Membrane Transport 1.4

Question 1

Diffusion

Answer 1

the movement of individual molecules of a substance through a semipermeable barrier (the membrane) from an area of higher concentration to an area of lower concentration

Question 2

Osmosis

Answer 2

osmosis is the movement of water molecules from a solution with a high concentration of water molecules to a solution with a lower concentration of water molecules, through a cell’s partially permeable membrane.

Question 3

Concentration or Osmolarity

Answer 3

amount of solute in a given volume of solvent

Question 4

Solute

Answer 4

The minor component of a solution

Question 5

Solution

Answer 5

a liquid mixture in which the minor component (solute) is uniformly distributed within the major component (the solvent)

Question 6

Solvent

Answer 6

The liquid in which a solute is dissolved to form a solution

Question 7

Concentration gradient

Answer 7

an area of high solute concentration separated from an area of low solute concentration by a membrane

Question 8

Semi-permeable membrane

Answer 8

a membrane which allows certain molecules to pass, but not others

Question 9

Passive transport:

Answer 9

Down the concentration gradient
High concentration solute -> low concentration solute
Requires no additional energy (ATP)
Diffusion, Osmosis, Facilitated diffusion

Question 10

Active Transport:

Answer 10

Up the concentration gradient
Low concentration solute -> high concentration solute
Requires energy (ATP)
Protein pumps, Endo/Exocytosis

Question 11

Simple Diffusion

Answer 11

Diffusion across a membrane
Down the concentration gradient
High concentration solute to low concentration solute.
Small Non-polar molecules
Does not require energy
Does not require membrane
proteins (like channels, pumps or carrier)

Question 12

Facilitated Diffusion

Answer 12

Diffusion
Down the concentration gradient
High concentration solute to low concentration solute.
Large or polar molecules (proteins, nucleic acids, glucose,
Uses a protein channel or transport proteins.

Question 13

Hypertonic environment (higher osmolarity)

Answer 13

Cells in a hypertonic solution will lose water and crenate (shrink)

This is as a thermodynamic result of the osmotic gradient being driven toward zero.

Question 14

Isotonic environment
(same osmolarity)

Answer 14

In an isotonic solution, the extracellular fluid has the same osmolarity as the cell.

If the osmolarity of the cell matches that of the extracellular fluid, there will be no net movement of water into or out of the cell, although water will still move in and out.

Question 15

Hypotonic environment
(lower osmolarity)

Answer 15

In a hypotonic solution, the extracellular fluid has a lower osmolarity than the fluid inside the cell; water enters the cell.

Question 16

Osmolarity

Answer 16

the concentration of a solution expressed as the total number of solute particles per liter.

Question 17

Protein Pumps

Answer 17

Against the concentration gradient.
Low conc. to high conc.
Integral proteins
Requires energy in the form of ATP to power these pumps.
Each pump is specific to a type of solute.
Eg. Sodium-Potassium ATP pump

Question 18

Endocytosis

Answer 18

Simply a process by which cells absorb external material by engulfing it with the cell membrane. (Going into the cell)

Usually subdivided into pinocytosis and phagocytosis.

Question 19

Exocytosis

Answer 19

Exocytosis is a form of active transport and bulk transport in which a cell transports molecules out of the cell. (Going out of the cell)

Question 20

Pinocytosis

Answer 20

Pinocytosis refers to the uptake of extracellular fluids and dissolved solutes, such as fat droplets, vitamins, and antigens

Question 21

Phagocytosis

Answer 21

Phagocytosis is the process by which a cell uses its plasma membrane to engulf a large particle

Question 22

Endomembrane System

Answer 22

Membranes within the eukaryotic cell that work together to modify, process and ship molecules around and out of the cell.

All made of phospholipid bilayer

Includes:
Nuclear envelope
Rough ER
Smooth ER
Transport vesicles
Golgi apparatus
Lysosomes
Secretory vesicles

Question 23

Permeability

Answer 23

the rate of passive diffusion of molecules through the membrane, which depends on the electric charge, size, and polarity of the molecule.

Question 24

Osmoregulation

Answer 24

control of the water balance of a living organism.

Question 25

Secretion

Answer 25

when material is released from a cell.

Question 26

Semi-permeable membrane

Answer 26

membrane that allows some substances to diffuse through but not others. Transport pumps proteins in the plasma membrane that use ATP to move substances across the membrane. Vesicles a bubble-like membranous structure that stores and transports cellular products.