V

Cell Cycles

Cell cycle: a series of phases that a cell passes through to allow them to divide and produce new cells

Interphase: cell grows, performs routine life processes, and prepares to divide. Spends most of its life in this stage

G1: cell growth, performing routine metabolic processes

S phase: DNA is synthesized (DNA replicated)

G2: growth and final preparation for division, checks the cell to prepare for mitosis

Mitosis: the most important organelle in a eukaryotic, which is the nucleus, divides

Prophase: the nuclear membrane (envelope) starts to disappear; chromosomes form

Metaphase: chromosomes line up in the middle of the cell; spindle fibers attach to chromosomes at the centromere

Anaphase: sister chromatids move to the opposite ends of the cell; ½ of each chromosome (chromatid) moves to each daughter cell

Telophase: 2 nuclei develop, nuclear membrane (envelope) reappears

Cytokinesis: cell divides into 2 identical daughter cells

Cancer

  • Disease caused when cells divide uncontrollably and spread into surrounding tissues

    • What is supposed to help with preventing cancer in your body? Genes that code for proteins that monitor cell division during mitosis and discourage unwanted cell growth.

    • How do cancer/tumors form? SOME mutations can change the proteins responsible for regulating cell growth and division.

    • NO regulation = things not working properly = cancer or tumors

Meiosis

  • Cell division that creates gametes (gametes are genetically different)

    • All are haploid cells (one copy of chromosomes) (half set of DNA)

  • Only purpose is to produce cells for sexual reproduction

  • Meiosis 1

    • Prophase 1: starts as diploid cell (full set), DNA condensed into chromosomes, nucleus dissolves

      • Crossing over: increases genetic variation of cells

    • Metaphase 1: homologous pairs of chromosomes line up next to each other in the middle, independent assortment occurs

    • Anaphase 1: homologous chromosomes are pulled toward opposite sides of the cell by microtubules

    • Telophase 1: two nuclei form, cytoplasm divides and forms two new haploid cells (half DNA set)

  • Meiosis 2

    • Prophase 2: DNA condenses, nuclear membrane dissolves

    • Metaphase 2: chromosomes line up in the middle

    • Anaphase 2: chromosomes separate to opposite sides of the cell

    • Telophase 2: two nuclei form again

    • Cytokinesis 2: cell divides, now ends with FOUR haploid sex cells (gametes)