Mitosis, Significance to unicellular and multicellular organisms, Chromosomes

Significance of cell reproduction to multicellular & unicellular organisms 1. Unicellular: reproduce by cell division. Also called binary fission.

2. Multicellular- processes of growth and repair upon cell division, also the production of sex cells.

Describe chromosomes 1. Carriers of genetic material found in nucleus 2. Made up of DNA 3. Information is copied and passed to future generations

4. Usually exist as chromatin a. long, winding strands which condense into chromosomes before dividing 5. Human chromosome number is 46 in body cells, 23 in sex cells

The Cell Cycle 1. The cell cycle is a sequence of growth and division of a cell Made up of 2 distinct stages: A. Interphase: growth period where DNA is copied B. Mitosis: dividing period producing 2 new cells

7 Hours DNA synthesis 3 Hours Growth & final prep 11 Hours Rapid growth, centrioles replicate TA M P Interphase Mitosis-1 hour

Interphase- the first part of the cell cycle 1.Also called the resting stage 2.Cells make ATP 3.The cell repair themselves 4.Make proteins 5.Make new organelles 6.Copying new chromosomes(DNA)

Mitosis Mitosis is the division of the cytoplasm followed by cell division. There are 4 stages of mitosis.

Prophase The following events occur: 1.Chromatin coils to form short rods 2.The 2 copies (chromatids) join to form chromosomes- held together by centromere 3.Nuclear membrane disappears

4. Centrioles move to opposite ends of the cell 5. Spindle forms- helps pull chromosomes apart & are attached to centrioles centrioles

Metaphase 1.Chromosomes attach to spindle fibers 2.Chromosomes line up in the middle of the cell(equator).

Anaphase 1.Centromeres split apart 2.Chromatids pairs split apart and begin to move to opposite ends(poles).

Telophase 1.Chromatids reach opposite poles. 2.Chromatids begin uncoiling to form chromatin again 3.Spindle breaks down 4.Nucleolus and nuclear membrane reappear 5.Plasma membrane begins to pinch in

Division of Cytoplasm-cytokinesis In animals-the cell pinches in along the equator In plants- the cell plate forms down the equator of the cell

Quiz #1 Mitosis

1.The sequence of events of cell growth & division is called __________. a. Mitosis cycleb. cell cyclec. division cycle 2. __________ is when the cell prepares itself by copying DNA, repairing itself & making new organelles. a. Metaphase b. prophase c. interphase d. telophase 3. Name the phase in which chromosomes are lined up at the equator. a. Anaphase b. telophase c. cytokinesis d.metaphase 4.As the cytoplasm divides, what forms in plants down the equator of the cell? a. chromatidsb. chromosomesc. cell plate

5. Identify the correct phase of the cell cycle & mitosis. a. interphase, prophase, metaphase, anaphase, telophase b. prophase, metaphse, interphase, anaphase, telophase c. telophase, metaphase, anaphase, interphase, prophase d. telophase anaphase, metaphase, prophase, interphase