Cell Division & Mitosis Yay Getting closer and closer to the FUN stuff!!!

Cell Division What is cell division?What is cell division? –Process where a cell splits into 2 individual daughter cells Why do we need cell division?Why do we need cell division? New cells are produced for growth and to replace damaged or old cells New cells are produced for growth and to replace damaged or old cells There are 2 major typesThere are 2 major types –Mitosis- division of the NUCLEUS –Cytokinesis- division of the CYTOPLASM

3 DNA Replication Replication = COPY Replication = COPY DNA must be copied or replicated before cell division DNA must be copied or replicated before cell division Each new cell will then have an identical copy of the DNA Each new cell will then have an identical copy of the DNA Original DNA strand Two new, identical DNA strands copyright cmassengale

4 Identical Daughter Cells Parent Cell Two identical daughter cells copyright cmassengale

Chromosomes These are super important little friendsThese are super important little friends Here are some defining characteristicsHere are some defining characteristics –Made of tightly coiled DNA –Found in the NUCLEUS –The number depends on the organism they live in… usually –Humans have 46 chromosomes in pairs (23 pairs)

6 Chromosomes in Dividing Cells chromosomes are made of 2 chromatids that are held together by the centromere Called Sister Chromatids copyright cmassengale

7 Types of Cell Reproduction Asexual reproduction -1 cell dividing to make 2 new, identical daughter cells Asexual reproduction -1 cell dividing to make 2 new, identical daughter cells ex. Mitosis & Binary Fission Sexual reproduction- two cells (egg & sperm) making new cell (zygote) that is NOT identical to the original ex. Meiosis copyright cmassengale

8 Cell Division in Prokaryotes Prokaryotes (bacteria) divide into 2 identical cells through binary fission Prokaryotes (bacteria) divide into 2 identical cells through binary fission Parent cell 2 identical daughter cells Chromosome replicates Cell splits copyright cmassengale

The cell cycle Cell Cycle- events cells go through as they grow and divide The cell cycle consists of five phases:The cell cycle consists of five phases: –G 1 (Primary Growth Phase) Cell increases in sizeCell increases in size –S Phase (Synthesis) Chromosomes are replicatedChromosomes are replicated –G 2 (Second Growth Phase) Organelles are producedOrganelles are produced –M Phase MITOSISMITOSIS –Cytokinesis These three phases are known as Interphase

Sketch me!!!

Interphase Not technically a part of mitosisNot technically a part of mitosis Includes G1, S, and G2Includes G1, S, and G2 Organelles double in number to prepare for divisionOrganelles double in number to prepare for division Mitosis- Division of the nucleus These are the phasesThese are the phases – Prophase –Metaphase –Anaphase –Telophase

12 Four Mitotic Stages Prophase Prophase Metaphase Metaphase Anaphase Anaphase Telophase Telophase copyright cmassengale

Prophase Spindle fibers form Centrioles move to opposite poles Chromosomes become visible

Metaphase Chromosomes line up at the EQUATOR

Anaphase Centromeres divide Chromatids separate and move to the opposite poles

Telophase Nuclear membrane forms around each of the chromosomes Chromosomes unwind Cytokinesis begins

Cytokinesis Cytoplasm divides and one cell becomes two individual cells.

The difference ANIMALSPLANTS Extra credit! Cleavage Furrow is formed Extra Credit Cell Plate is formed

19 Cytokinesis Cleavage furrow in animal cell Cell plate in plant cell copyright cmassengale

20 Mitosis in Onion Root Tips Do you see any stages of mitosis? copyright cmassengale

21 Karyotype A picture of the chromosomes from a human cell arranged in pairs by size A picture of the chromosomes from a human cell arranged in pairs by size Remember this! We’ll make one of these after Christmas! copyright cmassengale