1 1 Asexual Reproduction Mitosis 3 Questions will be asked in 3 minutes. Write a brief answer for each one. Be prepared to share your answer.

Mitosis is the process in which the nucleus divides to form two new nuclei. How does mitosis differ in plants and animals?

WHY DO CELLS DIVIDE? Give me 2 reasons.

HOW will YOU remember IPMAT?

How do little elephants grow up to be BIG elephants?

The process of asexual reproduction begins after a sperm fertilizes an egg.

You started as a cell smaller than a period at the end of a sentence…

How did you get from there to here?

Skin cancer - the abnormal growth of skin cells - most often develops on skin exposed to the sun. Cells that reproduce by asexual reproduction reproduce constantly.

Use your book and define the following terms in your notes. You have 5 minutes. 1) Page 244CHROMOSOME (it is not in bold, so read carefully) CHROMATID 2)Draw a chromatid. 3) Page 245 CENTROMERE 4) Page 247 SPINDLE

 Strands of DNA  Each human has 23 pair (diploid or 2n)  One from your mother  One from your father

One from Mom One from Dad Sister chromatids DNA molecule with attached proteins

Chromosome number Every organism has its own specific number of chromosomes Examples: Human = 46 chromosomes or 23 pairs Dog = 78 chromosomes or 39 pairs Goldfish = 94 chromosomes or 47 pairs Lettuce = 18 chromosomes or 9 pairs

1. Interphase 2. MitosisMitosis a. G1 b. S c. G2 a.Nuclear division b. Cytokinesis 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase From the Virtual Cell Biology Classroom on ScienceProfOnline.comVirtual Cell Biology ClassroomScienceProfOnline.com

Control of the Cell Cycle

 Prior & After Mitosis  G1 period  90% of cell life spent here  Cell goes about it’s business  S period  DNA is duplicated  G2 period  Cell prepares to divide  Cannot see DNA- uncoiled as chromatin

Animated Mitosis Cycle Interphase Prophase Metaphase Anaphase Telophase & Cytokinesis

Chromosomes are duplicated (# doubles) Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy(sister chromosome) change to sister chromatids at end of this phase Cells are usually in interphase CELL MEMBRANE Nucleus Cytoplasm

Animal Cell Plant Cell Photographs from:

Mitosis begins (cell begins to divide) Centrioles (or poles) appear and begin to move to opposite end of the cell. Spindle fibers form between the poles. Chromosomes coil up and become visible, thicker, and shorter Nuclear envelope disappears Centrioles Spindle fibers

Animal Cell Plant Cell Photographs from: Spindle fibers Centrioles

Metaphase = Middle Chromosomes attach to the spindle fibers. Chromosomes move to the middle of the cell.

Animal Cell Plant Cell Photographs from: Metaphase 2 nd step in Mitosis

Chromosomes separate and begin to move to opposite ends of the cell. Spindle fibers pull chromosomes to opposite poles

Animal Cell Plant Cell Photographs from:

Chromosomes uncoil and appear as threads rather than rods. Nuclear membrane reforms around chromosomes. Two new nuclei form. Spindle fibers disappear Mitosis ends.

Animal Cell Plant Cell Photographs from:

Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes. Cytoplasm divides. After mitosis and cytokinesis, the cell returns to Interphase to continue to grow and perform regular cell activities

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

I Interphase P Prophase M Metaphase A Anaphase T Telophase C Cytokinesis IPMATC I Pray M ore At T he Church

 Prophase:  Chromosomes condense  Nuclear envelope disappears  centrosomes move to opposite sides of the cell  Spindle forms and attaches to centromeres on the chromosomes  Metaphase  Chromosomes lined up on equator of spindle  centrosomes at opposite ends of cell  Anaphase  Centromeres divide: each 2-chromatid chromosome becomes two 1- chromatid chromosomes  Chromosomes pulled to opposite poles by the spindle  Telophase  Chromosomes de-condense  Nuclear envelope reappears  Cytokinesis: the cytoplasm is divided into 2 cells

Phase Chromosome Appearance & Location Important Events Interphase Prophase Metaphase Anaphase Telophase Cytokinesis

Phase Chromosome Appearance & Location Important Events Interphase Prophase Metaphase Anaphase Telophase Cytokinesis DNA replication, cell grows and replicates organelles Nuclear envelope disappears, spindle fibers form DNA copies itself; chromatin Chromosomes coil up Chromosomes line up in the middle Spindle fibers connect to chromosomes Chromosome copies divide and move apart Spindle fibers pull chromosome copies apart to opposite poles Chromosomes uncoil back into chromatin Nuclear envelopes reform, 2 new nuclei are formed, spindle fibers disappear Division of the rest of the cell: cytoplasm and organelles Chromatin

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