G 2 Prophase Prometaphase Name the structures and describe what is happening.
Prophase Chromatin fibers coil to become dense chromosomes They join at the centromere as sister chromatids 2 centrosomes made in G 2
Prophase Nucleolus Disappears Spindle Fibers Form as microtubules out from the centrosomes (MTOC) Asters form (shorter microtubules extending from centrosomes)
See the chromosomes condense Centrosomes move away from each other, propelled by the lengthening microtubules between them Mitosis Animation (show through prophase)Mitosis Animation (show through prophase)
Prometaphase Nuclear envelope disintegrates (vesicles) Each sister chromatid has a kinetochore at centromere Kinetochore spindles attach to kinetochore Non-kinetochore spindles pole to pole
Prometaphase How many chromosomes are there? How many sister chromatid pairs are there? ANSWER: 4, 4
Kinetochore : attach spindle fibers to chromatid Kinetochore in pink
Kinetochore * Microtubule dynamics animation (+/- ends, jerking) Microtubule dynamics animation Spindle microtubules at centromere During prometaphase some spindle microtubules attach to the kinetochores Chromosomes tug of war to poles begins
McGraw-Hill Mitosis and Cytokinesis Microtubules lengthen and shorten by the addition or removal of tubulin. Kinetochore microtubules shorten in the region of the kinetochore, pulling the chromosomes apart. Polar microtubules elongate to push against each other and thus, push the two centrosomes apart.
COOL SITE ** GO TO Biovision: Inner life of a cell- Harvard (microtubules build and break down) NARRATED VERSIONBiovision: Inner life of a cell- Harvard
REAL FOOTAGE Animations Scroll down to Chapter 10Animations Microtubule dynamics in prophase Capture of a kinetochore Alignment of chromosomes Aligned chromosomes oscillate continuously – jerking AND MUCH MORE
Metaphase Anaphase Telophase Name the structures and describe what is happening.
Metaphase Centrioles now at opposite poles Sister chromatids line up at the metaphase plate (equator) Each chromosome has its own kinetochore coming from opposite poles
Anaphase Spindle fibers pull the chromatids to the opposite poles Centromere split Nonkinetochore microtubules lengthen
Telophase Chromatids are now at the opposite ends of the cell Late: Chromatids back to chromatin Spindles dissolve Reforming of nucleolus and nuclear envelope
Practice Links Animal Cell Mitosis Plant and Animal Cell MitosisPlant and Animal Cell Mitosis Nice Mitosis Animal CellsNice Mitosis Animal Cells Mitosis World (yes, it is as good as Disney World)Mitosis World