MITOSIS NOTES Mitosis Brain Pop TWILIGHT MITOSIS CLIP

The Cell Cycle Review (not in notes) www. wiley. com/college/test/0471787159/biology_basics/animations/mitosis. swf Reminder, the cell cycle is a series of events that cells go through as they grow and divide. During the cell cycle, the following happens: • Cell grows (interphase) • Cell prepares for division (interphase) • Cell divides to form 2 daughter cells (each of which further divide) (cell division)

Events of Interphase • Interphase (not in notes) – G 1 phase – Cell grows – - S phase PLANT CELL IN INTERPHASE ANIMAL CELL IN INTERPHASE – Replication of chromosomes/DNA synthesized – G 2 phase • Cell prepares to divide

Why Do Cells Divide? • The larger a cell becomes, the more demands the cell places of its DNA. • The cell also has more trouble moving enough nutrients and wastes across the cell membrane.

Division of the Cell § § § Before it becomes too large, a growing cell divides forming two “daughter cells. ” The process by which a cell divides into new daughter cells is called cell division. Before cell division occurs, the cell replicates, or copies, all of its DNA. Thus, each daughter cell gets one complete set of genetic information.

Cell Division- M Phase • Cell division is complex and occurs in 2 main stages: – Mitosis-division of cell nucleus – Cytokinesis- division of cytoplasm Cytokinesis is part of cell division but not technically a phase of mitosis.

Our Genetic Information • Genetic information is carried by chromosomes. – During the S Phase of the Cell Cycle, each chromosome is replicated, or copied forming two identical sister “chromatids, ” which will be separated from each other when the cell divides.

• -Chromosomes are organized sections of DNA that contain genetic information • - Sister Chromatids are replicated chromosomes that will separate during mitosis so that each cell gets one

Figure 10– 5 Mitosis and Cytokinesis Section 10 -2 Spindle forming Centrioles Nuclear envelope Chromatin Interphase Centromere Chromosomes (paired chromatids) Prophase Cytokinesis Mitosis Clip 1 (1: 30) Spindle Centriole Telophase Nuclear envelope reforming Centriole Individual chromosomes Anaphase Mitosis Clip 2 (1: 22) Metaphase

Mitosis and Cytokinesis (M Phase) • When the events of the G 2 phase are completed, the cell is ready to enter the M phase and begin cell division. • The events of mitosis are divided into four phases: • • 1) Prophase 2) Metaphase 3) Anaphase 4) Telophase

Prophase • 1 st phase of mitosis where: –Centrioles take their place at opposite sides of the cell –Spindle fibers form –Chromatin coils to form chromosomes –Nuclear envelope breaks down

Metaphase 2 nd phase of mitosis where: The chromosomes line up across the center (middle) of the cell. • Each chromosome is connected to a spindle fiber at its centromere.

Anaphase 3 rd Phase of Mitosis where: Sister chromatids separate into individual chromosomes and are moved apart towards the poles of the cell

Telophase 4 th phase of Mitosis where: • The chromosomes gather at opposite ends of the cell and lose their distinct shapes. • Two new nuclear envelopes (membranes) will form.

Cytokinesis • This follows mitosis and is not officially a stage of mitosis. • This is when the cytoplasm pinches in half. • Each resulting daughter cell has an identical set of chromosomes and has the same number of chromosomes as the parent cell. AMOEBA SISTERS AWESOME MITOSIS SUMMARY

How will I ever remember the phases of the cell cycle? • I • P • M • A • T • C INTERPHASE PROPHASE METAPHASE ANAPHASE TELOPHASE CYTOKINESIS

This is how you can remember the phases: • I • Passed • My • Algebra • Test • Commended Click here for Mr Martin’s Mitosis Hand Signals Clip Another way of remembering just the four phases of mitosis: PLEASE MAKE ANOTHER TOUCHDOWN and use the hand signals like a cheer!

Disruptions • Disruptions in mitosis can lead to diseases such as cancer. • Cells contain internal and external regulators. Internal regulators allow the cell cycle to proceed only when certain processes have occurred (ex. all chromosomes have been replicated) • Cancer is an uncontrolled synthesis of cells. If a mutation occurs in the genes that control the cell cycle, then mitosis could occur before the cell has gone through the all stages of interphase or even if the cell has been damaged.

Types of Cancer Cells A cluster of cancer cells forms a tumor. There are two types of tumors. In a benign tumor, the cancer cells remain clustered together. This means the tumor remains relatively harmless and can be treated just by removing it. If a tumor is malignant, some of the cancer cells can break away, or metastasize, from the tumor. They can be carried in the bloostream and affect other parts of the body. These are much harder to get rid of and treatment will often involve chemotherapy or radiation.

Cancer cells are harmful because they do not perform the specialized functions for that area of the body. Cancer cells or a tumor in the lung do not actually help with gas exchange and instead take up room and make the organ less effective. Some substances are known to promote the development of cancerous cells. These are called carcinogens and examples include tobacco smoke and air pollutants. THE AMOEBA SISTERS EXPLAIN THE CELL CYCLE AND CANCER