BIOTECH REVIEWER

CELL DIVISION REVIEWER

1. Cell Cycle

The cell cycle is the process where a cell grows, prepares for division, and divides into new cells.

Two Main Parts

1. Interphase

2. Mitotic Phase (Mitosis + Cytokinesis)

INTERPHASE

Interphase is the longest stage of the cell cycle where the cell grows and prepares for division.

Stages of Interphase

G1 (Gap 1)

• Cell grows

• Organelles increase

• Normal cell functions occur

S Phase (Synthesis)

• DNA is replicated

• Chromosomes are copied

G2 (Gap 2)

• Cell prepares for mitosis

• Proteins and organelles are produced

📌 Key Idea:
During interphase, the cell does not divide yet, but prepares for division.

MITOSIS

Mitosis is the process where the nucleus divides, producing two identical daughter cells.

Result of Mitosis

• 2 daughter cells

• Diploid (2n)

• Genetically identical

Example in humans:

• Parent cell = 46 chromosomes

• Daughter cells = 46 chromosomes each

PMAT (Stages of Mitosis)

1. Prophase

• Chromosomes condense and become visible

• Nuclear membrane breaks down

• Spindle fibers form

2. Metaphase

• Chromosomes line up in the middle of the cell

• Spindle fibers attach to chromosomes

3. Anaphase

• Sister chromatids separate

• Chromatids move to opposite poles

4. Telophase

• Nuclear membrane reforms

• Chromosomes uncoil

• Two nuclei are formed

After telophase, cytokinesis happens.

CYTOKINESIS

Cytokinesis is the division of the cytoplasm, forming two separate cells.

MEIOSIS

Meiosis is the process that produces gametes (sex cells).

Examples:

• Sperm

• Egg cells

Result of Meiosis

• 4 daughter cells

• Haploid (n)

• Genetically different

Example in humans:

• Parent cell = 46 chromosomes

• Gametes = 23 chromosomes

MEIOSIS I

Called Reduction Division

Key Events:

• Homologous chromosomes pair

• Crossing over occurs

• Chromosomes separate

Result:

• 2 haploid cells

MEIOSIS II

Similar to mitosis

Key Event:

• Sister chromatids separate

Result:

• 4 haploid daughter cells

IMPORTANT TERMS

Chromosome
Structure that contains DNA.

Sister Chromatids
Identical copies of a chromosome.

Homologous Chromosomes
Pair of chromosomes with the same genes.

Diploid (2n)
Cell with two sets of chromosomes.

Haploid (n)
Cell with one set of chromosomes.

MITOSIS vs MEIOSIS

✅ Quick Memory Tips

PMAT order:
P – Prophase
M – Metaphase
A – Anaphase
T – Telophase

Interphase order:
G1 → S → G2