The Problem Of Cell Growth
As cells grow they hit two limits: DNA and exchange limits.  As a cell grows, the DNA cannot produce enough to maintain the cell.  Also, as a cell grows, its volume increases faster than its surface area, meaning that it cannot keep up material exchange to the size of the cell.  Thus, to solve these growth problems, the cell divides.

Cell communication - Paracrine signal vs. Endocrine signal
Cell signals can be local signal (paracrine signal) which is communicated through cell-cell contacts, or endocrine signal which is mostly hormones secreted by glands and transported via blood.

Cell Cycle
Proliferating cells undergo cell cycle which is composed of G1, S, G2 and M phases.  Resting cells are in G0.  Cell cycle is controlled by cyclins and CDKs, when circumstances are not right, cell cycle checkpoints can be activated to restrain cell cycle. 

Mitosis
Mitosis is cell division, with an exact replication of the cell's DNA into a new clone cell.  Mitosis has four stages: prophase, metaphase, anaphase, and telophase.  All of these steps lead to separation of the duplicated DNA in order to give them to the new cell.  After mitosis, cytokinesis splits the cell membranes and cytoplasm into two new identical cells.

Cell Cycle Control

Cell-cell communication is critical for organism survival and homeostasis.  All cell signals are chemical signals.  Chemical signals are received by signal receptors on cell surface or inside cells.  Three major types of receptors are RTKs, GCPRs and intracellular receptors.  RTKs have intrinsic tyrosine kinase activities which are activated upon signal binding; GCPRs are coupled to G proteins which are activated by signal binding. 

Intracellular receptors can bind to signal molecules and then trans-locate into nucleus for activating gene expression.  RTK and GCPR can activate downstream targets and initiate cascade signal transduction.  Signals can be amplified through transduction, especially through second messengers such as cAMP/cGMP, DAG and IP3, and calcium ions.  Dividing cells undergo cell cycle which includes G1, S, G2 and M phases.  Cell cycle are controlled and checked at certain points to ensure proper DNA inheritance. 

• Pictorial description of cell-cell contacts.
• Easy to understand classification of receptors and how they work
• Detailed analysis of second messengers.
• Diagram of cell cycle

The Problem of Cell Growth

• DNA Limits
• Exchange Limits
• The Solution

The Cell Cycle

• Overview
• G1/S/G2/M

Mitosis

• Definition
• Overvie
• Prophase/Metaphase/Anaphase/Telophase
• Cytokinesis

Cell Cycle Control

• Cycle Checkpoints
• Cyclins and Kinases
• Cancer