Monday November th 14 Miss Brawley Do Now

Monday, November th 14 Miss Brawley

Do Now: 1. What do we call a critical control point where stop and go signals can regulate the cycle? 2. What macromolecule checks the cycle at checkpoints? 3. The cell division mechanism in most animal cells is in the _____ position (on or off? ) When you are done: • Complete the Chapter Mystery questions on page 278 and 284. (do this in your notebook on your Chapter Mystery Page)

Interphase is divided into three phases: � G 1 (gap 1) phase: the cell grows and synthesizes proteins � S (synthesis) phase: chromosomes replicate and divide to form identical sister chromatids � G 2 (gap 2) phase: cells continue to grow and produce the proteins necessary for cell division

Metaphase- What do you see? Chromosomes line up at the center of the cell. centrioles chromatid centromere chromosome Spindle fibers connect the centromere of each sister chromatid to the poles of the cell.

Metaphase �Chromosome chromatids composed of two sister

Anaphase- what do you see? Chromosomes move toward opposite poles. • Sister chromatids separate individual chromosomes

Telophase- what do you see? The cell begins to divide into daughter cells. Chromosomes uncoil nuclear envelopes re-forming**** Spindle fibers break down and dissolve

Cytokinesis- what do you see? In animal cells, the cell membrane pinches in the center to form two daughter cells.

Plant Cell Telophase/Cytokinesis �In plant cells a structure known as a cell plate forms midway between the divided nuclei, which gradually develops into a separating membrane. �The cell wall forms in the cell plate.

Knowing When to Stop � Suppose you had a paper cut on your finger. Although the cut may have bled and stung a little, after a few days, the cut may have completely healed. � Working with a partner, answer the following questions: 1. How do you think the body repairs an injury, such as a cut on a finger? 2. How long do you think this repair process continues? 3. What do you think causes the cells to stop the repair process?

Cell Division and Repair

Healing a Bone new bone cells • Cells at the edge of an injury are stimulated to divide rapidly. • As an injury heals, the rate of cell division slows.

What’s stopping you? �A person recovering from a bone break or a wound relies on the cell cycle to make new cells to repair damaged tissues. � In the human body, many cell types do not continue dividing. • For example, most muscle and nerve cells do not continue dividing once they have developed. � Other cell types, such as skin, bone marrow, and cells lining the digestive system, grow and divide rapidly and regularly.

The Discovery of Cyclins • Scientists found a protein in a cell undergoing mitosis. • They injected the protein into a non-dividing cell. • A mitotic spindle started to form. • Cyclins: proteins that regulate the cell cycle

Controlling the Cell Cycle �The cell cycle is driven by a chemical control system that both triggers and coordinates key events in the cell cycle. �The cell cycle control system is regulated at certain checkpoints. • Proteins regulate the progress of cell division at certain checkpoints

Checkpoints �A checkpoint in the cell cycle is a critical control point where stop and go signals can regulate the cycle. �The cell division mechanism in most animal cells is in the “off” position when there is no stimulus present. • Specific stimuli are required to start the processes.

Regulatory Proteins Internal regulators: • respond to events inside the cell • let cell cycle proceed only when certain steps have already happened External regulators: • respond to events outside the cell • direct cells to speed up or slow down the cell cycle • growth factors: wound healing and embryonic development

Other types of control over cell division: �Cells respond when they are too closely packed and cell division is turned off. �Cells respond when they are not in contact with a surface and cell division is turned on.

Apoptosis • A process of programmed cell death • Important role in structuring tissues during growth and development • Cell undergoes a series of controlled steps for selfdestruction.

Car Assembly

Rogue

When Cells Go Rogue

Cells Gone Rogue �Special Agent Training Camp (cell cycle) produces new agents �But what happens when Training Camp becomes a breeding ground for Rogue Agents? !?

Cells Gone Rogue �Cancer • • Webquest: Skin- Abigail and Kelvon Bone- Timothy and Saterrence Brain- Tywuan and Tori and Ariel Lung- Amber and Shania Breast- Kayce and Kiana Pancreatic- Tina and Damitria Prostate- I’dae and Daquan Leukemia- Grayson and Ja’Tashjah

Cells Gone Rogue �Cancer • • Webquest: Skin- Matilyn and Tierra Bone- Richard and Devon Brain- Clayton and Kayla Lung- Al’Tayjaha, Kaylee and Connor Colon- Elizabeth and Heather Breast- Adriene, Elise and Kristopher Prostate- Brandon and Ace Leukemia- Jade, Byonka and Ally

Cancer: Uncontrolled Cell Growth • Cancer cells don’t respond to normal regulatory signals. • Cell cycle is disrupted. • Cells grow and divide uncontrollably. tumor blood vessel

Cancer Formation: A Closer Look 1. A cell begins to divide abnormally. 2. Cells produce a tumor and start to displace normal cells and tissues. 3. Cancer cells move to other parts of the body.

What Causes Cancer? In all cancers, control over broken down. the cell cycle has Cancer results from a defect in genes that control cell growth and division.

Treatments for Cancer • Surgery to remove localized tumor • Radiation to destroy cancer cell DNA • Chemotherapy to kill cancer cells or slow their growth

Cancer make me lose control � � � � � If control of the cell cycle is lost, the result may be uncontrolled cell division. Cancer cells are an example of cells that do not heed the normal signals which shut down the cell division process; they continue to divide when they are very densely packed and/or if the protein(s) that regulate cell division are not functioning properly due to a mutation. • Cancer begins when a single cell is transformed into a cancer cell, one that does not heed the regulation mechanism. • Normally the body’s immune system will recognize that the cell is damaged and destroy it, but if it evades destruction, it will continue to divide by mitosis and each daughter cell will be a cancer cell. • A mass of these cells that invades and impairs the functions of one or more organs is called a malignant tumor. • A benign tumor is a mass of abnormal cells that remains at the original site. • Cancer cells may also separate from the original tumor, enter the blood and lymph vessels of the circulatory system, and invade other parts of the body, where they grow to form new tumors.

Revisit Workbook Pages 146 -149