NameMy pts Pts Poss.Tot “My Pts” TPPGrade 12 Cell Test Homework for week of Dec Mon. Read Ch.3 Tues. Work Day Weds. $3 Pizza Per. 7 Mitosis Flipbooks Due Thurs. Beginning of class Thurs. None Friday Happy Holidays!

Homework for week of Dec Mon. 8.2 Unit Guide Tues. Mitosis Flipbooks Due Thurs. Beginning of class Weds. $3 Pizza due Semester Final Today! Thurs. None Friday Happy Holidays!

NameMy pts Pts Poss.Tot “My Pts” TPPGrade 12Ch 7 Unit Guide 20 13Current Event 40 14Cell Test Sem Midterm Mitosis Flipbook 40570

Today’s Goal: Explore how and why cells divide.

Cells divide. This makes cells small. Why do cells divide? Why must cells be small?

7 7 Asexual Reproduction Mitosis Mitosis is the process in which the nucleus divides to form two new nuclei. How does mitosis differ in plants and animals?

How do little elephants grow up to be BIG elephants?

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

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

1. Growth- increase in size of the organism (by dividing cells, not by increasing the size of the cells) 2. Repair – needed because of worn out or injured cells (your skin cells are replaced every 28 days; your stomach every 7) 3. Reproduction (2 types)  Asexual – one parent. Offspring identical to parent - mitosis  Sexual – combination of genetic material from two parents - meiosis

Animated Mitosis Cycle Interphase Prophase Metaphase Anaphase Telophase & Cytokinesis

Chromosomes are copied (# 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 CELL MEMBRANE Nucleus Cytoplasm Centromere

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. Centrioles Sister chromatids Spindle fibers

Animal Cell Plant Cell Photographs from: Spindle fibers Centrioles

Chromatids (or pairs of chromosomes) attach to the spindle fibers. Centrioles Spindle fibers

Animal Cell Plant Cell Photographs from:

Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Centrioles Spindle fibers

Animal Cell Plant Cell Photographs from:

Two new nuclei form. Chromosomes appear as chromatin (threads rather than rods). Mitosis ends. Nuclei Chromatin

Animal Cell Plant Cell Photographs from:

Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

I I nterphase P P rophase M M etaphase A A naphase T T elophase C C ytokinesis IPMATC I Pray M ore At T he Church

28

29 - Cell Division 29