Biological Membranes Definitions

Question 1

active transport

Answer 1

The active movement of substances from a low concentration to a higher concentration (up their concentration gradient) with the use of energy in the form of ATP.

Question 2

Amphipathic

Answer 2

A molecule with both hydrophobic and hydrophilic parts.

Question 3

cell lysis

Answer 3

The bursting of an animal cell, particularly after the uptake of too much water by osmosis

Question 4

cholesterol

Answer 4

A mostly hydrophobic molecule that sits in the hydrophobic portion of the membrane and regulates membrane fluidity.

Question 5

crenation

Answer 5

The shrinking of an animal cell when placed in a hypertonic solution due to large amounts of water moving out by osmosis

Question 5

crenation

Answer 5

The shrinking of an animal cell when placed in a hypertonic solution due to large amounts of water moving out by osmosis

Question 6

endocytosis

Answer 6

The bulk uptake of substances into a cell by invagination of the membrane to
form a vesicle trapping the substances inside the cell with the use of energy in the form of ATP.

Question 7

exocytosis

Answer 7

The bulk transport of substances out of a cell using a vesicle that fuses with the
plasma membrane using energy in the form of ATP.

Question 8

facilitated diffusion

Answer 8

The net movement of substances from a high concentration to a lower concentration (down their concentration gradient) through transport proteins without the use of energy.

Question 9

fluid mosaic model

Answer 9

A model that describes membrane structure as a sea of mobile phospholipids studded with various proteins.

Question 10

hydrophilic

Answer 10

A molecule which is attracted to water.

Question 11

hydrophobic

Answer 11

a molecule which is repelled by water

Question 12

integral membrane protein

Answer 12

A type of protein bound to the membrane with strong interactions.

Question 13

osmosis

Answer 13

The net movement of water molecules across a partially permeable membrane
from a region of high water potential to a region of lower water potential without the use of ATP.

Question 14

peripheral membrane protein

Answer 14

A type of protein that is weakly bound to the surface of the membrane.

Question 15

phagocytosis

Answer 15

The ingestion of solid material (particularly pathogens and foreign material) by phagocytic cells. example of endocytosis

Question 16

phospholipid

Answer 16

A type of lipid formed by the condensation of one molecule of glycerol, two
molecules of fatty acid and a phosphate group.

Question 17

pinocytosis

Answer 17

The bulk uptake of liquids into the cell using energy in the form of ATP. example of endocytosis

Question 18

plasmolysis

Answer 18

The effect produced by placing plant cells in a hypertonic solution causing the cell to shrivel from water loss, resulting in the membrane pulling away from the rigid cell wall.

Question 19

simple diffusion

Answer 19

The spreading out of substances from a high concentration to a lower concentration (down their concentration gradient) without the use of energy

Question 20

turgid

Answer 20

A term used to describe a cell that is swollen due to large amounts of fluid uptake

Question 21

water potential

Answer 21

A measure of the tendency of water molecules to move from one area to
another measured in kilopascals (kPa) and given the symbol Ψ.