1.3- 1.4 Membrane Structure and Transport

Question 1

Amphipathic

Answer 1

A molecule that has both a hydrophilic region and a hydrophobic region, such as a phospholipid.

Question 2

Phospholipid

Answer 2

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic phosphate head and a nonpolar, hydrophobic lipid tail.

Question 3

Phospholipid bilayer

Answer 3

A double layer of phospholipids that makes up plasma and organelle membranes. It has proteins embedded in it, and it is semipermeable.

Question 4

Cholesterol

Answer 4

A steroid that is an important component of animal cell membranes and that acts to reduce fluidity and permeability of the membrane.

Question 5

Fluid-mosaic Model

Answer 5

Model for the plasma membrane based on the changing location and pattern of protein molecules in a fluid phospholipid bilayer.

Question 6

Davson-Danielli Model

Answer 6

Model of membrane structure developed after the invention of electron microscopes in the 1930s, which envisioned a sandwich model where a phospholipid bilayer was between two layers of proteins.

Question 7

Glycoprotein

Answer 7

Carbohydrate chains attached to a peripheral protein on the outer surface of plasma membrane. Acts as a recognition site for hormones and neurotransmitters. Also allows cells to attach to one another to form tissues and recognize other cells.

Question 8

Peripheral protein

Answer 8

Protein appendages loosely bound to the surface of the membrane and not embedded in the lipid bilayer.

Question 9

Integral protein

Answer 9

Integrated into the Phospholipid bilayer, they form membrane channels that regulate the passage of specific ions through the membrane.

Question 10

Facilitated diffusion

Answer 10

Movement of a substance from high to low concentration with the help of a protein channel.

Question 11

Diffusion

Answer 11

Movement of molecules from an area of higher concentration to an area of lower concentration.

Question 12

Active transport

Answer 12

The movement of a substance across a biological membrane against its concentration gradient with the help of energy input and specific protein pumps.

Question 13

Osmosis

Answer 13

Diffusion of water molecules through a semipermeable membrane from a place of lower solute concentration to a place of higher solute concentration.

Question 14

Isotonic

Answer 14

When the concentration of two adjacent solutions is the same.

Question 15

Hypertonic

Answer 15

A solution that has a higher solute concentration than the adjacent solution.

Question 16

Exocytosis

Answer 16

A process in which a vesicle inside a cell fuses with the membrane and releases its contents to the external environment. Transports to outside of cell or organelle.

Question 17

Endocytosis

Answer 17

Cellular uptake of biological molecules and particulate matter via formation of new vesicles from the plasma membrane.

Question 18

Pinocytosis

Answer 18

A type of endocytosis in which the cell ingests extracellular fluid and its dissolved solutes.

Question 19

Phagocytosis

Answer 19

A form of endocytosis that involves the formation of a membrane vesicle, which engulfs a particle such as bacterium.

Question 20

Sodium-potassium pump

Answer 20

A carrier protein that uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell.

Question 21

Hydrophilic

Answer 21

Attracted to water (ie polar or charged).

Question 22

Hydrophobic

Answer 22

Repelled by water (ie non-polar or uncharged).

Question 23

Polar

Answer 23

Charged, and therefore hydrophilic.

Question 24

Non-polar

Answer 24

Uncharged, and therefore repelled by water.