10-2 Cell Division In eukaryotes, cell division occurs in 2 major stages. Mitosis: cell nucleus divides (exact copy made) 2. Cytokinesis: division of the cell cytoplasm. Cyto = cell kinesis = movement cytoplasm cytoskeleton pyrokinesis telekinesis

Chromosomes: How genetic information is passed from one generation to the next. Before cell division, each chromosome is duplicated (copied).

Copyright Pearson Prentice Hall Chromosomes Each chromosome consists of two identical “sister” chromatids. Each pair of chromatids is attached at an area called the centromere. Sister chromatids Photo Credit: © Gunther F. Bahr/AFIP/Stone Centromere Copyright Pearson Prentice Hall

When the cell divides, the chromatids separate. Chromosomes When the cell divides, the chromatids separate. Each new cell gets one chromatid – which becomes a new chromosome for the new cell

Draw and label a chromosome:

Draw and label a chromosome: The “other” Sister Chromatid Sister Chromatid centromere the whole thing is a chromosome chromatin DNA

When can you see chromosomes? Normally the DNA is unraveled as Chromatin …. BUT

During Mitosis you can see the DNA as chromosomes!!!

Mitosis Is divided into four phases: (PMAT) Prophase Metaphase Anaphase Telophase 12

Bellwork: Fri. Oct. 23, 2015 Draw the dividing plant and animal cells and label the dividing features J Plant: forms a “cell plate” Animal: forms a “cleavage furrow”

Copyright Pearson Prentice Hall What is this? Copyright Pearson Prentice Hall

cleavage

Metaphase Interphase Prophase Telophase Anaphase 1 3 2 centrioles Nuclear membrane DNA = chromatin centromere Sister chromatids Spindle fiber Telophase Anaphase 5 4 17

Metaphase Interphase Prophase Telophase Anaphase 1 3 2 centrioles Nuclear membrane DNA = chromatin centromere Sister chromatids Spindle fiber Telophase Anaphase 5 4 18

Cytokinesis in an animal cell

Copyright Pearson Prentice Hall Cytokinesis in Plants In plants, a structure known as the cell plate forms midway between the divided nuclei. Cell plate Cell wall Copyright Pearson Prentice Hall

The Cell Cycle http://www.biologycorner.com/bio1/cellcycle.html Animals - cell pinches inward Plants - a new cell wall forms between the two new cells

Bellwork: Mon. Oct. 26, 2015 Do you know the 4 phases of mitosis? _________ __________ _________ _______ What is the long phase between mitosis? ___________ Prophase Metaphase Anaphase Telophase Interphase

Cell Cycle Notes: Series of events cells go through as they grow and divide. Interphase: period of growth that occurs between cell divisions.

During cell cycle: cell prepares for division grows divides to form 2 daughter cells - each of which begins the cycle again

1st 3 occur during Interphase: Cell Cycle = 4 phases – 1st 3 occur during Interphase: G1 (First Gap Phase) S Phase G2 (Second Gap Phase) M Phase (mitosis)

use your ruler to divide one quarter into fifths

Now label the Phases of the Cell Cycle G1 Phase Now label the Phases of the Cell Cycle S Phase Cytokinesis Telophase G1, S, G2 are Interphase!!! Anaphase Mitosis Metaphase G2 Phase Prophase PMAT !!!

Cell Cycle Cell increases in size & synthesizes new proteins and organelles chromosomes are replicated DNA synthesis takes place During the cell cycle, the cell grows, replicates its DNA, and divides into two daughter cells. DNA synthesis takes place during the S phase. Cell division takes place during the M phase. G1 and G2 are gap phases. Organelles & molecules required for cell division made

Cell Cycle Cell increases in size & synthesizes new proteins and organelles chromosomes are replicated DNA synthesis takes place During the cell cycle, the cell grows, replicates its DNA, and divides into two daughter cells. DNA synthesis takes place during the S phase. Cell division takes place during the M phase. G1 and G2 are gap phases. Organelles & molecules required for cell division made

Why Do Cells Divide? Reproduction Growth Repair Mitosis: nuclear division, number of chromosomes remains the same

