The Cell Cycle and Interphase

How do Multicellular organisms grow?

Grow by cell division, which is tightly regulated by the cell cycle.

Cell Cycle

A repeating sequence of growth and division consisting of four main stages: G1, S, G2, and M Phases.

G1 Phase (Gap 1)

Cell grows, performs normal functions, and prepares for DNA replication.

S Phase (Synthesis)

DNA replication occurs, producing two identical copies.

G2 Phase (Gap 2)

Cell prepares for division by making proteins and organelles.

M Phase (Mitotic Phase)

Active division occurs, consisting of mitosis and cytokinesis.

Interphase

The phase where cells spend most of their lifespan, including G1, S, and G2 phases.

G0 Phase

A non-dividing state where cells perform normal functions indefinitely.

Mitosis

The division of the nucleus during the M phase of the cell cycle.

Cytokinesis

The division of the cytoplasm, forming two identical daughter cells.

Regulatory proteins

Control the cell cycle to ensure accurate progression.

G1 Checkpoint

Determines if the cell is ready to proceed to S phase.

S Checkpoint

Ensures proper DNA replication.

M Checkpoint

Verifies that chromosomes are correctly aligned before division.

Apoptosis

Programmed cell death that may occur if errors are detected in the cell cycle.

Cancer

Occurs when cell cycle regulation fails, leading to uncontrolled cell division.

Carcinogens

Substances that damage DNA and increase mutation rates.

Checkpoint regulatory genes

Mutations in these can lead to the failure of proper cell cycle regulation.