Quiz 5

Question 1

Describe P-Type ATPase pumps

Answer 1

P-type ATPase pumps are a type of pumps that phosphorylate themselves, by taking a phosphate from ATP, in order to move a molecule across a membrane

Question 2

Describe an ABC transporter

Answer 2

ABC transporters (ATP-binding Cassette) consume 2 molecules of ATP per “round” of molecule movement bc of their identical domains (of a transmembrane and cytosolic domain)

Question 3

Describe a Secondary Transporter

Answer 3

Secondary transporters use a concentration gradient that is previously established via primary active transporters

This allows secondary transporters to move “high value stowaway” molecules across a membrane

Question 4

Describe an Ion channel and include the 2 “important pieces” these include

Answer 4

Ion channels use a selectivity filter to allow specific ions into the transmembrane protein and are then stimulated to open their “gate” via 1. voltage 2. a ligand or 3. stress (mechanical)

1. Selectivity filter
2. Gate

Question 5

Describe a Gap Junction

Answer 5

Gap junctions have no specificity filter and allow cytoplasm sharing between neighboring cells via “connexons” that form pores between cells

Question 6

Describe an Aquaporin

Answer 6

Aquaporins allow water through but NOT ions

Question 7

State and describe the 2 “states” that you can find P-type ATPases in. Describe the relationship between these 2 states

Answer 7

E1 state: open to the inside of the cell

E2 state: open to the outside of the cell

P-type pumps switch between these 2 states when they phosphorylate themselves
“take in something from the inside, phosphorylate, and release it to the outside”
(sort of how a canal lock system works with boats)

Question 8

Name the type of transmembrane protein that can exist in a monomer and homodimer. Explain these 2 different structures.

Answer 8

ABC transporters can be either monomers or homodimers

Monomers: each transporter is a single unit with 2 transmembrane domains and 2 cytosolic domains

Homodimers: Each transporter is composed of 2 “twin” subunits
(each subunit has 1 transmembrane domain and one cytosolic domain)

(both monomers and homodimer transporters have 4 total domains)

Question 9

Name the 2 primary active transporters we have discussed that will eventually set up a gradient for secondary active transport processes

Answer 9

P-type pumps

ABC transporters

(both use ATP)

Question 10

True or False:

Primary and secondary active transport both use ATP to move a molecule, thats why they are both forms of active transport. explain.

Answer 10

FALSE

Primary active transport uses ATP but Secondary active transport does not use ATP

However, they are both considered to be “active” forms of transport because they are moving a molecule across a membrane AGAINST it’s own concentration gradient.
(NOT bc of ATP use)