Primary And Secondary Active Transport

Question 1

Primary active transport

Answer 1

Driven directly by hydrolysis of ATP

ATP hydrolysis catalysed by transporter

Question 2

Primary active transporter examples:

Answer 2

Ca2+ ATPase (plasma membrane, drives Ca out cell)

F1F0 ATPase (ATP synthetase, reverse mode, uses H ions from ETC chain to produce ATP)

Na+K+ ATPase

Question 3

Co transport

Answer 3

More than one type of ion or molecule transported on a membrane per reaction

Question 4

Types of transporter

Answer 4

UNIport - one molecule through

SYMport - 2 molecules same direction

ANTIport - two molecules opposite directions

Question 5

Na+ K+ ATPase actions

Answer 5

3 Na out
2 K into cell

(Antiporter)

Question 6

What is type of ATPase is Na+K+ATPase and why?

Answer 6

P-type

ATP phosphorylates aspartate and produces phosphoenzym

Question 7

What percent of BMR is used for Na+K+ pump?

Answer 7

25%

Question 8

Structure of sodium pump

Answer 8

A subunit - binding sites for Na, K and Ouabain (inhibitor)

B subunit - glycoprotein that directs the pump to surface

Question 9

What is the sodium pump important for?

Answer 9

Generating ion gradients to allow secondary transport

Creates high intracellular K+ - when diffuses out of cell via channels contributes to membrane potential

Question 10

How much does the sodium pump actually contribute to membrane potential?

Answer 10

Only -5 to -10 mV
SMALL
High intracellular K more important

Question 11

Secondary active transport

Answer 11

Driven indirectly by energy released of hydrolysis of ATP

Dissipation of gradients formed by another ion or substance provides energy for secondary active transport

Question 12

Secondary active transport example

Answer 12

Na+K+ATPase pumps sodium out of cell

High concentration of sodium outside cell

Na+Ca2+ exchanger allows 3Na+ in and 1 Ca2+ out
(Antiport)

Question 13

Importance of Na+K+ ATPase and type

Answer 13

Maintain cellular concentrations of Na+ and K+

Antiporter

Question 14

Na+Ca2+ importance and type

Answer 14

Inward flow of Na (from sodium pumping out to create gradient) drives OUTWARD flow of Ca2+ up concentration gradient

Antiport

Question 15

Na+ H+ exchange importance and type

Answer 15

Inward flow of Na (from sodium pumping out to create gradient) leads to outward flow of H+
= alkalisation
Antiport

Question 16

Na+glucose co transport importance and type

Answer 16

Small intestine and kidney
Inwards flow of Na provides energy for glucose to go against concentration gradient

Symport

Question 17

Examples of transporters in medicine (CFTR)

Answer 17

Cystic fibrosis - sodium pump creates gradient
Na+, 2Cl-K+ transporter allows all into cell
Potassium and sodium re used in pumps
Cl leaves via CFTR
mutation = CFTR doesnt work so no Cl leaves so no water leaves
= thick non motile mucus

Question 18

Diarrhoea transporters

Answer 18

Sodium pump creates gradient 
Na+Cl-K+ enters cell via transporter 
Na and K leave 
Cl leaves via CFTR
Vibrio cholera activates protein kinase
Phosphorylates CFTR 
Increased activity 
More Cl leaves so more water leaves