The Cell Cycle

1. The Cell Cycle

2. The life of the Cell: Just like an organism the cells also 
have a life cycle. Each cell is made to 
be a copy of its parent cell. The cells 
then live, reproduce and then die.

3. The Cell Cycle: This term refers to the stages of a cells life:  A new cell is created.  The cell lives and has a specialized 
 function.  The cell reproduces another cell.  The cell dies.

4. Chromosome: They are structures found within the cells 
nucleus in eukaryotic cells. They contain the cells DNA (genetic 
information) They are made of DNA and protein Prokaryotic cells have DNA also but they 
may not have a nucleus. When this happens 
the DNA clumps together and floats in the 
cytoplasm.

5. Making More prokaryotic cells: Prokaryotic cells are single cell 
organisms such as bacteria and fungus. They can have either DNA or RNA 
(ribonucleic acid) These cells divide through a process 
known as Binary Fission.

6. This picture shows how binary fission works for 
bacteria. 1. The parent cell begins the process of cell division. During this process the inner layer of the cell membrane begins to fold inwards. 2. The cell membrane continues the process of folding inwards till the inner membrane is completely divided. During this process, the cell also divides its DNA. Each new cell will receive an exact copy of the parent cell DNA. 3. Once the inner cell membrane has completely divided, the outer cell membrane begins the process of dividing. At the end of this step there will be two completely new cells. Each new cell will have an exact copy of the DNA of the parent cell.

7. Eukaryotic cells and their DNA These are multicellular organisms. Each type of organism will have different 
number of chromosomes. All of their chromosomes come in pairs. The pairs of chromosomes are usually 
identical pairs, with similar sequence of 
genes and structures, known a 
homologous chromosomes.

8. Human body cells have 46 chromosomes and 23 
homologous pairs.

9. Eukaryotic cell cycle: Has three main stages. Stage I is called interphase During interphase, the cell grows and copies its 
organelles and chromosomes.  The two copies of a duplicated chromosome are 
known as chromatids. Chromatids held together in a region known as the 
centromere.The joined chromatids then twist and coil 
and twist into the shape of an X.

10. During Stage II the chromatids separate during a process known as mitosis. During Stage III the cell splits into two cells which are identical to each other and to the original parent cell. This Stage is called Cytokinesis.

11. Mitosis: This process happens in every cell of your body 
except the cells of the reproductive system. Interphase: Before mitosis begins the 
chromosomes are copied. Each chromosome is 
then two chromatids.

12. Mitosis Phase 1 (Prophase): This is the first step of mitosis. During this 
step the nuclear membrane disappears 
and the chromosomes clump and coil 
together as rodlike structures.

13. Mitosis Phase 2 (Metaphase) During this phase the chromosomes line up 
along the middle of the cell and begin to pair 
up so they can create homologous pairs.

14. Mitosis Phase 3 (Anaphase): The chromatids separate at the centromere and 
move to opposite sides of the cell.

15. Mitosis Phase 4 (Telophase): A nuclear membrane forms around each 
set of chromosomes and the 
chromosomes unwind. Mitosis is now 
complete.

16. Cytokinesis: After the mitosis is complete two new 
cells have formed. In organisms that do 
not have a cell wall the cell membrane 
simply pinches to separate the two new 
cells. In the cells that have a cell wall a cell plate 
is formed between the two new cells.