What natural substances bind opioid receptors in a normal situation? What is the effect of this on the brain?

1. Cystic Fibrosis is a genetic disease, in which a gene has a mutation.
a. What is the effect on the CF protein and why? CF occurs because of mutations in the gene that makes a protein called CFTR (cystic fibrosis transmembrane regulator). A person with CF produces abnormal CFTR protein — or no CFTR protein at all, which causes the body to make thick, sticky mucus instead of the thin, watery kind
b. The CF protein is an ion transporter, important for facilitated diffusion of Cl- ions out of the cell. Where in/on the cell is this located? Can Cl- ions move out of the cell without this protein? Why/why not? (your answer should include something about polar molecules).
c. Based on the answer to (b) above, you would expect the osmotic gradient of these cells to change. What happens to osmosis and why?
d. This leads to very thick mucus in the patient’s lungs. Why?
2. One function of membrane proteins is to function as receptors for extra cellular signals. This function will be highly relevant to many topics in A&P I and II. For example, opioid receptors function in the brain. Referencing the analogy of the “lock and key”, explain the following:
a. What natural substances bind opioid receptors in a normal situation? What is the effect of this on the brain?
b. What happens when heroin binds these opiod receptors in the brain? How is this different than the “normal ligand” for these receptors?
c. What is the effect of Narcan on binding of heroin to opiod receptors? Explain how this makes it possible for Narcan to reverse a heroin overdose.
3. The cell cycle must be tightly regulated and must occur correctly. When problems occur in the cell cycle, abnormal growth can occur. Mutations in specific genes can cause problems in proteins important for cell cycle regulation. BRCA-1 was the first “breast cancer” gene found by researchers and is important for allowing “DNA repair” after replication.
a. In which phase of the cell cycle is BRCA-1 important? Explain your answer.
b. If one copy of the BRCA-1 gene is mutated, why would a patient have an increased risk of cancer?
c. Is BRCA-1 considered a tumor suppressor gene or a proto-oncogene? Explain your answer.
d. Patients with a BRCA-1 mutation may elect to have a double mastectomy and/or a hysterectomy even if there is no evidence of BRCA related cancer in their body. If you had a patient with a BRCA-1 mutation, would you counsel them to have a surgery such as this? Support your answer.
4. Hutchinson-Gilford Progeria occurs when the protein important for stabilizing the nuclear membrane is defective.
a. What do you think would happen to these cells? Why?
b. What problem does the patient have and why?
c. Is this disease passed down directly from parent to child? Support your answer.

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