The Cell Cycle Cell Division The Cell Cycle

The Cell Cycle & Cell Division

The Cell Cycle http: //www. nobel. se/medicine/laureates/2001/press. html

Phases of the Cell Cycle • The cell cycle consists of – Mitotic (M) phase (mitosis and cytokinesis) – Interphase (cell growth and copying of chromosomes in preparation for cell division) • Interphase (about 90% of the cell cycle) can be divided into subphases: – G 1 phase (“first gap”) – S phase (“synthesis”) – G 2 phase (“second gap”)

Animated Cycle http: //www. cellsalive. com/cell_cycle. htm

MITOSIS

Mitosis The process of cell division which results in the production of two daughter cells from a single parent cell. The daughter cells are identical to one another and to the original parent cell.

Mitosis can be divided into stages • Interphase • Prophase • Metaphase • Anaphase • Telophase & Cytokinesis

Interphase The cell prepares for division • Animal Cell – DNA replicated – Organelles replicated – Cell increases in size • Plant Cell – DNA replicated – Organelles replicated – Cell increases in size

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

Prophase The cell prepares for nuclear division • Animal Cell – Packages DNA into chromosomes • Plant cell – Packages DNA into chromosomes

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

Metaphase The cell prepares chromosomes for division • Animal Cell – Chromosomes line up at the center of the cell – Spindle fibers attach from daughter cells to chromosomes at the centromere • Plant Cell – Chromosomes line up at the center of the cell – Spindle fibers attach from daughter cells to chromosomes at the centromere

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

Anaphase The chromosomes divide • Animal Cell – Spindle fibers pull chromosomes apart – ½ of each chromosome (called chromotid) moves to each daughter cell • Plant Cell – Spindle fibers pull chromosomes apart – ½ of each chromosome (called chromotid) moves to each daughter cell

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

Telophase The cytoplasm divides • Animal Cell – DNA spreads out – 2 nuclei form – Cell wall pinches in to form the 2 new daughter cells • Plant Cell – DNA spreads out – 2 nuclei form – New cell wall forms between to nuclei to form the 2 new daughter cells

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

Mitosis Animation http: //www. cellsalive. com/mitosis. htm

Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

Asexual Reproduction Living Environment

• Mitosis animation: • http: //brodylab. eng. uci. edu/cgibin/jpbrody/animation/files/6973887139. html

Are you two twins? • Asexual Reproduction: – Used by many unicellular organisms, plants, and lower animals. – Involves only mitotic cell division = each offspring has exactly the same heredity as its parent. – Usually rapid compared to sexual reproduction. Types of Asexual Reproduction Include:

Cut it half • Binary Fission = simplest form of asexual reproduction. Parent organism divides into two • approximately equal parts. Each daughter cell becomes a new individual.

Binary Fission

Bacteria • Bacteria – No organized nucleus. – Genetic material in the form a single circular chromosome. – Before division starts chromosome is replicated then each daughter cell gets one copy of the chromosome. – Can occur every 20 -min.

Protozoan • Protozoa – Mitosis occurs. Cytoplasm pinches in and divides the organism in half. Each half has a copy of the genetic material. Diagram.

• Protozoa – Mitosis occurs. Cytoplasm pinches in and divides the organism in half. Each half has a copy of the genetic material. Diagram.

They Where best buds • Budding = Parent organism divides into two unequal parts. • The new organism is created as a smaller out growth or bud on the outside of the parent. • Buds will brake off and live independently or remain attached and form a colony.

Budding

• Yeast – Once the yeast cell reaches a certain size it undergoes mitosis. • Once the genetic material is replicated budding begins. • Hydra – Cells on the outside of the parent hydra begin to undergo mitotic division creating a small group of cells. Those cells continue to divide until in a completely new hydra is formed. Can also reproduce sexually.

• Yeast cell cycle including budding: • http: //brodylab. eng. uci. edu/cgibin/jpbrody/animation/files/13977277560. html

Can I have some spore? • Spore Formation – spores = small specialized cells that contain a nucleus and cytoplasm surrounded by a thick outside wall which protects the spore. Under the right conditions the spore can rise to a new organism. Found in bacteria, molds, yeast, mushrooms, mosses, ferns and some protozoans.

Spore formation

Don’t try this at home • Regeneration = The ability to re-grow lost or damaged body parts. Hydra, planaria, starfish, and earthworm More complex animals less able to re-grow parts. Crab can re-grow a claw. Some reptiles can re-grow a tail. Most mammals can repair damaged tissue but can not re-grow missing parts.

Regeneration

Vegetative Reproduction

• Bulb = Short underground stem surrounded by thick leaves. Contain stored food. As the plant grows it produces new bulbs which will grow into new plants. Tulips, onions, and lilies.

• Corms = Similar to bulbs but do not contain leaves, just undergrou nd stems. Water chestnuts.

• Tuber = enlarged part of an underground stem that contains stored food. Potatoes are tubers. “Eyes” = tiny buds that can form a new potato plant. How you plant potatoes. Great potato famine.

• Runner or stolen = horizontal stem above the ground with buds. If a bud touches the ground it will form roots and stems and start a new plant. Strawberries.

• Rhizome = horizontal stem that grows underground. Thick and contains stored food. Upper portion form nodes which will form buds which will form new plants. Lower portion forms roots. Ferns, cattails, and water lilies.

Artificial Vegetative Reproduction

Watch out for those old ladies. • Cutting = use a portion of a developed plant to make a new plant. Roses, ivy, and grapevines are reproduced in this way.

• Layering = a stem is bent so that it is covered with soil. Once the branch forms roots it is disconnected from the original plant. Raspberries and roses.

• Grafting = Bud or stem of one plant is permanently attached to the stem or trunk of a very similar plant. The cambium layers grow together and form a single plant. Apple trees.

That’s a strange cacti

Why Bother? ? • Advantages to artificial vegetative propagation: 1. Plants that grow from seed are not always exactly the same as their parents. 2. Takes less time to artificially propagate. 3. Can create seedless fruits. 4. Grafting can be used to generate higher levels of fruit and nut production.

Can robot teachers from the future asexual reproduce? (Relax that was a rhetorical question)

Websites • Yeast cell cycle including budding: • http: //brodylab. eng. uci. edu/cgibin/jpbrody/animation/files/13977277560. html • Mitosis animation: • http: //brodylab. eng. uci. edu/cgibin/jpbrody/animation/files/6973887139. html