Mitosis Compare the advantages of sexual and asexual reproduction in different situations. The student will be able to do the following: Recognize the steps of Mitosis Understand Mitosis is a form of asexual reproduction

How do little elephants grow up to be BIG elephants?

Why do animals shed their skin?

Why do our cuts heal?

Cell Division—Mitosis Cell Division —process by which a cell divides into 2 IDENTICAL daughter cells Why do cells need to divide? Growth Repair of damaged tissue Replacement

Understanding the Basics The original cell is called the parent cell 2 new cells are called daughter cells Each daughter cell is exactly like the parent cell Same number of chromosomes 2 Daughter Cells Parent cell

What’s in a name? Where is DNA found?? Long and thread-like DNA in a non-dividing cell is called chromatin Doubled, coiled, short DNA in a dividing cell is called chromosome Chromatin Chromosome Duplicating

Chromosome Structure Chromosome parts: chromatid and centromere A chromatid is one copy of a duplicated chromosome A centromere is the place where the chromatids join

Numbers are Important! All somatic (body) cells in an organism have the same kind and number of chromosomes Examples: Human = 46 chromosomes Human skin cell = 46 chromosomes Human heart cell = 46 chromosomes Human muscle cell = 46 chromosomes Fruit fly = 8 chromosomes Fruit fly skin cell = 8 chromosomes Fruit fly heart cell = 8 chromosomes Fruit fly muscle cell = 8 chromosomes

Mitosis Cell Cycle Interphase Prophase Metaphase Anaphase Telophase and Cytokinesis

Interphase Growth 1 (G1) Phase Synthesis (S) Phase Three phases: G1, S, and G2 Growth 1 (G1) Phase Normal state of the cell Carries out daily activities Synthesis (S) Phase Preps for another cell division Centrioles duplicate (for 2 pairs) DNA is replicated DNA unwinds into chromatin Growth 2 (G2) Phase Cell prepares for division of nucleus Cell does final check before start ingMitosis

Prophase Prepares cell for Mitotic division Chromotin condense (coils) to chromosomes Each half of chromosome is called a sister chromatid Sister chromatids are connected by a centromere Centrioles move to correct poles Nuclear envelope dissolves Spindle Fibers

Metaphase Sister chromatids line up in the middle of cell Centrioles send out spindle fibers to attach to centromere

Anaphase Separation begins Spindle fibers shorten Sister chromatids are pulled apart and go to separate sides of cell

Telophase Telophase The sister chromatid halves begin to decondense New cell nucular membrane forms

Cytokinesis Division of the cytoplasm to from 2 new cells Creates 2 separate daughter cells

Summary: Cell Cycle Interphase Mitosis Cytokinesis When cells become old or damaged, they die and are replaced with new cells

How to Remember The Phases I-P-M-A-T-C I Playfully Meow At The Cat

Cell Division Control DNA controls all cell activities including cell division Some cells lose their ability to control their rate of cell division – the DNA of these cells has become damaged or changed (mutated) These super-dividing cells form masses called tumors

Benign tumors are not cancerous – these cells do not spread to other parts of the body Malignant tumors are cancerous – these cells break loose and can invade and destroy healthy tissue in other parts of the body (called metastasis)

Cancer is not just one disease, but many diseases – over 100 different types of cancers

Many organisms, especially unicellular organisms, reproduce by means of cell division – called asexual reproduction – Ex: bacteria