Tutor profile: Ashna G.

Write about anything that delights you.

Throwing a penny in a fountain It delights me so when I see a child throwing a penny in a fountain full of pennies. At first all it seems to be is a kind of basic ritual: a child places a brown-green rusted copper penny on the nail of their thumb. Their index finger rests on the tip of their thumbnail and their thumb flicks up against the index finger, launching the penny into the fountain. But what makes this moment so delightful is a hopeful child making a wish as they launch a penny into a fountain of pennies launched by other hopeful children. It’s the precious moment after, when a child eagerly waits for their wish to finally come true. The penny a parent could have used to pay off the $31.01 spent on groceries, is given to a child to fill them with excitement and hope.

What are receptors? Name the major receptor types and explain how drugs interact with them.

Receptors are usually found on cell surfaces and bind to ligands which cause responses in the immune system. • Drugs can inhibit/enhance the flow of ions by opening/closing Ligand Gated Ion Channels (iontropic), which change polarity of the cell, directly affecting cell activity. Drugs can block or enhance the release of neurotransmitters or work on receptors that activate or inhibit effect of neurotransmitters. • GPCRs are a very common drug target and when activated releases secondary messenger cAMP. When bound to a ligand, GDP is converted to GTP and ATP is used to make cAMP. Drugs can mimic ligands to activate GPCRs or block GPCRs to prevent the release of cAMP. • Nuclear Receptors sense thyroid and steroid hormones, which regulate the expression of certain genes. Drugs can mimic the hormone or block its effects. • Kinase linked receptors are also enzymes. When bound to a ligand, receptors are phosphorylated and active. Drugs can bind to either active or allosteric site (inhibitory or activator site) to release cytokine growth factor hormones or block their effects.

Simplify: (2x-3y4)3(x3 + y)0 / (4xy-2)3

(1/8)(y^18 / x^12)