Levels of Organization & the Plasma Membrane Pt. 3

Question 1

What are the 4 main categories of transport processes?

Answer 1

Bulk Flow; Diffusion; Protein-Mediated Transport; and Vesicular Transport.

Question 2

Protein-Mediated Transport:

Answer 2

The majority of solutes transported across the membrane are in the form of protein mediated transport (b/c the solutes are either lipophobic or electrically charged)
- Requires a gradient (concentration, electrical, or pressure) as the driving force

Question 3

What are the 2 sub-groups of Protein-Mediated Transport?

Answer 3

Channel Transporters
and Carrier Transporters

Question 4

Channel Transporters

Answer 4

Channels with fluid filled chambers that have a direct link between the intracellular and extracellular compartments which allows very rapid transport of small ions and water across the membrane
- Can be open or gated channels

Question 5

Channel Transporters: Open Channels (Leak Channels)

Answer 5

Channels with pores open at all times that allow molecules moving in and out without restriction
- the only contributing factor for the direction of flow (high->low) is the gradient

Question 6

Second Messenger System

Answer 6

Intracellular messenger molecules (signal has to go off/be sent for the gates to be opened)

Question 7

Channel Transporters: Gated Channels

Answer 7

Is in a closed state most of the time + movement of molecules can only occur when the gate is opened.
- the opening of the gates can be regulated by: second messenger system, chemically gated channels, voltage-gated channels, and mechanically gated channels.

Question 8

Chemically Gated Channels

Answer 8

binds ligand to the extracellular receptor to open the gates (Ligand is the key and the receptor is the keyhole)

Question 9

Voltage-Gated Channels

Answer 9

changes the electrical state of the membrane

Question 10

Mechanically Gated Channels

Answer 10

Stimulation to the membrane in the form of pressure

Question 11

Carrier Transporters

Answer 11

The 2nd sub-group of protein mediated transport.
there is no direct contact of the substrate between the intracellular and extracellular compartment at any given moment
- One end of the channel is always in a closing state
- slower than channel transporters (but can move bigger molecules)

Question 12

Uniport

Answer 12

carriers that move only 1 kind of substrate

Question 13

Symport

Answer 13

carriers that move more than 1 kind of substrates in the SAME direction

Question 14

Antiport

Answer 14

Carriers that move more than 1 kind of substrates in the OPPOSITE direction

Question 15

Facilitated Diffusion

Answer 15

a process where transported molecules move down their concentration gradient (similar to simple diffusion)
- No energy is required for the transport process

Question 16

Active Transport

Answer 16

a process where transported molecules move AGAINST their concentration gradient (creates a state of disequilibrium)
- Requires ATP
- 2 types: Primary and Secondary

Question 17

Primary (Direct) Active Transport:

Answer 17

A process that requires energy in the form of ATP to create a higher concentration gradient b/w intracellular and extracellular compartments.
(these primary active transporters are also known as ATPase)

Question 18

Secondary (indirect) Active Transport

Answer 18

A process that uses the potential energy created by the primary active transport + convert them into kinetic energy for the transport of substrate against the concentration gradient

Question 19

Vesicular Transport

Answer 19

A way of transporting macromolecules that are too large for the protein-mediated transport systems (ATP is required) by the means of endocytosis and exocytosis

Question 20

Endocytosis

Answer 20

To internalize the macromolecules
3 types: Receptor-mediated Endocytosis, Phagocytosis, + Pinocytosis

Question 21

Receptor-Mediated Endocytosis (type of endocytosis)

Answer 21

Also known as clathrin-mediated endocytosis
A highly selective process that requires a receptor. receptors for specific ligand are found on the extracellular surface of the membrane.

Question 22

Phagocytosis (type of endocytosis)

Answer 22

Involves engulfing large solid particles via phagocytes (macrophages and neutrophils). The process begins when the particle binds to a plasma membrane receptor on the phagocyte.
- is non specific (engulf anything foreign)
- Eats the macromolecule using pseudopods

Question 23

Pinocytosis (type of endocytosis)

Answer 23

Process that involves enclosing the extracellular fluid non-selectively + is also known as bulk-phase endocytosis (no receptor proteins are involved)
- Pino = “gobble it up with water”

Question 24

Which transport process requires cytoplasmic vesicle to fuse with the plasma membrane, following by the secretion of vesicular contents into the extracellular fluid?

Answer 24

Exocytosis

Question 25

Exocytosis

Answer 25

Process that involves moving cytoplasmic vesicles to the plasma membrane to create secretory vesicle. involves the release of digestive enzymes, hormones, mucus, and neural transmitters

Question 26

Which of the following is NOT a true description of aquaporin?
a) channel for water
b) gated channel
c) passive movement
d) require chemical gradient

Answer 26

Gated channel

Question 27

Which vesicular transport process requires the binding of ligand to a highly selective receptor and subsequently initiates the clathrin mediated endocytosis?

Answer 27

Receptor-Mediated Endocytosis

Question 28

What process internalizes macromolecules such as dead cells, damaged cells, bacteria, viruses, etc. through the plasma membrane?

Answer 28

Phagocytosis

Question 29

Majority of the electrolytes in intracellular fluid is composed of:

Answer 29

K+

Question 30

Majority of the electrolytes in extracellular fluid is composed of:

Answer 30

Na+

Question 31

In this type of transport process, a solute binds to a specific carrier protein on one side of the membrane. This binding induces a conformational change in the carrier protein that results in the other type of solute moving down its concentration gradient to the other side of the membrane.

Answer 31

Facilitated Diffusion

Question 32

In this transport process, the energy from hydrolysis of ATP is used to drive substances across the membrane against their own concentration gradients.

Answer 32

Primary Active Transport