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Hi all, I thought I'd go over a few important concepts in first year biology;)
Interphase; Time taken between successive mitotic phases, and ranges from as short as 8 minutes (fly embryos) to as long as few years (humans). Try to associate the word "Interphase" with inter-( to get in)+ phase (state or form) before mitosis takes place. Interphase, is the most abundant of all phases. Most cells spend interphase as their dominant life for metabolism and continue to exist with functions that sustain them through interphase.
You will notice that, in the picture above, chromatin has not condensed and is floating at the center of cell. This means that they are still functional as individual cell and they do not have the need to replicate at the moment.
Cells undergoing interphase only show growth, and do not show any indications of cell activities otherwise considered with different names.
Now up until here you've covered the most basics of interphase, which is the state where cells only display growth and not any particular activities of interest(such as replicating). Let's divide the interphase into 3 different periods. They all branch out (as in most phases).
G1; This very first period of interphase carries some inheritance from previous fecund cell activities. Also this is a period where the metabolic activity of the cell experiences a rapid growth, and this results in replication of centrosomes. Just to recap, centrosomes are composed of a pair of centrioles, and in essence in G1 centriole duplicates to create another pair and thereby double. This process leads up to what's called S phase of the interphase.
For those living in Canada think of G1 as more like a car license where you are partially qualified to drive but not really hit the high way. Likewise G1 interphase process is more like a prepare-for-all type of thing that leads up to S phase, where more complicated process (think of it as an upgrade) takes place.
S; Long story short, chromatin replicates so that genetic copies are made. Think of this as clone-making, except that there are two sets of DNA available for another cell. It would be cool if we can replicate our selves and biology says it's possible. Ha, another Jack Harper to be made for those Tom Cruise fanXD
G2; That's right folks, you got the G2 car license alreadyXD It's exactly final preparations are made prior to mitosis, where replication into two cells occurs. Think of this process as where you are fully mature and ready for the world to divide yourself into multiple cells depending on the type of mitosis you will be undergoing.
Once they are done with interphase the cells move onto different phases starting from prophase, prometaphse, metaphase, anaphase and telophase. Cytokinesis occurs during the metaphase and that's when the two chromosomes are arranged in two fold like manner at different poles and cleavage furrows just beneath the plasma separate those cells into being two.
It's also note worthy that once the chromosomes have relocated to different poles they are already considered separated.
You can also explain about the G0 phase...:)
Its also great to know the the entire process has been simplified by explaining it with day 2 day examples! Good job! Hats Off!