Skin cells are always “falling off” of us so skin is constantly going through mitosis to replace the lost skin cells

http://www.youtube.com/watch?v=LSJKXlK3Lx8 Mitosis – Cell Cycle http://www.youtube.com/watch?v=C6hn3sA0ip0 What's the difference between identical and fraternal twins? http://www.youtube.com/watch?v=LSJKXlK3Lx8

But when you look at a cell it may not be so clearly defined Cell getting ready to come out of Interphase and move into early prophase Chromosomes condensing in later prophase Chromosomes “met” up in the middle during metaphase During telophase the cell looks like a “telophone” Sister chromatids being “ripped apart” during anaphase You can see the “cleavage furrow” right before cytokinesis in later telophase Most eukaryotic cells go through a regular cycle of interphase, mitosis and cytokinesis. Mitosis has four phases: Prophase, Metaphase, Anaphase and Telophase. The events shown here are typical of animal cells. But when you look at a cell it may not be so clearly defined

Chromosomes (paired chromatids) Mitosis Section 10-2 Spindle forming Prophase Prophase Chromosomes (paired chromatids) Centromere Most eukaryotic cells go through a regular cycle of interphase, mitosis and cytokinesis. Mitosis has four phases: Prophase, Metaphase, Anaphase and Telophase. The events shown here are typical of animal cells. Click to Continue Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Spindle forming Prophase Prophase is the first and longest phase of mitosis. The centrioles separate and take up positions on opposite sides of the nucleus. Centromere Chromosomes (paired chromatids) Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Spindle forming The centrioles lie in a region called the centrosome. The centrosome helps to organize the spindle, a fanlike microtubule structure that helps separate the chromosomes. Centromere Chromosomes (paired chromatids) Copyright Pearson Prentice Hall

Chromatin condenses into chromosomes. Mitosis Spindle forming Chromatin condenses into chromosomes. The centrioles separate and a spindle begins to form. The nuclear envelope breaks down. Centromere Chromosomes (paired chromatids)

Copyright Pearson Prentice Hall Mitosis Metaphase Centriole Spindle Centriole Metaphase Click to Continue Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Centriole Metaphase The second phase of mitosis is metaphase. The chromosomes line up across the center of the cell. Microtubules connect the centromere of each chromosome to the poles of the spindle. Spindle Copyright Pearson Prentice Hall

Individual chromosomes Mitosis Anaphase Individual chromosomes Anaphase Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Anaphase Anaphase is the third phase of mitosis. The sister chromatids separate into individual chromosomes. The chromosomes continue to move until they have separated into two groups. Individual chromosomes Copyright Pearson Prentice Hall

Nuclear envelope reforming Mitosis Telophase Nuclear envelope reforming Telophase Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis Telophase Telophase is the fourth and final phase of mitosis. Chromosomes gather at opposite ends of the cell and lose their distinct shape. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Mitosis A new nuclear envelope forms around each cluster of chromosomes. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Cytokinesis Cytokinesis Cytokinesis Copyright Pearson Prentice Hall

During cytokinesis, the cytoplasm pinches in half. Each daughter cell has an identical set of duplicate chromosomes

Copyright Pearson Prentice Hall Bellwork: Thurs. Nov. 4, 2010 Series of events cells go through as they grow & divide is called cell cycle. mitosis. interphase. cytokinesis. Copyright Pearson Prentice Hall

Longest phase in mitosis is prophase. metaphase. anaphase. telophase. 10-2 Longest phase in mitosis is prophase. metaphase. anaphase. telophase.

Copyright Pearson Prentice Hall 10-2 Longest phase in cell cycle is interphase. cytokinesis prophase metaphase Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall DNA replication takes place during the S phase of the cell cycle. G1 phase of the cell cycle. G2 phase of the cell cycle. M phase of the cell cycle. Copyright Pearson Prentice Hall

Copyright Pearson Prentice Hall Bellwork: Thurs. Nov. 4, 2010 During mitosis, “sister” chromatids separate from one another during telophase. interphase. anaphase. metaphase. Copyright Pearson Prentice Hall