Topic 4.1 Cell Transportation Mechanisms

Question 1

Examples of raw materials for reactions

Answer 1

-Glucose
-ATP
-Oxygen

Question 2

Examples of toxic waste products

Answer 2

-CO2
-Water
-Lactic acid
-Urea

Question 3

Examples of things transported out of the cell

Answer 3

-Proteins
-Hormones
-Bacteria

Question 4

Properties of the cell membrane that affect transport

Answer 4

-Permeability of the membrane
-Size of the solute
-Cholesterol (changes the fluidity, thickness, compressibility and water penetration the lipid bilayer)

Question 5

How does the size of a chemical affect transport?

Answer 5

The smaller the molecule and the less strongly it associates with water, the more rapidly the molecule diffuses

Question 6

Facilitated diffusion components

Answer 6

-Larger polar molecules
-Require channel proteins
-Down the concentration gradient
-The rate of diffusion is high

Question 7

Examples of substances that require facilitated diffusion

Answer 7

-Glucose
-Carbohydrates
-Sodium ions

Question 8

Examples of substances that require simple diffusion

Answer 8

-Oxygen
-Carbon dioxide
-Lipid soluble molecules

Question 9

Examples of substances that require endo/exocytosis

Answer 9

-Hormones
-Bacteria
-Proteins

Question 10

Hypertonic solution

Answer 10

-Water only moves out of the cell
-Shrivelled cells
-High concentration of solute, low concentration of of water

Question 11

Isotonic solution

Answer 11

-Water is moving in and out of the cell
-Normal cells
-Same solute concentration inside and outside of cells

Question 12

Hypotonic solution

Answer 12

-Water only moves into the cell
-Cells swell and eventually burst
-Low concentration of solute, high concentration of water

Question 13

Water potential

Answer 13

Water potential is a measure of the potential of water to move out of a solution

Question 14

What has the highest water potential

Answer 14

Pure water; because water will always move from pure water into any solution on the other side of a partially permeable membrane

Question 15

What is the maximum water potential?

Answer 15

0kPa ; all other solution have a lower (negative) water potential

Question 16

Osmosis definition

Answer 16

Osmosis os the net movement of water molecules from an area of higher water potential to an area of lower water potential through a partially permeable membrane

Question 17

Water potential equation

Answer 17

Water potential = Turgor pressure (Ψp) + Osmotic potential (Ψs)

Question 18

What is turgor pressure?

Answer 18

Turgor pressure is the pressure generated as the swelling protoplasm pushes against the cell wall in plants

Question 19

What is the isotonic point?

Answer 19

The point where the concentration of the bathing solution is the same as the concentration of the cell

Question 20

Factors affecting the rate of active transport

Answer 20

-Oxygen concentration
-Change in pH
-Glucose concentration
-Temperature

Question 21

Pinocytosis

Answer 21

Refers to the uptake of extracellular fluids and dissolved solutes (is thought as cellular drinking)
-Links to active transport as it requires energy)

Question 22

Phagocytosis

Answer 22

The ingestion of bacteria or other materials by phagocytes.

Question 23

How to show osmosis with starch and iodine

Answer 23

-Add starch solution to a visking tube
-Place visking tube into iodine water
-Solution inside the tube turns from colourless o blush/black as the iodine water has moved into the cell

Question 24

A channel protein

Answer 24

-Acts like a pore in a membrane
-Transmembrane protein
-Involved in both entry and exit of the cell

Question 25

The two major sodium channels in mammals

Answer 25

-The voltage-gated sodium channel (VGSC)
-The epithelial sodium channel

Question 26

Voltage-gated sodium ions

Answer 26

-Opens and closes in response to changes in the membrane
-In various cell types

Question 27

Epithelial sodium channel

Answer 27

Located primarily in the skin and kidney

Question 28

Protein carriers

Answer 28

-have a binding sites for specific molecules
-Changes shape as transports molecules from one side to the other
-Proteins that carry 2 in the same direction are symporters
-If 2 moves in opposite directions they’re antiporters (requires ATP)
-GLUT 2 is found in plasma membrane in digestive system

Question 29

Simple diffusion

Answer 29

-Small molecules
-Non polar
-Doesn’t need to occur across a membrane
-Rate of diffusion is low

Question 30

Passive transport

Answer 30

The movement of particles down a concentration gradient (high to low), meaning no energy is required. Diffusion, facilitated diffusion and osmosis are all passive.

Question 31

Define facilitated diffusion

Answer 31

The movement of particles from high to low concentration through a carrier protein or channel protein.
(Used by charged substances because the cell membrane repels them).

Question 32

How might certain properties of a molecule affect how its transported?

Answer 32

-Solubility: lipid soluble molecules pass through membranes more easily
-Size: smaller molecules diffuse faster
-Charge: charged molecules cannot diffuse by simple diffusion

Question 33

How do large molecules move across a cell membrane?

Answer 33

Requires vesicles
-Endocytosis
-Exocystosis

Question 34

Active transport definition

Answer 34

The movement of molecules against a concentration gradient (low to high), meaning energy is required. Also uses carrier proteins.

Question 35

The role of ATP in active transport

Answer 35

ATP binds to the carrier protein, providing enough energy for the protein to change shape, which carries the molecule in or out of the cell.

Question 36

What is the effect of increasing the temperature on membrane permeability?

Answer 36

-Permeability of membrane increases with temperature gradually, due to increased kinetic energy of pigment molecules
-Then greater after 50°C as then the proteins in cell membrane start to denature and more pigment molecules escape.
-As temperatures increases, the fluidity increases due to movement of phospholipids/reducing bonding attraction between phospholipids