2.5 biological membranes definitions

Question 1

Active transport

Answer 1

The active movement of substances (all types of molecules through carrier proteins) from an area of low concentration to an area of higher concentration up a concentration gradient with the use of energy in the form of ATP. (active)

Question 2

Amphipathic

Answer 2

A molecule with both hydrophobic and hydrophilic parts.

Question 3

Cell lysis

Answer 3

The bursting of a cell, particularly after the uptake of too much water into an animal cell through 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 a cell when placed in a hypertonic solution due to large amounts of water moving out of the cell through 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. (active)

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 (active)

Question 8

Facilitated diffusion

Answer 8

The net movement of substances (polar molecules, charged and water soluble molecules) from a high concentration to a lower concentration down their concentration gradient through transport/channel proteins without the use of energy. (passive)

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 repels 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 energy. (passive)
or
Diffusion of water molecules from an area of low solute concentration to an area of high solute concentration through a partially permeable membrane.

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.

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.

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

Question 22

Diffusion in the phospholipid bilayer

Answer 22

passive movement of small, non-polar lipid soluble molecules such as carbon dioxide and oxygen from an area of high concentration to an area of low concentration. The molecules move directly through the phospholipid bilayer.

Question 23

why is it called the fluid mosiac model

Answer 23

The fluidity of the membrane and the mosaic
arrangement of the proteins give the structure of
the membrane its name

Question 24

The rate of gas exchange by diffusion becomes more rapid when what 3 things occur?

Answer 24

• Surface area increases
• Diffusion distance decreases
• Diffusion gradient becomes more steep

Question 25

The movement of molecules through cell membrane depends on the properties of the molecule as well as the requirements of the cell. What are the types of movement?

Answer 25

Diffusion
Facilitated Diffusion
Osmosis
Active Transport
Endocytosis
Exocytosis
Bulk Transport

Question 26

main function of the phospholipid bilayer (cell membrane)

Answer 26

controlling the movement of substances in and out of the cell/organelle. However, it also contains receptors for other molecules such as hormones and enables adjacent cells to stick together