Eukaryotic Cell Cycle: Interphase, DNA and Chromosomes

• The eukaryotic cell cycle consists of sub-phases of mitosis and cytokinesis in plant and animal cells.
• The cell cycle is how a newly formed cell matures and replicates.
• The three main stages of the cell cycle include interphase, mitosis, and cytokinesis.

Interphase

• Interphase involves cell growth and duplication of chromosomes.
• Cells spend most of their lives in interphase.
• Interphase is separated into three phases: G1, S, and G2.
• The cell grows and increases in volume during Growth 1 (G1).
• Organelles are replicated and prepares for DNA replication during G1.
• The cell replicates its DNA/chromosomes during Synthesis (S).
• Cell growth occurs and the cell prepares for mitosis during Growth 2 (G2).

DNA and Chromosomes

• A chromosome consists of DNA tightly wrapped around proteins
• Chromosomes carry the genetic information (genes) of a cell.
• Human somatic cells are diploid (2n), containing two copies of every chromosome from each parent.
• Human cells have 23 pairs or 46 total chromosomes.
• A duplicated chromosome consists of two "sister chromatids".
• Sister chromatids separate during mitosis.

Mitosis and Cytokinesis

• Mitosis comes second in the cell cycle.
• Mitosis results in exact and equal amounts of nuclear DNA in each daughter cell.
• Daughter cells are genetically identical.
• Mitosis has several stages: Prophase, Metaphase, Anaphase, and Telophase (P → M → A → T).
• Cytokinesis follows mitosis.

Regulation

• The cell cycle has checkpoints to check for errors for the next stages.
• The cell cycle halts for repairs if a cell is damaged or not ready.
• Apoptosis, or programmed cell death, may occur if the damage cannot be repaired.
• G1, G2, and M checkpoints exist.
• Uncontrolled cell division from malfunctions can result in tumor or cancer formation.