Saved Bookmarks
| 1. |
a. Write the structure of histidine when pHlt1.82 and pHgt1.82. b. What is the pH range of neutral A A at the isoelectric point? c. The pH range in cellular fluid is 6 to 7. In what form (dipolar,cation, or anion) do the amino acids in each class predomiate in the cell? |
Answer» Solution :a.  b. All those amino acids with neutral `(R )` groups (e.g., hydrocarbon, alcohol, and amide) have `pl` in the same range `5.5-6.3.` c. The amino acids are in the dipolar form because the cellular `pH` is very close to their `PI's`. i. `pl` for acidic `A A's` are in the acidic range `(pH=6-7)`. they act as acids and exist mainly as anions. ii. `pI` for basic A A's are in the basic range `(pH=6.7)`.they accept `H^(o+)` in the cell and exist mainly as cations. iii. `pI` for very WEAKLY acidic `A A'a` e.g., cysteine (with its `SH`) and TYROSINE (with its phenolic `OH`), are in the acidic range `(pH=5-6)`. they are CLASSIFIED with neutral `A A's` |
|