches together. Gap junctions are also called ____________ and are formed by the alignment/interaction of pores composed of six molecules of ________.

Answer 11

gap junctions; connexons; connexin

Question 12

________ ____________ prevent solutes from leaking into the space between cells via a paracellular route. They are found where?

Answer 12

tight junctions; epithelial cells

Question 13

____________ bind adjacent cells by anchoring to their cytoskeletons.

Answer 13

desmosomes

Question 14

Desmosomes are formed by interactions between ____________ proteins associated with ____________ ____________ inside adjacent cells.

Answer 14

transmembrane; intermediate filaments

Question 15

Spontaneous processes that do not require energy (____________ delta G) proceed through ________ transport.

Answer 15

negative; passive

Question 16

Nonspontaneous processes not requiring energy (____________ delta G) proceed through ________ transport.

Answer 16

positive; active

Question 17

____________ diffusion is simple diffusion for molecules that are impermeable to the membrane. They require ________ proteins.

Answer 17

facilitated; carrier

Question 18

________ active transport uses ATP or another energy molecule to power transport. ____________ active transport, also known as, ________ transport.

Answer 18

primary; secondary, coupled

Question 19

When both particles flow the same direction across the membrane, it is termed ____________.

Answer 19

symport

Question 20

When particles flow in opposite directions, it is called ________.

Answer 20

antiport

Question 21

____________ occurs when the cell membrane invaginates and engulfs material to bring it into the cell.

Answer 21

endocytosis

Question 22

____________ is the endocytosis of fluids and dissolve particles, whereas ____________ is the ingestion of large solids like bacteria.

Answer 22

pinocytosis, phagocytosis

Question 23

Invagination is initiated and carried out by ________-________ proteins, most notably clathrin.

Answer 23

vesicle-coating

Question 24

____________ occurs when secretory vesicles fuse with the membrane, releasing material from inside the cell to the extracellular environment.

Answer 24

exocytosis

Question 25

Maintaining membrane potential requires energy because ions may passively diffuse through the cell membrane over time using ________ channels. Therefore, an ion transporter or pump such as the ________-____________ pump regulates the concentration of intracellular and extracellular Na+ and K+ ions.

Answer 25

leak; sodium-potassium

Question 26

The Na+/K+ ATPase maintains a low concentration of sodium ions and high concentration of potassium ions intracellular by pumping ____ Na+ ions for every ____ K+ ions pumped in. This removes ____ positive charge from the intracellular space of the cell to maintain the negative resting potential.

Answer 26

3, 2, 1