1. By Brian Gross per2 Centrioles and Asters

2. Centrioles Centrioles are barrel shaped organelles found in the cells of most animals

3. Structure Centrioles are made of cylindrical microtubules There are nine triplets of these microtubules There are nine triplets of these microtubules They are arranged in a circle around the center They are arranged in a circle around the center Two are arranged in pairs that are at right angles from one another to form organelle called the centrosome Two are arranged in pairs that are at right angles from one another to form organelle called the centrosome

4. Function Centrioles play an important function in cell division The centrosome is the origin of all the cells microtubules Microtubules form cytoskeleton of the cell Microtubules form cytoskeleton of the cell

5. Overview of Cell Division Cycle G 2 of Interphase Centrosomes duplicate to form two pairs of centrioles, the microtubules that extend from it are called asters Centrosomes duplicate to form two pairs of centrioles, the microtubules that extend from it are called astersProphase Chromatin in nucleus is more tightly coiled into chromosomes, spindles form between the centrosomes, which arrange themselves on opposite “poles” of the cell Chromatin in nucleus is more tightly coiled into chromosomes, spindles form between the centrosomes, which arrange themselves on opposite “poles” of the cell chromosome

6. Cell Division Prometaphase Nuclear envelope breaks and the mitotic spindles growing from the centrioles move to center of cell Nuclear envelope breaks and the mitotic spindles growing from the centrioles move to center of cellMetaphase Centrosomes arrange themselves on opposite sides of cell, chromosomes create line on the imaginary equator of the cell, the spindles attach to each other and to the center of the X shaped chromosome, called the centromere Centrosomes arrange themselves on opposite sides of cell, chromosomes create line on the imaginary equator of the cell, the spindles attach to each other and to the center of the X shaped chromosome, called the centromere

7. Cell Division Anaphase Sister chromatids (half of one chromosome) are pulled apart, move centromere first, poles move further apart Sister chromatids (half of one chromosome) are pulled apart, move centromere first, poles move further apartTelophase The nuclear envelope begins to form in both daughter cells, chromatids begin to unravel, the cells are pinched and separated The nuclear envelope begins to form in both daughter cells, chromatids begin to unravel, the cells are pinched and separated

8. More Functions Centrioles are also important for the position of cilia and flagella in the cell When cells can’t use centrioles to create functioning cilia and flagella, it leads to genetic disorders, ex. Meckel-Gruber syndrome When cells can’t use centrioles to create functioning cilia and flagella, it leads to genetic disorders, ex. Meckel-Gruber syndrome

9. Overview Centrioles are made of nine triplets of microtubules arranged in a cylindrical shape A pair of centrioles are centrosomes, from which the cells microtubules grow Important for the cytoskeleton Important for the cytoskeleton During cell division, the centrioles duplicate and move to opposite ends of the cell and are the origin of the microtubules that pull the chromatids apart Asters are radial microtubule arrays that are located around each pair of centrioles

10. sources http://en.wikipedia.org/wiki/Centrioles http://www.gettyimages.com/Home.aspx http://www.cellsalive.com/cells/centriol.htm Campbell-Reece Biology (textbook)