Chapter IV Part 1 Reproduction of EUKARYOTIC cell

Chapter IV Part 1 Reproduction of EUKARYOTIC cell By Pn. Aslizah Binti Mohd Aris 06 -4832168

Lectures Outline Chromosome morphology and function The cell cycle and mitosis Meiosis and gametogenesis

Cell Division

Chromosome, Bacterial

Chromosomes, Eukaryote Here “chromosome” and “DNA” are not 100% synonymous

Chromosomes vs. Chromatin Chromosomes Chromatin • Tightly packaged DNA • Found only during cell division • DNA is not being used for macromolecule synthesis • Unwound DNA • Found throughout Interphase • DNA is being used for macromolecule synthesis

Chromosomes, Eukaryote Though chromosomes are “all about” DNA, in fact much this structure consists of protein Form via replication, not by formed chromatids coming together

Chromosome Duplication & Distribution During Cell Division Chromosomes 1. A eukaryotic cell has multiple chromosome, one of which is represented here. Before duplication, each chromosome has a single DNA molecule. 2. Once replicated, a chromosome consists of two sister chromatids connected along their entire lengths by sister chromatidcohesion. Each chromatid contains a copy of the DNA molecule 3. Mechanical processes separate the sister chromatids into two chromosomes and distibute them to two daughter cells. DNA molecules

How Long is a Chromatid? q A chromatid is a chromatid as long as it is held in association with a sister chromatid at the centromere Chromosome Chromatid q When two sister chromatids separate (after metaphase) they go from being a single chromosome to being two different chromosomes

Chromosomes, Eukaryote Genome = DNA Chromosome = DNA + protein (visible light microscope) Chromatin = DNA + protein DNA (but less than for chromosome)

Some Vocabulary Centromere Centrosome Centriole Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers

Some Vocabulary Centromere Centrosome Centriole Kinetochore microtubules Mitotic spindle Recall that the Nonkinetochore centrosome is themicrotubles center of the microtubule array of Spindle apparatus a cell Spindle fibers

Some Vocabulary Centromere Centrosome Centriole Kinetochore Recall that these consist of microtubules and that a pair Kinetochore microtubules makes up a centrosome Mitotic spindle Keep in mind that the term Nonkinetochore microtubles Spindle centriole is not an exact synonym of centrosome and that apparatus centrosome is not a synonym of fibers the term centromere

Some Vocabulary Centromere Centrosome Centriole Kinetochore microtubules Mitotic spindle. Responsible for moving Nonkinetochore microtubles chromosomes relative to mitotic Spindle apparatus spindle Spindle fibers

Some Vocabulary Centromere Centrosome Centriole Kinetochore microtubules Mitotic spindle These are the portion of the mitotic spindle that is Nonkinetochore microtubles connected to chromosomes during Spindle apparatus mitosis Spindle fibers

Some Vocabulary Centromere Centrosome Centriole Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles These are the microtubles that are Spindle responsible for separating apparatus chromosomes as well as pushing the centrosomes toward opposite fibers ends of cells

Some Vocabulary Centromere Microtubules of mitotic Centrosome spindle that are not connected to the Centriole chromosomes but instead responsible for Kinetochore pushing centrosome apart Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers

Some Vocabulary Centromere The mitotic spindle as Centrosome visible through a light microscope Centriole Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers

Some Vocabulary Centromere Bundles of microtubles Centrosome making up the spindle apparatus; it is the Centriole bundling that makes them visible through a Kinetochore light microscope Kinetochore microtubules Mitotic spindle Nonkinetochore microtubles Spindle apparatus Spindle fibers

Eukaryote Cell Cycle “G” stands for “Gap”

MITOSIS Mitosis is conventionally divided into five phases: Prophase Prometaphase Metaphase Anaphase Telophase Cytokinesis is well underway by late telophase Bio. Flix: Mitosis Copyright © 2008 Pearson Education, Inc. , publishing as Pearson Benjamin Cummings

Stages of Mitosis

Mitosis (First half)

Mitosis (Second half)

Mitotic Spindle

Aster(s)

Kinetochore

Cytokinesis, Animals Cytokinesis can occur simultaneous to telophase

Cytokinesis, Plants

G 2 of Interphase Nucleus defined Nucleoli present Replicated Centrosomes Asters present DNA duplicated DNA still chromatin

Prophase Chromatic condensation Nucleoli disappear Mitotic spindle forms Centrosome separation

Prometaphase Nuclear envelope fragments Microtubules invade nucleus Microtubles interact chromosomes Kinetochores at centromeres Chromosomes jerky movements Nonkinet. microtubule interaction

Metaphase Centrosomes opposite poles Metaphase plate Chromosomes straddle MP Kinetochores attached KMT Spindle apparatus Brief, static phase

Anaphase Begins with “sister” separation Chromatids now chromosomes “Sisters” to opposite poles Movement centromere first Non-kinet. microtu. lengthening Further separation of poles

Telophase Non-kinet. microtu. lengthening “Sisters” at opposite poles Nuclear env. reformation Reforms from endomembrane Chromosome decondensation Cytokinesis already under way

Cytokinesis: A Closer Look In animal cells, cytokinesis occurs by a process known as cleavage, forming a cleavage furrow In plant cells, a cell plate forms during cytokinesis Copyright © 2008 Pearson Education, Inc. , publishing as Pearson Benjamin Cummings

Cytokinesis Cleavage Furrow