Biologia

CELL DIVISIONS
* The regular sequence, growth and division is called cell cycle.
* Cell cycle stages:
1. Interphase: growing, copying DNA. Replication is the process in wich the nucleusmakes an exact copy of the DNA. And prepares for division.
2. Mitosis: The cells nucleus divides into 2 new nuclei.
a. Prophase: chromatin in the nucleus condenses to form chromosomes.Nuclear envelope disappears.
b. Metaphase: Chromosomes line un across the center of the cell. With the centromere attached to a spindle fiber.
c. Anaphase: Half of the chromosomes are pulledto one side of the cell; half go the other way.
d. Telophase: The chromosomes begin to strech out. A nuclear envelope is formed.
3. Cytokinesis: Cytoplasm divides. The organelles aredistributed into 2 new cells.

* DNA replication ensures that each daughter cell (new cell) will have the genetic information needed to do its activities.

* The ladders in the DNA are made up ofdeoxyribose and phosphates.

* The ladres are joined tigether by 4 nitrogen bases:

1. Adenine
2. Thymine
3. Guanine
4. Cytosine

* The 2 sides of the DNA unzips. Nitrogenbases in the nucleus pair up with the bases on the DNA molecule. The order of the bases in each new DNA molecule exactly matches the order in the original DNA molecule.

CANCER
* Is a deseasein with cells grow and divide uncontrollably. Damaging the parts of teh body around them.
* Cancer beins with a mutation, causes a change in the DNA
* First, a cell develops in an abnormalway. As this cells divide it produces more abnormal cells. They form a tumor.
* A tumor is a mass of abnormal cells that develop when cancerous cells divide and grow uncontrolably.
* Somecancerous cells may enter the bloodsteam and Spreads to other areas of the body.
* There are 3 common ways to treat cancer:
1. Surgery: surgery is the first option. They remove the tumor.
2....