-ANSWER EACH QUESTION IN 1 PARAGRAPH. EACH ANSWER CANNOT EXCEED MORE THAN HALF A
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-ANSWER EACH QUESTION IN 1 PARAGRAPH. EACH ANSWER CANNOT EXCEED MORE THAN HALF A PAGE.
-PROVIDE TWO REFERENCES FOR EACH ANSWER (NO WIKIPEDIA!). USE A CITATION FORMAT OF YOUR CHOICE AND BE CONSISTENT.
1. (a) Discuss the permeability of biological membranes as a function of hydrophilicity / lipophilicity of solute molecules.
(b) Discuss the permeability of biological membranes as a function of a solute molecule size.
(c) What is the approximate molecular weight above which the permeation of water-soluble substances by diffusion occurs at negligible rates?
(d) How do water-soluble molecules that are much larger than this cut-off enter and leave the cell?
2. The poison cyanide acts by binding irreversibly to one of the components of the electron transport chain, blocking its action. As a result, the entire electron transport process comes to a screeching halt and the cells lose 94% of their ATP-producing capacity. Considering the types of cellular activities that depend on energy expenditure, what would be the consequences of cyanide poisoning?
3. Briefly discuss gene therapy and describe 2 potential clinical applications
Explanation / Answer
1.a)some molecules can pass through cell membranes because they dissolve in the lipid bilayer. Such molecules are called lipophilic molecules.The steroid hormones provide a physiological example. These cholesterol relatives can pass through a membrane in their path of movement, but what determines the direction in which they will move? Such molecules will pass through a membrane located down their concentration gradient in a process called simple diffusion. phospholipids are both hydrophilic (water-loving) and phydrophobic (water-hating). Because the cell membrane is composed of 2 layers of phospholipids (called the lipid bilayer), the inside of the membrane is hydrophobic, while the outside is hydrophilic
b)The plasma membrane is differentially (selectively) permeable Some substances can move across the membrane and some cannot . Macromolecules cannot diffuse across the membrane because they are too large. Ions and charged molecules cannot cross the membrane because they are unable to enter the hydrophobic phase of the lipid bilayer.Macromolecules can cross a membrane when they are taken in or out by vesicle formation . Ions and molecules like amino acids and sugars are assisted across by one of two classes of transport proteins. Carrier proteins combine with an ion or molecule before transporting it across the membrane. Channel proteins form a channel that allows an ion or charged molecule to pass through.
c)approximate molecular weight above which the permeation of water-soluble substances by diffusion occurs at negligible rates is above 200 molecular weight impermeable
d)Water-soluble molecules larger than 200 molecular weight may cross biologica lmembranes via specific channels or carriers formed by membrane proteins.
3)Gene therapy is an experimental technique that uses genes to treat or prevent disease. In the future, this technique may allow doctors to treat a disorder by inserting a gene into a patient’s cells instead of using drugs or surgery. Researchers are testing several approaches to gene therapy, including:
Replacing a mutated gene that causes disease with a healthy copy of the gene.
Inactivating, or “knocking out,” a mutated gene that is functioning improperly.
Introducing a new gene into the body to help fight a disease.
Although gene therapy is a promising treatment option for a number of diseases (including inherited disorders, some types of cancer, and certain viral infections), the technique remains risky and is still under study to make sure that it will be safe and effective. Gene therapy is currently only being tested for the treatment of diseases that have no other cures.
The number of gene therapy protocols for the treatment of cancer is growing rapidly. The most common type of approved clinical trial for cancer gene therapy involves the ex vivo gene transfer of cytokine genes (e.g., tumor necrosis factor, interleukin-2, granulocyte-macrophage colony-stimulating factor) into tumor cells
Primary immunodeficiencies (PIDs) have represented a paradigmatic model for successes and pitfalls of hematopoietic stem cells gene therapy. First clinical trials performed with gamma retroviral vectors (-RV) for adenosine deaminase severe combined immunodeficiency
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