Topic 1:3

Question 1

active transport uses

Answer 1

integral membrane proteins

Question 2

uniport

Answer 2

transport only one ion

Question 3

dual port

Answer 3

transport an ion and something else

Question 4

symport

Answer 4

ion and the other molecule are transported in same direction across the membrane

Question 5

antiport

Answer 5

ion and the other molecule are transported in opposite directions across the membrane

Question 6

3 classes of primary active transport

Answer 6

ATPase ion pumps
ABC system
group translocation

Question 7

ATPase ion pumps transport

Answer 7

ions only

Question 8

ABC systems transport

Answer 8

ions and non ionic molecules

Question 9

group translocation transport

Answer 9

non ionic molecules

Question 10

ATPase ion pumps

Answer 10

3 classes: P-, V-, and F-ATPase Ion pumps
All have one or more binding sites for ATP on cytosolic side of the membrane
Reversibly phosphorylated by ATP
All use conformational change in proteins

Question 11

P class ion pumps

Answer 11

Simplest, dual porter, antiporter
4 transmembrane subunits, two a polypeptides and two B polypeptide
The larger a subunit is phosphorylated (binds PO-4) by ATP during transport
Transported ions move through this subunit
in E1 state, they optimally bind one ion, and in E2 state, they release that ion and bind the other ion to be transported.

Question 12

Na+/K+ -ATPase pump:

Answer 12

crucial for all especially nerve cells; function is to maintain intracellular Na+ low and K+ high 
The hydrolysis (break down) of ATP drives Na+out and K+in: 3 Na+pumped out and 2 K+pumped in.
E1 binds Na+ and E2 binds K+

Question 13

Calcium transport in muscle

Answer 13

in resting muscle cytoplasm must be kept low, calcium ions pumped into sarcoplasmic reticulum, may be Ca++/H+ don’t know yet
2 calcium ions per ATP hydrolysed
E1 binds Ca++ and E2 releases Ca++

Question 14

F class

Answer 14

at least 3 kinds of trans membrane proteins
F-ATP synthase: produce ATP in the process of transporting H+
Bacterial plasma membranes, mitochondria and chloroplasts
Synthesis of ATP from ADP and Pi
ETS pumps H+ from matrix to inter membrane space between inner and outer mitochondrial membranes
Produces steep H+ gradient between inter membrane space and inside of mitochondria
Diffusion of H+ through ATP synthase (down conc. grad.)powers ATP production
(opposite way to other transport proteins)

Question 15

V class pumps

Answer 15

at least 2 kinds of trans membrane proteins
Use ATP to acidify organelles, by pumping H+ into them against the concentration gradient
Both transport only protons (H+)= uniporters
Transport H+ into lysosomes, endosomes, Golgi apparatus and other vesicles to maintain their low pH
Also in osteoclasts and macrophages
Use energy release by ATP hydrolysis to pump H+ from cytosol to exoplasm up the proton electrochemical gradient
Acidify organelles
Osteoclasts: bone cells that break down bone tissue, osteoblasts then build back up
Secrete acid into space between osteoclasts membrane and bone surface, ATP driven proton pump in its membrane secretes the acid

Question 16

ABC systems

Answer 16

3 proteins, binding atp closes channel, breaking down ATP opens channel
Ligand-binding domain restricted to single type of molecule
Binding atp provides energy to pump ligand across membrane
Transports sugar, ion, peptides, polysaccharides and proteins
Pump foreign substances out of cells (defence mechanisms, cancer) - animals, fungi, bacteria

Question 17

Group translocation

Answer 17

No ATP, but high energy P supplied by PEP (active transport)
5 proteins, more important in bacteria
Irreversible and saturable
P group shuttled from enzyme I to the transporter and then to glucose
Substrate gets modified and is trapped inside cell