Mitosis and Cytokinesis Chapter 5: Cell Growth and Division Section 5.2 Mitosis and Cytokinesis
Vocabulary CHROMOSOMES Chromosome Histone Chromatin Chromatid Centromere Telomere Prophase Metaphase Anaphase telophase CHROMOSOMES CHROMOSOMES Make a word web to organize your notes after you read the section.
Chapter 5: Cell Growth and Division Section 5 Chapter 5: Cell Growth and Division Section 5.2 Mitosis and Cytokinesis Main Idea 1: Chromosomes condense at the start of mitosis. A chromosome is a long thread of DNA that contains genes and regulatory information. Interphase: loosely organized, (spaghetti) DNA is called chromatin Genes are easily accessed by proteins that will read the genes (containing instructions for other proteins) or will read the entire sequence of DNA on one chromosome. During synthesis, DNA is replicated, making 2 complete sets of DNA within the cell. When mitosis begins, the duplicated chromosomes must condense in order to be separated into 2 complete sets for the new cells.
Chapter 5: Cell Growth and Division Section 5 Chapter 5: Cell Growth and Division Section 5.2 Mitosis and Cytokinesis Main Idea 1: Chromosomes condense at the start of mitosis. HISTONES are protein molecules that are associated with DNA during most of the cell cycle. Histones help organize the DNA as it condenses. SISTER CHROMATIDS is the name for the condensed chromosome. It forms an “X” shape. A CHROMATID is one-half of the duplicated chromosome. Sister chromatids are held together at the centromere, a region where the chromosomes look pinched. The ends of the DNA molecules form TELOMERES, which do not contain genes. They prevent tangling of the DNA and loss of the DNA.
Chapter 5: Cell Growth and Division Section 5 Chapter 5: Cell Growth and Division Section 5.2 Mitosis and Cytokinesis Main Idea 2: Mitosis and Cytokinesis produce two genetically identical daughter cells. Interphase provides a critical time for duplication or organelles and for copying DNA. Mitosis divides a cell and its nuclear material into two genetically identical cells. Mitosis occurs in every cell in your body (somatic cells) EXCEPT egg and sperm cells (germ cells or gametes).
Chapter 5: Cell Growth and Division Section 5 Chapter 5: Cell Growth and Division Section 5.2 Mitosis and Cytokinesis Mitosis Prophase: chromatin condenses into chromosomes, each consisting of two sister chromatids; nuclear envelope breaks down, nucleolus disappears, centrosomes and centrioles migrate toward opposite sides of the cell; microtubules (spindle fibers) grow from the centrioles and radiate toward the center of the cell. Metaphase: spindle fibers attach to the centromere of each chromosome, aligning each along the middle of the cell. Anaphase: sister chromatids separate; spindle fibers shorten, pulling each sister chromatid away from the other towards opposite sides of the cell. Telophase: a set of identical chromosomes is at each pole of the cell; nuclear membranes start to form; chromosomes begin to uncoil, spindle fibers disappear.
Chapter 5: Cell Growth and Division Section 5 Chapter 5: Cell Growth and Division Section 5.2 Mitosis and Cytokinesis Cytokinesis: divides cytoplasm in two. Animal cells form a furrow which gradually pinches the cell in two. Plant cells form a cell plate between the two nuclei. The cell plate is created by the Golgi apparatus. Cytoplasm is divided evenly between daughter cells.