Cell Division

 Cells Divide, Divide, & Divide!

Interphase

Step 1: G1 Phase

The cell starts to grow and prepare itself for cell division. 

Step 2: S Phase

The cell has grown enough for it to replicate (copy and paste) its DNA.

Step 3: G2 Phase

The cell keeps growing and preparing for cell division.

Step 4: M Phase

This is where the cell division actually happens. It is divided into 4 stages. The last stage, Cytokinesis is where the cytoplasm divides into two individual cells. 

                                                    What's Cancer?

Cell Cycle is regulated by checkpoints and proteins. 

Mutations in these proteins can lead to cancer.

Cancer is uncontrolled cell growth!

M Phase: Mitosis 

Type of Asexual Reproduction is used to create identical somatic/ body cells for growth, repair, and replace worn-out cells. 

Example: Skin Cells

In Mitosis, the cells made contain the same number of chromosomes (23) as the original cell. Basically, the cell clones itself!

Mitosis has 4 stages

P-prophase

                         Chromosome condenses; nuclear membrane disappears

M-metaphase

                  

                                  Chromosomes line up in the middle

A- anaphase

         Chromatids of each chromosome separate and move to opposite poles

T- telophase

                                Nuclei reform; begin to see two cells

Cytokinesis

Animal Cells have a Cleavage Furrow!  And the two cells COMPLETELY split

Plant Cells have a Cell Plate! The two cells have this border that separates the two but they don't split off. 

Benefits of Asexual Reproduction:

• Produces a LARGE Amount of Offspring 
• Common in unicellular organisms in stable environments
• Also called budding, binary fission, or conjugation
• Very quick process and requires low energy 

                      Con to Asexual: NO genetic diversity!

Final Product: 2 identical daughter cells with 46 chromosomes in each!

M Phase: Meiosis                                        ME= WE

Creates Non-identical sex cells (gametes like sperm and eggs) for Sexual Reproduction. 

Meiosis reduces the number of chromosomes (23) of the original cell (46). So the new 4 cells will have HALF of the parent cell. 

<- RESULT: YES GENETIC DIVERSITY!!

due to the formation of DIFFERENT genetic gametes during Meiosis!

HINT: Unlike in Mitosis, Meiosis Metaphase has DOUBLE Chromosomes lined up!

The two haploid daughter cells go through PMAT2 but:

• NO Chromosomal replication (No Interphase)
• NO Crossing Over
• YES Indpendent Assortment in Metaphase

PMAT2 Is very similar to normal Mitosis!

Final Product: 4 NOT IDENTICAL daughter cells with 23 chromosomes in each!