Mitosis and Meiosis written by: Brianne Bagan Alejandro Corral Dylan Frick Chandler Gallegos
Chapter One: Overview of the cell cycle G1 Phase During the G1 phase or the Gap 1 phase, the protein synthesis and the RNA synthesis within the cell resumes that was interrupted during the process of mitosis. Growth and young cell matura=on occurs. G1 phase is the phase during which the cell cycle starts with the synthesis of RNA and proteins required by the young cells for their growth and maturity. The =me period of the G1 phase of the interphase is varied highly among the different species eukaryo=c cells. G1 phase is usually termed as the prior to DNA synthesis phase.
S Phase S phase: Soon ager the G1 phase, DNA checking and subsequent repair occurs during the variable pause phase before the transi=on of the cell cycle to the S phase. The S phase of the interphase deals with the semi- conserva=ve synthesis of DNA occurs. Replica=on of cellular DNA begins with the S phase, which when gets duplicated with the cell containing nearly double the amount of chromosomes, the cells from the S phase move into the G2 phase.
G2 Phase During the G2 phase, there is an increase in the synthesis of the RNA and the protein, which is followed by another round of proof reading and subsequent repair among the newly synthesized DNA sequences before the cell cycle transits to the mito=c cycle. The mito=c spindle formed from the cytokine=c fibers start forming and the cell ensures the number of chromosomes and the organelles present, which further leads the cell cycle from the interphase to the mito=c phase.
Brain cells are in G 0 phase and do not replace itself. A skin cell stays in each phase of the cell cycle for at least 22 hours. 3 Foxy Facts 1. Ac=va=on of each phase is dependent on the proper progression and comple=on of the previous one. 2. Cells that have temporarily or reversibly stopped dividing are said to have entered a state called G0 phase. 3. Regula=on of the cell cycle involves processes crucial to the survival of a cell, including the detec=on and repair of gene=c damage as well as the preven=on of uncontrolled cell division.
Chapter Two: Cancer Uncontrollable Cell Division The organs in our body are made up of cells. Cells divide and mul=ply as the body needs them. When these cells con=nue mul=plying when the body doesn't need them, the result is a mass or growth, also called a tumor. Examples: Tobacco, various chemicals, viruses, dietary factors, radia=on sources and sunlight. Chapter Four: Meiosis Overview The purpose of meiosis is to reduce the normal diploid cells, to haploid cells, called gametes. If meiosis didn t occur, an egg or sperm could end up with too many chromosomes, or not enough chromosomes.
Chapter Five: Meiosis I Meiosis begins with Interphase I. During this phase there is a duplication genetic material, DNA replication. The chromatin remains in a nuclear envelope while a pair of centrioles lies inside a centrosome. During Prophase I, the chromatin condenses into chromosomes, the nuclear envelope disappears, and a spindle apparatus begins to form. Each chromosome consists of a pair of chromatids connected by a centromere. The major occurrence in this phase is the coupling of these homologous chromosomes. Two double- stranded chromosomes form a four- stranded tetrad. In Metaphase I, the tetrads line up on the "equator" of the cell. The centrosome has replicated and one has moved to each pole. Microtubules that extend out of each centrosome attach to kinetochores in the center of each side of the tetrads that have lined up on the equator. Anaphase I occurs as the microtubules pull the pairs of homologous chromatids toward each pole, as the tetrad is divided. The cell begins to lengthen. During Telophase I, the nuclear envelope begins to reform and nucleoli reappear. The cell begins to split, forming a cleavage furrow in the middle.