Week 6: Membrane Transport

Question 1

Delta G Equation

Answer 1

Delta G+RTln(C^cD^d/A^a*B^b)

Question 2

Delta G*’ Equation

Answer 2

-RTlnK

Question 3

Rxn graph drawbacks and what it is

Answer 3

Single-molecule consideration
Not good for looking at entire mixtures
Quadratic graph

Question 4

What does delta G = 0 mean

Answer 4

At equilibrium (minimum of the curve)
(Upside down quadratic)

Question 5

What does Delta G* mean for difusion

Answer 5

Is not equal to 0

Question 6

What is the normal ratio for delta G equation

Answer 6

Inside/outside

Question 7

Why is the ratio inside/outside

Answer 7

You are calculating delta G of flow into cell
If they were switched would be calculating flow out of cell

Question 8

Movement of molecules down a concentration gradient is what?

Answer 8

Spontaneous

Question 9

Delta Gt equation

Answer 9

RTln(in/out) + ZFdeltaPsi

Z = the charge on the particle (either - or +)
Delta Psi is calculated by Psi(in)-Psi(out)

Question 10

Where are cells more negative

Answer 10

On the inside

Question 11

Secondary Transport

Answer 11

2 different proteins/pumps
One uses ATP
Other uses the concentration gradient created by the first

Question 12

Sodium Potassium Pump

Answer 12

Use the energy of ATP hydrolysis to pump 3Na+ out of cell and 2+ K into the cell against their concentration gradient

Question 13

What does all of the work of the Na+-K+ pump

Answer 13

The alpha subunit
4 domains in the alpha subunit

Question 14

Signaling Proteins Steps

Answer 14

1.) Release of a Primary Messenger
2.) Reception of the primary messenger
3.) Generation of an intracellular 2nd messenger
4.) Activation of effector results in a physiological response
5.) Termination of signal cascade

Question 15

1.) Release of Primary Messenger
2.) Reception

Answer 15

Ghrelin(hunger, stomach)
Glucagon (Glucose breakdown liver)
Receptor Protein in cell, reversible

Question 16

3.) Generation of an intracellular 2nd Messenger

Answer 16

Receptors change protein structure
Generates a 2nd messenger in the cell (Ca2+, cAMP)

Question 17

4.) Activation of effector results in a physiological response
5.) Termination of signal cascade

Answer 17

2nd messenger is going to cause a chemical change that will cause an enzyme to start or stop some metabolic process

Question 18

Primary Messengers

Answer 18

Hormones
Photons
Neurotransmitters

Question 19

How many classes of Receptors

Answer 19

3 Major Classes

Question 20

3 Classes of Receptors

Answer 20

7-Transmembrane-Helix Receptors: Heterotrimeric G-Proteins
Dimeric membrane receptors: Recruit protein kinases
Dimeric protein receptors: Are protein kinases

Question 21

Secondary Messengers

Answer 21

cAMP
cGMP
Calcium Ion
IP3

Question 22

Examples of Dimeric membrane receptors that recruit protein kinases

Answer 22

Human Growth Hormone Receptor

Question 23

Protein Structure of 7TM

Answer 23

Tertiary Structure Change

Question 24

Protein Structure of Dimeric

Answer 24

Quaternary Structure Change

Question 25

Dimeric Protein Receptors that are Protein Kinases

Answer 25

Epidermal Growth Factor
Insulin Receptor

Question 26

RAS Protein

Answer 26

Key Component of EGF Pathway
Member of family of signal proteins called small G proteins or small GTPases
Monomeric (Not Heterotrimeric like normal G proteins)
Active: Bound to GTP
Inactive: Bound to GDP
Has Intrinsic GTPase Activity (Automatically hydrolyze a P off GTP to GDP)

Question 27

Insulin Signaling

Answer 27

Insulin hormone is secreted from the pancreas when blood glucose level is high
Biochemical signal for fed state
2 polypeptide chains linked by disulfide bonds
Insulin receptor is a receptor tyrosine kinase
Receptor exists as a dimer even in absence of insulin

Question 28

Kinase Cascade

Answer 28

Insulin Binding to Conformational change(quarternary) to Cross-Phosphorylation of the kinase to phosphorylation of IRSs
Phosphorylated IRSs are adaptor proteins to convey the insulin signal
Phosphoinositide 3 Kinase binds to IRS and catalyzes PIP2 to PIP3
PIP3 activates PIP3 dependent kinase, which activates AKT
AKT phosphorylates enzymes that control the glucose transporter, increasing glucose uptake by cells, as well as enzymes that convert glucose to glycogen

Question 29

Signal Termination

Answer 29

Protein phosphatases remove P from activated proteins, ending the signal
Lipid phosphatases remove P from PIP3 to PIP2

Question 30

Steps for Sodium-Potassium ATPase Mechanism

Answer 30

1.) 3 Na ions bind
2.) Phosphorylation of an Asp residue
3.) Conformation change release 3 Na ions outside of the cell
4.) 2 K Ions binds
5.) Release of the phosphate group
6.) 2 K ions are released inside the cell

Question 31

Steps for G Protein-Coupled Receptor Pathway

Answer 31

1.) Initiation
2.) Ligand Binds to Receptor
3.) Conformational change of the receptor
4.) Dissociation of Beta and Gamma subunits of the G protein
5.) Exchange of GDP for GTP in the G protein
6.) Adenylate cyclase converts ATP to cAMP
7.) Kinase protein is activated to phosphorylate targets
8.) Termination

Question 32

Activation of a G protein in response to hormone binding requires the binding of what

Answer 32

GTP. to the Alpha subunit

Question 33

What binds to G-Proteins

Answer 33

GPCR
GDP
GTP

Question 34

What doesn’t bind to G-Proteins

Answer 34

cGMP
It is a secondary messenger

Question 35

Not secondary messenger

Answer 35

Epinephrine