Cell Division Chapter 10 Cell Limitation As Cell

Cell Division Chapter 10

Cell Limitation �As Cell Grows: �Stops growing before too large �It divides, forming two cells

Cell Division Process by which the cell divides into two new daughter cells.

Chromosomes Carries genetic information that is passed from one generation of cells to the next DNA only visible during cell division every organism has a specific number

Terms Sister Chromatids: two identical copies of the chromosome Centromeres: attaches the chromatids together.

series of events that cells go through as they grow and divide Interphase: period of the growth of the cell M phase Cell Cycle

Interphase • Divided into three phases: • G 1 (growth) • S (replication of DNA) • G 2 (preparation for mitosis)

Mitosis �Divided into four phases: �Prophase �Metaphase �Anaphase �telophase

Prophase Chromatin condenses Centrioles separate Spindle begins to form Nuclear envelope breaks down

Metaphase Chromosomes line up across center Spindle fiber connected to centromere

Anaphase Sister chromatids separate into chromosomes Sister chromatids move apart

Telophase �Chromosomes gather at opposite ends �Chromosomes lose distinct shape � 2 nuclear envelopes form

Cytokinesis (splitting into two) �occurs at the same time as telophase. �Animals: The cell membrane is drawn inward until it is pinched into �Plants: cell plate forms midway between the cell

Cell Cycle Regulators �Tells cells when it is time to divide and duplicate chromosomes �Cyclin: protein that regulates the timing of the cell cycle in eukaryotic cells �Two different types: �Internal Regulators �External Regulators

Internal Regulators �Proteins that respond to events inside the cell �Allow the cell cycle to proceed only when certain processes have happened inside the cell. �EX: some regulators make sure that a cell does not enter mitosis until all its chromosomes have been replicated.

External Regulators �Proteins that respond to events outside the cell �Direct cells to speed up or slow down the cycle. �Growth factors: stimulate the growth and division of cells. �Prevent extensive cell growth and keep the tissues of the body from disrupting each other

Uncontrolled Cell Growth �Cancer: �cells lose the ability to control growth. �Does not respond to the signals that regulate the growth �Form tumors

�Benign: not cancerous �Malignant: Cancerous

Meiosis �Terms: �Homologous: each of the chromosomes that come from the male parent and female parent. �Diploid (2 N): contains both sets of homologous chromosomes (two sets). �Haploid (N): contains only a single set of chromosomes (single set)

Meiosis �the number of chromosomes is cut in half �Two cell divisions: Meiosis I and Meiosis II �End Result: 4 haploid cells

Meiosis I Interphase I Prophase I: chromosomes pair with its corresponding homologous chromosome Crossing over Metaphase I, Anaphase I, Telophase I

Meiosis II �second meiotic division �Prophase II: Neither cell goes through a round of chromosome replication �Metaphase II, Anaphase II, Telophase II

Gamete Formation: Males: sperm Produces 4 haploid sperm cells Females: eggs Produces 1 haploid egg cell Receives most of the cytoplasm Polar bodies

Mitosis and Meiosis Results: two genetically identical diploid cells Begins with a diploid cells and ends with a diploid cell Involved in asexual reproduction Results: four genetically different haploid cells. Begins with a diploid cell and ends with a haploid cell Involved in sexual reproduction