Lecture 2 Membrane Transport Mechanisms Flashcards Preview

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Flashcards in Lecture 2 Membrane Transport Mechanisms Deck (32):
1

What transport mechanism requires energy other than kinetic energy?

Active transport

2

What ion is most concentrated in the extracellular environmet?

Na+

3

The sodium - potassium pump is what type of transport

Primary active transport

4

The Sodium - Calcium pump is what type of transport?

Secondary Active transport

5

Glucose transporters (GLUT) are what type of transporters?

Facilitated diffusion

6

Define diffusion

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

7

What type of membrane is used for diffusion?

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

8

Define Osmosis

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

9

What is the universal solvent?

H2O

10

Define Kinetic energy

energy of motion

11

What creates Osmotic pressure

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

12

Describe the methods of molecular movement

It is random and has kinetic energy

13

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

Diffusion
Osmosis
Facilitated diffusion

14

Give examples of molecules that can diffused across a cell membrane

Oxygen, CO2, N, alcohols

15

What determines the rate of diffusion

Concentration differences, membrane electric potential and pressure difference

16

What are the types of energy independent channels

Non-gated (aquaporins, ion channels)
Gated (ligand, voltage gated)

17

What are aquaporins

Channels that are permeable to water

18

What is the difference between simple diffusion and facilitated diffusion?

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.

19

What uses Facilitated diffusion?

Amino acids and glucose

20

Facilitated diffusion requires what?

Uniporter carrier protein

21

Describe uniporter

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

22

What is a major example of a uniporter

GLUT (glucose transporter) Allow the intake of glucose

23

What is active transport?

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

24

Define Primary Active Transport

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

25

Define secondary active transport

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

26

What are multiporters?

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

27

What ion is oftern involved in secondary active transport?

Sodium

28

What are the two types of multiporters?

Symporters and antiporters

29

Active transport always occurs when what happens?

When a substance moves up (against) its electrochemical gradient

30

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

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

31

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

Because Calcium is much larger than sodium

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?

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