Section 10.2 (Pg. 279-285): The Process of Cell Division
Chromosomes Are genetic information bundled into packages of DNA Eukaryote Are genetic information bundled into packages of DNA Make it possible to separate DNA precisely during cell division Are packaged differently in prokaryotes and eukaryotes Prokaryotes: small, circular chromosome Eukaryotes: multiple chromosomes Prokaryote
Eukaryotic Chromosomes Are made of chromatin DNA coils around proteins called histones DNA coiled around histones forms a unit called a nucleosome Chromosome shape is supercoiled chromatin
Prokaryotic Cell Cycle Prokaryotic cell division is called binary fission Cell grows and chromosome duplicates 2) Cell membrane pinches in 3) Cell divides into two daughter cells
The Eukaryotic Cell Cycle Is when a cell grows, prepares for cell division, then divides Is separated into two major parts: Interphase Cell division Interphase and cell division have their own phases
Interphase Is the portion of a cell’s life in between cell division G1 phase: Cell Growth Cell grows and performs normal functions S phase: DNA Synthesis DNA is copied for cell division G2 phase: Preparation for Cell Division Organelles and molecules are copied for cell division
Cell Division Is also called M phase Contains the phases of cell division Mitosis Is the division of the nucleus Has 4 separate phases Cytokinesis Is the division of the cytoplasm
DNA During Cell Division Forms replicated chromosomes Each half of the chromosome is called a sister chromatid They are held together by a centromere Is separated into daughter chromatids during cell division
Before Cell Division Cells are in interphase Nucleus is intact DNA has NOT yet formed chromosomes Centrioles are lumped together near the nucleus
Phases of Mitosis 1) Prophase Replicated chromosomes condense Nuclear envelope disappears Nucleolus disappears Centrioles move to the opposite sides of the cell Mitotic spindle forms from centrioles
Phases of Mitosis 2) Metaphase Chromosomes attach to the spindles and line up along the center (midline) of the cell
Phases of Mitosis 3) Anaphase Sister chromatids separate and move along the spindle fibers to opposite ends of the cell
Phases of Mitosis 4) Telophase Nuclear envelope re-forms around chromatids Nucleolus re-forms Chromatids uncoil into chromatin Spindle breaks apart Centrioles move near the re-forming nuclei
Cytokinesis Completes cell division by splitting the cell membrane and cytoplasm in two Different in animal and plant cells In animal cells the cell membrane pinches the cell in two In plant cells a cellulose cell plate forms in between the nuclei to make a cell wall