The Cell Cycle and Mitosis Cell Division The Cell Cycle and Mitosis

Why do cells divide? Growth Repair Reproduction

Chromosomes Carry genetic information from one generation of cells to the next Not visible in cells except in cell division

Cell Division Process by which a cell divides into two daughter cells Before division, the cell replicates all its DNA Each daughter cell will get one complete set of genetic information

Cell Division- Prokaryotes Binary fission: asexual cell division of prokaryotes that produces identical offspring Three Steps: DNA is copied Cells begin to divide Two identical cells

Binary Fission Bacterial cell dividing by binary fission E. Coli dividing by binary fission

Cell Division- Eukaryotes Nucleus first and then the Cytoplasm divides There are two kinds: Mitosis Meiosis Cell cycle: set of events making up the life of a cell; composed of interphase and cell division

The Cell Cycle

Interphase The time between cell divisions where the cell spends most of its life Cell is in a resting phase, performing cell functions Composed of G1, S and G2 phases

Interphase

Interphase: G1, S, G2 G1 (Gap 1)- Cells grow to mature size S (Synthesis)- DNA is copied G2 (Gap 2)- cell organelles grow and prepare for division

Mitosis Division of nucleus Daughter Cells wind up with the same # of chromosomes There are 4 phases: 1. prophase 3. anaphase 2. metaphase 4. telophase

Prophase Chromosomes become visible Centrioles separate and move to opposite sides of nucleus Spindle fibers form

Prophase Nucleolus disappears Nuclear Envelope breaks down and disappear Prophase is the longest phase of cell division

Prophase

Metaphase Chromosomes line up along the equatorial plate (middle of the cell) Chromosomes connect to spindle fibers at centromere Metaphase is the shortest phase

Metaphase

Anaphase Sister chromatids separate and move to opposite poles When chromatids separate, they are considered individual chromosomes.

Anaphase

Telophase Nuclear envelope forms around each group of chromosomes Chromosomes relax back into chromatin Spindle fibers disassemble. Cytokinesis begins

Telophase

Cytokinesis The process by which the cytoplasm divides and one cell becomes two individual cells Different in plants and animals Animals- cell pinches inward to form a cleavage furrow Plants- a cell plate forms between the two new cells forming a cell wall

Cytokinesis- Animal Cell

Cytokinesis- Plant Cell

Cytokinesis- Plant vs. Animal