Answer to Question #98525 in Cell Biology for Abhishek

Question

BRIEFLY EXPLAIN THE FOLLOWING ;

(a) RNA PROCESSING IN EUKARYOTES
(b) CELL CYCLE
(c) SIGNALLING MEDIATED BY INTRACELLULAR RECEPTORS

Answer 1

a) RNA PROCESSING IN EUKARYOTES - this feature involves post transcriptional modification in pre m RNA transcript. It involves- addition of 5 `methyylguanosine cap to the 5` end, addition of about 25 to 250 adenylate residues the step being called as polyadenylation and finally removal of non coding sequences called exons and joining all the coding sequences end to end i.e exons.

(b) CELL CYCLE - is the series of events that take place in a cell leading to duplication of its DNA .It is divides into-

G1 phase- which is the growth phase

S phase- DNA synthesis phase

G2- Growth and preparation of mitosis

M - mitotic phase divided into prophase, metaphase, anaphase and tellophase

(c) SIGNALLING MEDIATED BY INTRACELLULAR RECEPTORS-Intracellular signaling is an important mechanism by which cells can respond to their environment and extracellular cues. Intracellular receptors are present inside the cell in the cyto[plasm or the nucleus.For example steroid hormone receptors are present inside the cell. These hormones easily pass through the plasma membrane and reach inside the cells and joins with their receptors. When the binding occurs it makes its effects slowly by changing transcription and thereby affecting translation of desired proteins.