Lecture 5

Question 1

ATP?

Answer 1

ATP is the source of energy for use and storage at the cellular level.

Question 2

Structure of ATP?

Answer 2

The structure of ATP is a nucleoside triphosphate, consisting of a nitrogenous base (adenine), ribose sugar, and three serially bonded phosphate groups.

Question 3

ATP -> ADP?

Answer 3

Relases energy

Question 4

ADP -> ATP?

Answer 4

Requires energy

Question 5

What movement requires ATP?

Answer 5

Movement against the concentrtion gradient requires ATP.

Question 6

Symporters and Antiporters use ATP how?

Answer 6

They use ATP in a form called Indirect active transport. This involves coupled transport of a solute S and ions - protons - in this case. The exergonic inward movement of protons provides the energy needed t move the solute S against its gradient or electrochemical potential.

Question 7

Direct active transport uses ATP…?

Answer 7

Direct active transport involves using ATP to directly pump a solute across a mebrane against its electrochemical gradient.

Question 8

Indirect active transport involves?

Answer 8

Indirect active transport involves the transport of a solute in the direction of its increasing electrochemical potential coupled to the facilitated diffusion of a second solute (usually an ion).

• Antiporter and symporter use this method.

Question 9

ATP driven pumps are often called.?

Answer 9

ATP driven pumps are often called transport ATPases becausr they hydrolyze ATP to ADP and phosphate and use the energy released to pump ions or other solutes across a membrane.

Question 10

Examples of ATPases?

Answer 10

P-type pump
ABC transporter
V-type proton pump
F-type ATP synthase

Question 11

P type pumps work how?

Answer 11

A released phosphate group phosphorylates the protein itself and changes the conformation of the channel, allowing items through. Items are typically H, Na, Cl, Ca

Question 12

ABC transporters work how?

Answer 12

They move small molecules. Two identical proteins that come togethet (dimers) and have an ATPase region to hydrolyze ATP. Change in conformation comes from binding of the small molecule

Question 13

V-type proton pump?

Answer 13

Large pumps, move hydrogen ions into lysosomes. Conformational change as a result of ATP hydrolysis.

Question 14

F-type ATP synthase?

Answer 14

Reverse of V-type pump. Makes ATP from ADP + P.

Question 15

Why are they called P-type pumps?

Answer 15

They are called P-type pumps becayse they phosphorylate themselves during the pumping cycle.

Question 16

the four types of p-ATPases?

Answer 16

P1: Transport heavy metals
P2 (important): maintain electrochemical gradients
P3: Membrane potential plants and fungi
P4: Flippase, moves phospholipids
P5: unknown!

Question 17

P-pump inhibitors prevent…?

Answer 17

Proton pump inhibitors present excess stomach acidification (acid reflex is caused because of p-pumps)

Question 18

P2 ATPases we need to know?

Answer 18

Ca/H
Na/K
H/K

Question 19

Ca/H ATPase location and function?

Answer 19

Ca/H ATPases are located in the sarcoplasmic reticulum or plasma membrane, they are founding eukaryotic muscles, and they keep the concentration of calcium low in the cytosol.

• The Ca2+ pump, or Ca2+ ATPase, in the sarcoplasmic reticulum (SR) membrane of muscle cells. The SR is a specialized type of endoplasmic reticulum that forms a network of tubular sacs in the muscle-cell cytoplasm, and it serves as an
  intracellular store of Ca2+.

Question 20

Na/K ATPase?

Answer 20

In the plasma membrane of animals, maintains the membrane potential!

• The Na+/K+ ATPase continually pumps 3 Na+ ions out of the cell and 2 K+ ions into the cell.
• It cycles between two conformations, undergoing large conformational changes through the pumping cycle (look at slide 11)

Question 21

H/K ATPase?

Answer 21

In the plasma membrane of animals, pumps H into stomach to keep it acidic (many of the stomach enzymes only work in acidic environments).

Question 22

Potassium binding sites of Na/K ATPase?

Answer 22

Potassium binding sites of the Na+/K+ ATPase are made
of oxygens

Question 23

Vacuolar ATPase?

Answer 23

● Two rotary motors
● The ATP-driven motor turns an axle, which turns a second motor (light blue and magenta) that pumps
protons across the membrane.
● The linkers hold the complex together
● pumps H+ ions to increase acidity in specific organelles (ie., vacuoles, lysosomes)
● Not phosphorylated
● V-ATPase is regulated by separating the ATP-powered motor from the proton pumping motor.

Question 24

Rotating binding site?

Answer 24

The binding site of the proton pump motor rotates, slowly lowering the binding site until the molecule is diffused out.

Question 25

F-type ATPases are....?

Answer 25

ATP synthases - they make ATP! They use H and are located in the inner mitochondrial membrane of eukaryotes - use H gradient to drive ATP synthesis * ATP synthase moves ions with the concentration gradient to produce ATP.

Question 26

Structure of ATP synthase?

Answer 26

- F0 (in membrane) is an electric motor powered by the flow of H+. - F1 motor (inside membrane) is a chemical motor, powered by ATP. ● The two motors are connected together by a stator

Question 27

F1 motor joins ADP and Pi how?

Answer 27

The F1 motor joins ADP and Pi together by force (like smushing green and blue playdoiugh together)

Question 28

ATP-binding cassettes?

Answer 28

Mediate ATP-powered translocation of many substrates across membranes. - They contain and ATP-binding cassette - Two conformation states - Heterodimers (very similar) - Importers and exporters - Some need binding protein - Move items larger than ions

Question 29

ABC transmembrane domains?

Answer 29

ABC transporters have two transmembrane domains (TMDs) that are embedded in the membrane bilayer and two ABCs in the cytoplasm. - They undergo conformational change due to hydrolysis of ATP

Question 30

ABCs are conserved?

Answer 30

An ATP-binding cassette is a conserved protein domain. They are different molecules of course, but: - ALL ABC transporters have a shared amino acid sequence in the ABC domain.

Question 31

Missing protien in white fly mutant?

Answer 31

The missing protein in the white fly eye mutant is an ABC transporter (cannot move pigment due to missing ABC transporter) . - Solidifies the idea that ABC-type ATPases transport big molecules: metabolites drugs, amino acids, sugars, peptides, and pigment precursors.

Question 32

Heterodimerization of ABC ATPases?

Answer 32

Heterodimerization of ABC ATPases increase the number of solutes: super critical where this type moves larger molecules and diverse molecules.

Question 33

Example using pigments?

Answer 33

White forms heterodimers with two other proteins Scarlet and Brown * Heterodimers have different solutes * Therefore, a relatively small amount of ABC transporter move a large number of solutes by employing heerodimerization!