Principles Of Cell And Membrane Function

Question 1

Which phospholipids are primarily located in the outer leaflet of the cell membrane?

Answer 1

• Phosphatidylcholine

- Sphingomyelin

Question 2

Which phospholipids are primarily located in the inner leaflet of the cell membrane?

Answer 2

• Phosphatidylethanolamine
• Phosphatidylserine
• Phosphatidylinositol

Question 3

What is the significance of phosphatidylinositol?

Answer 3

It is a substrate for signal transduction via PLC

Question 4

How does aspirin work to reduce clotting?

Answer 4

Blocking cyclooxygenase

Question 5

How is the rate of Diffusion calculated for substances which diffuse through simple diffusion?

Answer 5

J (Rate) = -P (Permeability) * A (Surface Area) * [Ci-C0] (concentration gradient)

Question 6

What is the partition coefficient (Beta)?

Answer 6

• Used to quantify interactions of molecules within the lipid portion of the bilateral of a membrane
• The more lipid soluble the molecule, the greater the rate of diffusion across the bilayer

Question 7

What is the glycocalyx?

Answer 7

A layer of glycoproteins across the cell membrane which help to trap and digest, protect against toxic substance, or adhere to substances for uptake

Question 8

What is the relevance of the

Nernst equation?

Answer 8

The Nernst equation describes the equilibrium potential for an ion. That is the potential across a
membrane that will produce an electrical force
equal and opposite to the chemical force
produced by the difference in concentration of the
ion across the membrane

Question 9

Explain the role of aquaporins and vasopressin in the renal collecting ducts.

Answer 9

• Cells of the renal collecting ducts contain AQP3/4 in the basolateral membrane
• In the absence of vasopressin, There is no way for water to be reabsorbed into the blood.
• In the presence of vasopressin, AQP is inserted into the apical membrane allowing water to move from urine to blood.
• In the presence of vasopressin, urea recycling is increased

Question 10

What are the two primary ways glucose is transported?

Answer 10

• Facilitated diffusion

- Secondary transport

Question 11

Describe the site and primary characteristics of the GLUT 1 receptor?

Answer 11

• Brain, RBC, Endothelium, Muscle, Adipose

- Broad expression, high affinity

Question 12

Describe the site and primary characteristics of the GLUT 2 receptor?

Answer 12

• Liver, Pancreas, intestine

- Low affinity, high capacity sensor

Question 13

Describe the site and primary characteristics of the GLUT 3 receptor?

Answer 13

• Brain, Placenta, testes

- Primary GLUT in neurons

Question 14

Describe the site and primary characteristics of the GLUT 4 receptor?

Answer 14

• Skeletal/cardiac muscle, adipose

- High affinity

Question 15

Describe the site and primary characteristics of the GLUT 5 receptor?

Answer 15

• Small Intestine, Sperm

* *- Transports fructose

Question 16

What process allows glucose to continually enter the cell by lowering intracellular glucose?

Answer 16

• Conversion Of Glucose to G6P via Hexokinase

Question 17

Describe the pathology of Cystic Fibrosis?

Answer 17

• Autosomal recessive disease
• defect in CFTR which is an ATP binding transporter which functions as a Cl- channel, while also regulating other membrane transporters

Question 18

What is P-g, and what is it’s significance?

Answer 18

• P-glycoprotein or ABCB1
• Common cause of individual variation of response to drugs
• ATP-dependent efflux pump with broad substrate deficiency
• Likely a defense mechanism against toxins

Question 19

Differentiate SGLT1 and SGLT2.

Answer 19

• SGLT1 is in the intestinal mucosa, as well as proximal tubules of the kidney
• SGLT1 is approximately 2% of renal glucose reabsorption
• SGLT2 is 1 Glu/1Na+ transporter, while SGLT1 is 1Glu/2 Na+

Question 20

Describe Why Oral rehydration therapy works for cholera.

Answer 20

• Na+ and Glu are cotransported from the gut to the blood.

- ORT using water with sodium Potassium, and glucose can increase uptake of water.

Question 21

How does caveolae endocytosis differ from many other types of endocytosis?

Answer 21

It is clathrin independent

Question 22

What is 2,4-dinitrophenol?

Answer 22

• Metabolic protein which uncoupled oxidative phosphorylation
• Carries proteins across my membrane
• results in hyperthermia

Question 23

What is Sodium Azide?

Answer 23

• Metabolic poison
• Inhibits Cytochrome C oxidase (Complex IV)
• affects organs with high rates of respiration