Mitosis and the Cell Cycle Cell Reproduction How

Mitosis and the Cell Cycle Cell Reproduction

How do little elephants grow up to be BIG elephants?

Why do animals shed their skin?

Three reasons why cells reproduce by asexual reproduction: • Skin cancer • the abnormal growth of skin cells • most often develops on skin exposed to the sun • Cell that reproduce by asexual reproduction reproduce constantly. 1. Growth 2. Repair 3. Replacement

Genetic material of eukaryotic cells is organized in chromosomes. – DNA- a double helix shaped molecule. The molecule is wrapped around proteins like thread around a spool and compacted into structures called chromosomes. – Chromosomes- right before division of the cell, the chromosomes duplicate themselves and are held together. This is called chromatid, which is held together by a centromere.

Some Definitions • Somatic Cells – Greek translated sōma - body cells, has 46 chromosomes • Gametic Cell (Greek translated gamete = wife, gametes = husband), sex cells (sperm and egg) Has 23 chromosomes • Haploid – total of 23 chromosomes in people, gametes (sperm & egg) • Diploid – total of 46 chromosomes in people – zygote & somatic cells

Mitosis • happens in all cells • a cell division process that produces two daughter cells with the same number and kinds of chromosomes as the parent cell • 5 major stages

Interphase occurs before mitosis begins • Chromosomes are copied(# doubles) • Chromosomes appear as threadlike coils (chromatin) at the start, but each chromosome and its copy (chromosome) change to sister chromatids at end of this phase. chromatid Nucleus CELL MEMBRANE Centromere Cytoplasm

Interphase Animal Cell Plant Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Prophase • Mitosis begins (cell begins to divide). • Centrioles (or poles) appear and begin to move to opposite ends of the cell. • Spindle Fibers form between the poles. Sister chromatids Centrioles Spindle fibers

Prophase Animal Cell Plant Cell Spindle fibers Centrioles Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm

Metaphase • Chromatids (or pairs of chromosomes) attach to the spindle fibers. Centrioles Spindle fibers

Metaphase Animal Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm Plant Cell

Anaphase • Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Centrioles Spindle fibers

Anaphase Animal Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm Plant Cell

Telophase • Two new nuclei form. • Chromosomes appear as chromatin (threads rather than rods). • Mitosis ends. Nucleus Chromatin Nucleus

Telophase Animal Cell Photographs from: http: //www. bioweb. uncc. edu/biol 1110/Stages. htm Plant Cell

Cytokinesis occurs after mitosis • Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

Animated Mitosis Cycle http: //www. cellsalive. com/mitosis. htm • Interphase • Prophase • Metaphase • Anaphase • Telophase & Cytokinesis

IPMATC • • • Interphase: Prophase: Metaphase: Anaphase: Telephase: Cytokinesis: Interesting People Make A Terrific Conversation

The Cell Cycle • The sequence of growth and division of a cell • 95% of cell cycle is spent in interphase. • 5% of cell cycle in is spent in mitosis.

The Cell Cycle Interphase (most of the cell’s life) • Growth Stage 1 (G 1) – metabolic activity of the cell • Synthesis Stage (S) – replication of DNA • Growth Stage 2 (G 2) –prepares for division • Mitosis Stage (M) – cell division

Cell Cycle

• United Streaming - Mitosis and Meiosis 14 min. • http: //www. pbs. org/wgbh/nova/baby/divide. html#

- Cell Division The Cell Cycle 28 28