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Flashcards in Transporters and channels Deck (51):
1

What two types of transport might involve coupling of solute movements?

Facilitative and active transport

2

Name the 3 types of biological solutes that does not pass through the membrane ?

Inorganic ions Sugars Amino acids

3

Name the 4 ways to increase solute movement across a membrane or cell layer?

1) Increase area 2) Decrease the thickness 3) Increase the conc gradient between the outside and inside 4) Increase the permeability

4

What is the equation of solute flux?

J1->2 = DA (delta c)/x

5

What are the two types can pores be?

1) water-filled channels 2) Facilitative transporters

6

Name the 4 important characteristics of pores?

1) solute flux (passive diffusion) 2) Substrate specific 3) Saturable 4) Specific inactivators

7

Define transportome?

1289 genes are transporters and channels. ie 4% of human genome

8

How are the transportome classified?

Into structurally related super-families and families

9

Name the 3 types of transportome?

1) ATP-powered pump 2) Ion channel 3) Transporter

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10

What are the two terms to describe transporters?

Carriers and permeases

11

What transportome is the fastest are transport ions across the membrane?

Ion channel

12

What transportome is the most precise at transporting ions across the membrane?

Transporter

13

What transportome is used for the ions to cross the membrane against its concentration gradient?

ATP pump

14

What are the characteristics of the voltage-gated potassium channel?

- large and fast solute flux (when open) - Selectivity related to size and charge of hydrated ion.

15

What is the hydrated ion diameter of a potassium ion?

6A

16

What is the hydrated ion diameter of a sodium ion?

8A

17

What is the hydrated ion diameter of a calcium ion?

12A

18

What is the relationship between charge density and diameter of the solute?

The smaller the solute the higher the charge density is

19

Name the 3 types of basic transporter mechanisms?

1) Uniport 2) Symport 3) Antiport

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20

What two types of basic transport mechanisms are coupled to solute movements?

Symport and antiport

21

What are the key difference between transporters and pores?

Transport are relatively slow between a pore. Transporters are more precise in the solutes they transport while a pore is not.

22

What does the term "cis face" mean?

the proximal (closest) face of the golgi apparatus

23

What does the term "trans face" mean?

the distal (further away) face of the golgi apparatus

24

What type of mechanism is reversible when looking at solute flux?

Transport mechanisms such as facilitative transport

25

What type of transporter changes conformation quicker?

substrate-loaded transporter

26

What is basic transport mechanisms is quicker at transferring solutes?

Antiport is quicker than uniport.

27

Define the anti port?

A mechanism of coupling the transport of two compounds across a membrane in opposite directions?

28

Name the two types of anti ports?

Homoexchange (the same solutes is passed in both directions) Heteroexchange (two different solutes are linked)

29

Define uniport?

Transport of a molecule or ion through a membrane by a carrier mechanisms without known coupling to the transport of any other molecule or ion

30

Define symport?

Mechanism of transporting two compounds simultaneously across a cell membrane in the same direction. One being transported down its conc gradient and the other against

31

Name the 2 kinetic characteristics of transporters?

1) Cis-effect 2) Trans-effect

32

Name the 2 properties of the cis-effect when looking at kinetic characteristics of transporters?

1) Saturability 2) Sterospecificity

33

Define "saturability"?

Substrate molecules compete for transporter binding sites. Therefore there is a limited number of solutes that can be transported at a time

34

Define "sterospecificity"?

Certain stereoisomers are better "fit" to binding site. Solutes all vary is shape and size- therefore a lot of them fit into binding sites however some bind more readily than others and therefore can activate them more readily.

35

Name the 2 properties of the trans-effect when looking at kinetic characteristics of transporters?

1) Exchange diffusion 2) Counter transport

36

Define "exchange diffusion"?

Trans-substrate accelerates exchange

37

Define "Counter transport"?

Trans-acceleration by a different substrate (hetero-exchange)

38

What are the three characteristics of a channel?

1) Selectivity related to size and charge of hydrated ion. 2) Conformational change (gated??) 3) Diffusion single-file through narrow point of channel (saturable)

39

What are the 5 characteristics of a transporter?

1) Selectivity related to molecular interaction between solute and binding site. 2) Conformational change predicted 3) Carriage requires absorption 4) Requirement of co-substrates in many cases 5) Exhibit counter-transport

40

What is the michaelis-menten equation?

v= Vmax. [S]/ Km + [S]

41

What does the v stand for in the michaelis-menten equation?

Velocity of reaction

42

What does the [S] stand for in the michaelis-menten equation?

Substrate concentration on cis face of membrane

43

What does the Vmax stand for in the michaelis-menten equation?

Maximum velocity where all binding-sites are occupied

44

What does the Km stand for in the michaelis-menten equation?

Michaelis constant (where 50% sites occupied)

45

Describe the graph that is extrapolated from the Michaelis-Menten equation?

Rectangular hyperbola

46

Describe the graph between solute uptake vs solute concentration when comparing transport and diffusion?

Diffusion is a straight line while transport is a curve

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47

What are the two outcomes of other substrates being present?

Competitive inhibition or non-competitive inhibition

48

Name the two changes to the Km and Vmax properties for competitive inhibition?

Increase substrate Km Unchanged Vmax

49

Name the two changes to the Km and Vmax properties for non-competitive inhibition?

Decrease Vmax Unchanged Km

50

Name the three types of active transport

Primary Secondary Tertiary

51

What determines what type of active transport is being used?

Look at the coupling to other solute transporter fluxes