DO NOW!!! True or False: Single–celled organisms can reproduce by cell division. The only function of cell division is reproduction. In multicellular organisms, cell division can help repair injured areas. Cell division produces two cells that are different from each other. T, F, T, F

Mitosis Unit 2 Lesson 1

Why do cells divide? Different reasons: Asexual reproduction Growth in a multicellular organism Repair of cells 3

Asexual Reproduction Single celled organism - parent divides to produce two identical offspring. https://www.youtube.com/watch?v=vnlk vquWXS8

Growth in multicellular organisms All living things grow Body grows - cells in your body produce new cells through cellular division

Cell Division for Repair Cut your hand or break a bone - damaged cells are replaced by new cells (form during cell division) Some organisms - cell division repairs body parts that have been removed.

Cell Division for Repair

Genetic Material Form: Double Helix Parts: Adenine Thymine Cytosine DNA = deoxyribonucleic acid. Eukaryotic cells - found in the nucleus. Contains - information that determines the traits living thing inherits from parents and needs to live. Form: Double Helix Parts: Adenine Thymine Cytosine Guanine 9

Chromatin Most of Cells life - DNA exists as chromatin. When the DNA Duplicates, you have 46 duplicated chromosome. They are considered one duplicated chromosome. When they separate during anaphase then one duplicated chromosome becomes two chromosomes. 10

Before Mitosis Before cell division – DNA (chromatin) - duplicates. =

Chromosome (Condensed DNA) As Mitosis begins - duplicated chromatin (DNA)  Sister chromatids  sister chromatids condense = Duplicated Chromosome

Chromosomes under the Microscope

Different levels of DNA condensation: (1) Single DNA strand Different levels of DNA condensation: (1) Single DNA strand. (2) Chromatin strand (3) Chromatin during interphase with centromere (4) Chromatin Duplicated  Sister Chromatids (5) Sister Chromatids Condense = Duplicated Chromosome

Chromosome DNA Chromatin Chromatin  Chromatin Duplicates = Sister Chromatids  Sister Chromatids Condense = Duplicated Chromosome Chromosome DNA Chromatin 15

HW Turn to page 92 and 93 and Complete Questions 5 to 7

DO NOW!!! Highlight Definition for: Interphase Mitosis Cytokinesis On pages 94 and 95!!! Then do question #10.

Stages of the cell cycle Life cycle of a eukaryotic cell - cell cycle - divided into three stages: Interphase Mitosis Cytokinesis. 18

Interphase Interphase - stage of cell cycle when cell is not dividing. Cell spends 90% of its life here Cell engages in normal life activities transporting materials getting rid of waste 19

Interphase Before Cell Division Cell grows - 2x its size -producing more organelles and cytoplasm. DNA is duplicated Changes prepare cell for division.

Mitosis – Cell Division Eukaryotic cells - part of cell cycle where nucleus divides. 4 phases: Prophase Metaphase Anaphase Telophase Prokaryotes – No nucleus = No Mitosis 21

Mitosis (Cell Division) Creates: 2 identical nucleuses 2 identical sets of chromosomes in in each nucleus During – Duplicated chromatin  sister chromatids condense  Duplicated chromosomes

Cytokinesis Cytokinesis - division cytoplasm. Starts - last step of mitosis (telophase) Forms – 2 identical cells 23

Cytokinesis in Animal Cells Animal cells - cell membrane pinches inward between 2 nucleuses. Pinches all the way - forming two complete cells

Cytokinesis in Plant Cells Cell wall – No Pinch – Cell Plate forms between 2 nucleuses and separates cell into 2 identical cells

HW Read page 96 and 97 then fill out the table on page 97, #13.

DO NOW!!! http://www.sciencekids.co.nz/videos/biolo gy/mitosis.html Mitosis video : Lets watch what is really happening!

The 4 Phases of Mitosis Prophase Metaphase Anaphase Telophase By the end of the four phases, the cell will have two identical nuclei. 30

Prophase Spindle fibers attach to the centromeres of every chromosome. Duplicated Chromatin = Sister Chromatids  Sister Chromatids Condense = Duplicated Chromosomes Each Chromosome = two chromatids held together by a centromere. Nuclear membrane – breaks down Spindle fibers attach to the centromeres of every chromosome. 31

Metaphase Chromosomes line up in the middle of the cell. Centromeres of chromosomes - same distance from each side of the cell. 32

Anaphase Duplicated Chromatids of each chromosome are pulled apart to opposite sides of the cell. Note on it pinching in during this picture and ask students about it. 33

Telophase + Cytokinesis New nuclear membrane forms around each group of chromosomes Chromosomes - become less condensed. Cytokinesis begins 34

Cytokinesis After mitosis - cytokinesis forms two new identical cells Cycle starts again for each cell 35

Activity + HW Listen to the Mitosis Song to Learn more about this topic: https://www.youtube.com/watch?v=IlV9hExX ZnM https://www.youtube.com/watch?v=ZEwddr9h o-4 In Class Complete the Visual summary on page 98 and the Unit 2 Lesson 1 Review on Page 99

Class Activity Create a Picture Poster Showing: . What happens to genetic material (DNA) in a cell before cell division (Mitosis) Use these Labels – Chromatin  chromatin duplicates  sister chromatids  sister chromatids condense = Duplicated chromosome What happens to that genetic material (DNA) and the cell once cell division occurs (Mitosis) Use Mitosis labels – Interphase, Prophase, Anaphase, Telophase, & Cytokinesis – Explain what happens in each stage