Lecture 2 Membrane Transport Mechanisms

Question 1

What transport mechanism requires energy other than kinetic energy?

Answer 1

Active transport

Question 2

What ion is most concentrated in the extracellular environmet?

Answer 2

Na+

Question 3

The sodium - potassium pump is what type of transport

Answer 3

Primary active transport

Question 4

The Sodium - Calcium pump is what type of transport?

Answer 4

Secondary Active transport

Question 5

Glucose transporters (GLUT) are what type of transporters?

Answer 5

Facilitated diffusion

Question 6

Define diffusion

Answer 6

Movement of particles from a region of high concentration to an area of low concentration

Question 7

What type of membrane is used for diffusion?

Answer 7

A membrane is not necessary for diffusion to occur but a permeable barrier can be present

Question 8

Define Osmosis

Answer 8

Movement of a solvent from a region of high concentration to an area of low concentration across a semipermeable membrane

Question 9

What is the universal solvent?

Answer 9

H2O

Question 10

Define Kinetic energy

Answer 10

energy of motion

Question 11

What creates Osmotic pressure

Answer 11

Water moves across a cell membrane because of concentration differences, water will accumulate on one side. This usually creates higher pressure one one side

Question 12

Describe the methods of molecular movement

Answer 12

It is random and has kinetic energy

Question 13

What are mechanisms for crossing cell membranes using only kinetic energy (energy independent)

Answer 13

Diffusion
Osmosis
Facilitated diffusion

Question 14

Give examples of molecules that can diffused across a cell membrane

Answer 14

Oxygen, CO2, N, alcohols

Question 15

What determines the rate of diffusion

Answer 15

Concentration differences, membrane electric potential and pressure difference

Question 16

What are the types of energy independent channels

Answer 16

Non-gated (aquaporins, ion channels)

Gated (ligand, voltage gated)

Question 17

What are aquaporins

Answer 17

Channels that are permeable to water

Question 18

What is the difference between simple diffusion and facilitated diffusion?

Answer 18

As concentration of a substance increases, in FD the rate of diffusion approaches a maximum called Vmax. as the concentration of the diffusing substance increases.

Question 19

What uses Facilitated diffusion?

Answer 19

Amino acids and glucose

Question 20

Facilitated diffusion requires what?

Answer 20

Uniporter carrier protein

Question 21

Describe uniporter

Answer 21

Has binding sites that are alternately available on either side of the membrane

Question 22

What is a major example of a uniporter

Answer 22

GLUT (glucose transporter) Allow the intake of glucose

Question 23

What is active transport?

Answer 23

Movement of particles against concentration gradient and requires energy other than kinetic (ATP)

Question 24

Define Primary Active Transport

Answer 24

Movement of particles against concentration gradient with energy derived directly from breakdown of ATP. Utilizes ATPase transporters

Question 25

Define secondary active transport

Answer 25

Energy is derived secondarily from concentration differences of molecular or ionic substances created originally by primary active transport.

Question 26

What are multiporters?

Answer 26

They are secondary active transporters that have at least one of the solutes move down its electrochemical gradient while one or more of the other solutes moves up (against) its elctrochemical gradient

Question 27

What ion is oftern involved in secondary active transport?

Answer 27

Sodium

Question 28

What are the two types of multiporters?

Answer 28

Symporters and antiporters

Question 29

Active transport always occurs when what happens?

Answer 29

When a substance moves up (against) its electrochemical gradient

Question 30

If sodium moves down its electrochemical gradient in a multiporter, why it this referred as to as secondary active transport.

Answer 30

Because we had to move the sodium out to begin with against its concentration gradient using active transport

Question 31

Sodium/ calcium antiporters move three sodium ions per calcium ion. Why does it take three sodium ions to move one calcium ion?

Answer 31

Because Calcium is much larger than sodium

Question 32

K+ channels are always open and non gated. So if a large K+ can pass through this channel then why cant a small Sodium ion pass through the channel?

Answer 32

Ions in solutions are surrounded by water molecules. A hydrated K+ ion has a larger diameter than a hydrated sodium ion. Carbonyl oxygens on the channel will pull off the water molecules. K+ is dehydrated and small enough to pass through the pore. Hydrated sodium is too small to be effected by the carbonyl oxygens