DNA opens up and each strand is used as template for a new strand.
Answer:
Answer is B. Positive feedback regulation can generate an abrupt, all-or-none response in which the cell moves from ignoring a signal to responding to it very strongly.
Explanation:
Positive feedback can be described as an example of feedback, which is a natural mechanism that amplifies the action of a system.
It can be better be explained further, as a situation whereby the blood pressure decreases and the response of the body also makes or causes the blood pressure to decrease the more.
Other examples of a positive feedback also include blood clotting, ripening of fruits , uterus muscle contraction, resulting to the stretching of the uterus during pregnancy.
Answer:
The events in chronological order are:
- Abrin is absorbed into the blood and enters the body's cells
- Abrin binds to ribosomes in the cytoplasm
- Abrin inactivates the 28S rRNA in the large subunit of the ribosome.
- Ribosomes are unable to add new amino acids to polypeptides
- Protein synthesis halts in many tissues
- Multiple organ systems fail
- Victim dies
Explanation:
Abrin is a toxic protein obtained from the seeds of Abrus precatorius, it is highly toxic, with an estimated human fatal dose of 0.1-1 microgram/kg, and causes death after accidental and intentional poisoning.
When ingested the abrin would enter the victim's body and travel through the blood and eventually enter a cell's cytoplasm (abrin is absorbed into the blood and enters the body's cells). Once there it would interact with the ribosomes and reacts with them on a molecular level (peptide bond catalytic enzyme) (abrin binds to ribosomes in the cytoplasm), which results in the ribosome exhibiting its toxic response to abrin (abrin inactivates the 28S rRNA in the large subunit of the ribosome). As a result of the ribosome reacting to abrin (ribosomes are unable to add new amino acids to polypeptides), protein synthesis within that cell is affected (protein synthesis halts in many tissues). Once multiple cells are affected by abrin the organ will exhibit its toxic response (multiple organ systems fail), and the victim would die.
