Lecture 11

Question 1

What are the conditions that need to be met for cells to survive?

Answer 1

• Exchange between neighbouring cells
• Exchange within the cell itself (intracellular environment)
• Exchange between the surrounding intercellular medium (extracellular matrix)

Question 2

What affects rates of facilitated diffusion?

Answer 2

• The concentration gradient

Question 3

What are active transport systems usually inhibited by?

Answer 3

Low temperatures

Question 4

What energy does the secondary active transport use?

Answer 4

The electrochemical gradient

Question 5

Why do some cells produce and accumulate secretory vesicles?

Answer 5

To be able to release large amounts of active molecules on demand

Question 6

What are two general mechanisms involved in membrane transport?

Answer 6

Macrotransfer and microtransfer

Question 7

Macrotransfer?

Answer 7

• Transport of macromolecules

- Only brings materials into endosomes or lysosomes within the cytoplasm

Question 8

Microtransfer?

Answer 8

• Transfer of small molecules and ions across the cell membrane, both external and internal

Question 9

What must happen for molecules to be absorbed into the cytoplasm?

Answer 9

They must cross the surrounding membrane

Question 10

What are two different mechanisms for the microtransfer of biomolecules?

Answer 10

• Passive transport (simple diffusion)

- Active transport (requires energy)

Question 11

Brownian movement?

Answer 11

The first time someone indirectly observed the passive transport of biomolecules

Question 12

What is passive transport?

Answer 12

The simple diffusion of substances

Question 13

What is diffusion dependent on?

Answer 13

It is dependent on the movement of molecules due to their kinetic energy (high concentration to low concentration)

Question 14

When does movement in a cell stop?

Answer 14

When the concentration equilibrium gradient constant reaches 0

Question 15

Facilitated transport?

Answer 15

• A passive transport system, since it uses no energy

- Uses a set of carrier proteins, which are highly selective

Question 16

Active transport?

Answer 16

• Some macromolecules don’t pass freely through the cell membranes, so these molecules require the use of pores or channels (membrane transport proteins)
• Requires energy (ATP)

Question 17

Primary active transport?

Answer 17

Moves molecules against their electrochemical gradient by using ATP

Question 18

Secondary active transport?

Answer 18

Moves molecules together through symport (in the same direction), or antiport (in opposite directions)