PHASES OF THE CELL
1. INTERPHASE:
- G1 Phase (primary growth) :
The G1 phase, or Gap 1 phase, is the first of four phases of the cell cycle that takes place in eukaryotic cell division. In this part of interphase, the cell synthesizes mRNA and proteins in preparation for subsequent steps leading to mitosis. G1 phase ends when the cell moves into the S phase of interphase.
- S Phase (genome replicated) :
S-phase (synthesis phase) is the part of the cell cycle in which DNA is replicated, occurring between G1 phase and G2 phase. Precise and accurate DNA replication is necessary to prevent genetic abnormalities which often lead to cell death or disease
- G2 Phase (secondary growth) :
G2 phase, or Gap 2 phase, is the third and final subphase of Interphase in the cell cycle directly preceding mitosis. It follows the successful completion of S phase, during which the cell's DNA is replicated.
CONCLUSION: There are a few steps that applies before a cell proceed a process called mitosis. There are 3 steps which includes Interphase, Mitosis, then cytokinesis. A cell mostly spend most of their time in the first step which is the interphase. It occurs before the mitosis begins, and it includes G1 phase or primary growth, S phase or genome replicated, and the last one is G2 phase or secondary growth. The first one which is the G1 phase is where there's a growth;increase in size,new proteins and organelles has made. The next one is the s phase where DNA Synthesis-synthesizing (replicating) DNA-occurs in nucleus, and the last one is the G2 phase is where growth and preparation for cell division (lower SA to V so the cell can become bigger). Basically, in the Interphase is most where the chromosomes are copied or doubles; to make more cells. Chromosomes appear as threadlike coils at the start but when each chromosome and it's copy (sister chromosome) change to sister chromatids at end of this phase.
2 Mitosis; Prophase, Anaphase, Metaphase, Telophase, Cytokinesis.
- Prophase:
Prophase is the first phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. During prophase, the complex of DNA and proteins contained in the nucleus, known as chromatin, condenses. The chromatin coils and becomes increasingly compact, resulting in the formation of visible chromosomes. Chromosomes are made of a single piece of DNA that is highly organized.
- Metaphase:
Metaphase is the second phase of mitosis, the process that separates duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. During metaphase, the cell's chromosomes align themselves in the middle of the cell. The chromosomes, which have been replicated and remain joined at a central point called the centromere, are called sister chromatids.
-Anaphase:
Anaphase is the third phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. Before anaphase begins, the replicated chromosomes, called sister chromatids, are aligned at along the equator of the cell on the equatorial plane. The sister chromatids are pairs of identical copies of DNA joined at a point called the centromere.
- Telophase:
is the fourth and final phase of mitosis, the process that separates the duplicated genetic material carried in the nucleus of a parent cell into two identical daughter cells. Telophase begins once the replicated, paired chromosomes have been separated and pulled to opposite sides, or poles, of the cell. During telophase, a nuclear membrane forms around each set of chromosomes to separate the nuclear DNA from the cytoplasm. The chromosomes begin to uncoil, which makes them diffuse and less compact.
-Cytokinesis (occurs after the mitosis):
Cytokinesis is the physical process of cell division, which divides the cytoplasm of a parental cell into two daughter cells. It occurs concurrently with two types of nuclear division called mitosis and meiosis, which occur in animal cells. Mitosis and each of the two meiotic divisions result in two separate nuclei contained within a single cell. Cytokinesis performs an essential process to separate the cell in half and ensure that one nucleus ends up in each daughter cell.
CONCLUSION: The conclusion is that as it was said in the previous page that in the phases of the cell cycle, there are 3 steps that occur. The first one is the Interphase which was explained below. The second one is the mitosis. It consist of four steps which started by the prophase where the Mitosis begins and the cell begins to divide each other or can also be called Centrioles. Then there are poles that appear and begin to move to the opposite end of the cell. The last step in prophase is Spindle Fibers where it started to form between the poles. The second step of mitosis is that metaphase where Chromatids (or pairs of chromosomes) attach to the spindle fibers. The third step of mitosis is called anaphase, its where Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. The fourth and final phase of mitosis is called telophase. It's where Two new nuclei form, and chromosomes appear as chromatin (threads rather than rods). Mitosis ends. After the mitosis ends, there are cytokinesis where Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical structure.
3. Chromosome:
A chromosome is a packaged and organized structure containing most of the DNA of a living organism. DNA is not usually found on its own, but rather is structured in long strands which are wrapped around protein complexes called nucleosomes, which consist of proteins called histones. The DNA in chromosomes serves as the source for transcription. Most eukaryotic cells have a set of chromosomes (46 in humans) with the genetic material spread among them.
4. Chromatid:
one of two identical chromosomal strands into which a chromosome splits longitudinally preparatory to cell division.
5. Centriole:
Every animal has two small organelles called centrioles. They are there to help the cell when it comes time to divide. They are put to work in both the process of mitosis and the process of meiosis. You will usually find them near the nucleus but they cannot be seen when the cell is not dividing.