Mitosis PDF

Mitosis Autosomes: Chromosomes other than sex chromosmoes. In humans chromosomes 1-22 are autosomes Cell cycle: the sequence of events that takes place between successive mitotic divisions Mitosis: form of cell division that produces 2 cells, each of which has the same complement of chromosomes as...

Mitosis Autosomes: Chromosomes other than sex chromosmoes. In humans chromosomes 1-22 are autosomes Cell cycle: the sequence of events that takes place between successive mitotic divisions Mitosis: form of cell division that produces 2 cells, each of which has the same complement of chromosomes as the parent cell Cytokinesis: the process of cytoplasmic division that accompanies cell division Mitosis has 3 stages - Interphase (18-24 hours) - Mitosis (1 hour) - Cytokinesis Life history and cell cycles vary for different cell types Interphase (3 stages) → time between divisions - G1: interval of cell growth before DNA replication (chromosomes unduplicated) - New daughter cells are half the size of parent cells; need to grow before they can divide - Begins immediately after cell division - Organelles, membranes, and ribosomes are made - This doubles the cells size and replaces organelles and cytoplasm distributed from the previous cell division - S: copy of each chromosome; chromosomes duplicated - G2: cell is ready to divide Mitosis (4 stages): a complete set of chromosomes is distributed to each daughter cell - Each daughter cell receives a full 46 chromosomes from a single parent cell containing 46 replicated chromosomes - Mitosis is a continuous process Prophase: Beginning of mitosis - Chromatid: one of the strands of a duplicated chromosome, joined by a single centromere to its sister chromatid - Centromere: a region of the chromosome to which spindle fibers attach during cell division. The location of a centromere gives a chromosomes its characteristic shape - sister chromatids: 2 chromatids joined by a common centromere - Chromosomes are usually not visible in the nucleus of non dividing cells → they are uncoiled and dispersed - @ the beginning of prophase, chromosomes condense and are recognizable - At the end of prophase the replicated chromosomes are sister chromatids & the nuclear envelope breaks down and spindle fibers form and stretch across the cell. Metaphase  - Chromosomes attached by spindle fibers attach and move to the equator of the cell - At this stage there are 46 centromeres each attached to 2 sister chromatids Anaphase - Centromeres divide converting each sister chromatid into a CHROMOSOME - Chromosomes migrate to opposite ends of the cell - There is a complete set of chromosomes at each end - Shortest phase of mitosis - Essential pase in ensuring each daughter cell received a complete and identical set of chromosomes Telophase - Chromosomes have reached opposite ends of the cell - Chromosomes uncoil/ decondense and spindle fibers break down membranes from the ER to form a new nuclear envelope Cytokinesis - First visible sign of cytokinesis is formation of a constriction called a cleavage furrow at the equator of the cell