Ch.10-3 Regulating the Cell Cycle

POINT > Identify 3 reasons cells divide POINT > Describe the role of cyclins in cell division POINT > Identify other factors that affect cell division POINT > Define apoptosis POINT > Discuss causes and treatments of cancer

1. Growth & Development

2. Repair & Healing

1. Growth & Development 2. Repair & Healing 3. Reproduction (in asexual organisms)

Cyclins are a family of proteins that regulate the timing of the cell cycle Cyclins “tell” the cell when to:  Replicate chromosomes  Divide  Enter another phase of the cell cycle

Cyclin production during interphase signals cell to enter mitosis Cyclin destruction during mitosis signals cell to stop dividing and enter interphase Directions (5 min total) Open textbook to p.288 Answer questions 1-3 with partner

When during the cell cycle does cyclin production occur? Cyclin production causes the cell to a) enter interphase b) prepare for mitosis c) end mitosis d) increase active transport

When during the cell cycle does cyclin destruction occur? Cyclin destruction causes the cell to a) enter interphase b) prepare for mitosis c) undergo cytokinesis d) increase active transport

Many other factors help regulate the cell cycle: Internal regulators respond to events inside the cell (attachment of spindle fibers, DNA replication, etc) These internal regulators allow the cell cycle to proceed only when certain events (like DNA replication) have been completed

External regulators respond to events outside the cell (growth factors, cell surface proteins, etc) These regulators can direct cells to speed up or slow down the cell cycle

What is one event an internal cell cycle regulator might detect or respond to? An example of an external cell cycle regulator would be a) DNA polymerase b) Cyclins c) Spindle fiber proteins d) Growth factors

Apoptosis is “programmed cell death” through a series of controlled steps Cells commit “suicide” as part of normal growth and development

Apoptosis is essential to shaping structures of tissues and organs in plants and animals Cells with mutations or problems with DNA replication also undergo apoptosis Mouse Embryo Paw

Apoptosis is important for a) ensuring mitosis occurs normally b) proper development of organs and body structures c) preventing mutated cells from growing d) a-c e) b-c f) a and c

Cancer is a group of disorders characterized by uncontrolled cell division Uncontrolled cell division creates tumors (masses of cancer cells) Benign tumors do not spread and are usually treatable Malignant tumors do spread, invading and damaging other tissues Melanoma

Cancer is usually caused by mutations to a cell’s regulatory genes (causes of mutations include tobacco, radiation, natural mutations, and viral infections) As a result, control over the cell cycle breaks down: 1. Cells don’t respond to external growth factors 2. Cells fail to produce internal regulators 3. Mutated cells fail to undergo apoptosis

Cancer is usually treated through: Surgery Radiation Chemotherapy Targeted Therapy: (Newer methods - often use antibodies of immune system proteins to destroy cells) Classic Treatment Options

Read Assess #1-3 page 290 Workbook pages