Answer and Explanation:
The interphase is the previous step before mitosis occurs. The interphase is conformed of the G1, S, and G2 stages.
- During the G1 stage, it occurs a high intense biochemical activity. The cell duplicates its size, and the organelles and other molecules and cytoplasmatic structures duplicate too. Some structures, such as microtubules and actin filaments, are synthesized from zero. The endoplasmic reticulum increases in size and produces a membrane for the Golgi apparatus and vacuoles, lysosomes, and vesicles. During this stage, the pair of centrioles separate, and each centriole duplicates. Mitochondria and chloroplasts also replicate.
The stages S and G2 follow the G1. Once the whole interphase is completed, mitosis occurs.
- During the S stage occurs the DNI replication process. At this point, it also occurs the synthesis of histones and other associated proteins. This is the only stage where the DNI molecule is replicated.
- G2 stage is the final one before the cellular division. Here it begins the slow process of DNI condensation. Duplication of centrioles completes. Structures such as spindle fibers are assembled.
They both need nutrients to carry out life functions
Answer:
The order must be K2→K1, since the permanently active K1 allele (K1a) is able to propagate the signal onward even when its upstream activator K2 is inactive (K2i). The reverse order would have resulted in a failure to signal (K1a→K2i), since the permanently active K1a kinase would be attempting to activate a dead K2i kinase.
Explanation:
- You characterize a double mutant cell that contains K2 with type I mutation and K1 with type II
mutation.
- You observe that the response is seen even when no extracellular signal is provided.
- In the normal pathway, i f K1 activat es K2, we expect t his combinat ion of two m utants to show no response with or without ext racell ular signal. This is because no matt er how active K1 i s, it would be unable to act ivate a mutant K2 that i s an activit y defi cient. If we reverse the order, K2 activating K1, the above observati on is valid. Therefore, in the normal signaling pathway, K2 activates K1.
