Kyla Charlize A. Cruz
1. What are the phases of the cell life cycle and events involved in each phase?
Cell cycle leads to the division and duplication of the cell. The stage where a cell grows and duplicates its own DNA is called the INTERPHASE. The interphase is divided into three subphases: G1 phase, S phase, G2 phase.
G1 phase or “First Gap”- the cell grows larger, produces a copy of its organelles and make the molecular building blocks it will need for the later steps.
S phase or “Synthesis”- A complete copy of the DNA in the nucleus is synthesizes.
G2 phase or “Second Gap”- more growth of the cell and production of proteins and organelles, prepares for mitosis
MITOTIC PHASE- cell separates its DNA into two sets and the cytoplasm is divided that forms two new cells. M phase has two division related processes: Mitosis and cytokinesis.
Mitosis- condensation of the nuclear DNA into visible chromosomes that are separated by the mitotic spindles.
Cytokinesis- the splitting of the cytoplasm of the cell that then forms two new cells. Usually starts while the mitosis ends.
2. What stimulates cell division to occur?
Hormones and cytokines are chemical messengers that stimulate cell divisions.
3. What are the types of cell division and how do they differ from one another?
There are three types of cell division: BINARY FISSION, MITOSIS and MEIOSIS
Binary Fission- Single-celled organisms copy themselves for reproduction.
Mitosis- this type of cell division happens in the majority of the body’s cell not including the sperm and egg cells.
Meiosis- This is where the sperm and egg cells divide.
4. What are the five stages of mitosis and the events included in each of them?
– Chromatin fibers coil together more tightly that condenses into discrete chromosomes.
– The disappearance of the nucleoli
– Two identical sister chromatids appear that’s joined in their centromeres
– Mitotic spindles form
– Centromeres move away from each other, parted by the lengthening microtubules
– Nuclear envelope fragments
– Microtubules form each centrosome invade the nuclear area
– Chromosomes become more condensed
– Some microtubules attach to the kinetochore, becoming the “kinetochore microtubules” theses microtubules jerk the chromosomes back and forth
– Nonkinetochore microtubules interact form the opposite pole of the spindle
– Centrosomes are now found at the opposite poles of the cell
– Chromosomes all arrived at the metaphase plate
– Sister chromatids separate from each other and are pulled towards the opposite end of the cells.
– By the end of this phase, the two ends of the cell have complete collections of chromosomes.
– Two daughter nuclei form in the cell
– Nuclear envelopes arise
– Nucleoli reappear
– Chromosomes return to their stringy form
5. How does a healthy cell develop into an abnormal cancer cell?
Out of control cell growth causes cancer. The different cells affected determine the type of cancer produced. Cells divide uncontrollably then form lumps of tissues also known as tumors.