https://www. youtube. com/watch https://www.youtube.com/watch?v=lpAa4TWjHQ4&list=PLwL0Myd7Dk1F1pp-DaLx3ygO_7xA-yyd4&index=2

Cell Cycle The sequence of growth and division of a cell

Why can’t most organisms be just one giant cell?

Diffusion becomes slow and inefficient as the distances become larger. The cell would either starve to death or be poisoned from the buildup of waste products.

The majority of a cell’s life is spent in the period known as interphase.

Interphase – Cell is growing and DNA is replicated (copied) It consists of G1 phase - the cell grows and protein production is high S phase - DNA is synthesized and copied G2 phase –organelles are manufactured G1

After Interphase a cell divides. Cell division consists of M phase = MITOSIS (nuclear division) Cytokinesis http://esminfo.prenhall.com/science/BiologyArchive/lectureanimations/closerlook/mitosis.html G1

The end result of cell division are 2 new genetically identical cells are produced from one parent cell Same DNA

DNA CAN BE: SPREAD OUT IN NON-DIVIDING CELLS (interphase) = SCRUNCHED UP IN DIVIDING CELLS (mitosis)= CHROMATIN CHROMOSOMES

Mitosis Nuclear division

Phase 1: Prophase Chromatin condenses - chromosomes are visible

Phase 2: Metaphase Chromosomes move to the equator Spindle fibers attach to the centromeres (middle of chromosomes)

Phase 3: Anaphase centromeres split sister chromatids are pulled apart to opposite poles of the cell.

Phase 4: Telophase Two new nuclei are formed – nuclear membrane reappears

After mitosis…Cytokinesis the cytoplasm divides (cytokinesis), separating the two new identical daughter cells http://www.abpischools.org.uk/res/coResourceImport/modules/celldiv_cancer/fullscreenflash4-2.cfm

Cytokinesis in Animal Cells plasma membrane pinches in forming 2 new separate cells.

Cytokinesis in Plant Cells plasma membrane does not pinch in (because of rigid cell wall) A cell plate forms across the cell’s equator…eventually forming a new cell wall.

Why is cell division beneficial? In unicellular organisms cell division is used for reproduction (asexual) Ex. Bacteria reproducing In multicellular organisms cell division is used for growth and repair Ex. Humans producing new skin cells http://videos.howstuffworks.com/discovery/31977-assignment-discovery-cell-reproduction-video.htm

Asexual reproduction in unicellular organisms offspring are genetically identical to parent – clones no variation in the species occurs in single-celled organisms only one parent achieved without fertilization

Types of asexual Reproduction Binary fission Budding Sporulation Regeneration Vegetative propagation

1. Binary Fission Cell splits into two identical daughter cells Cytoplasm divides equally Ex.: Bacteria Ameba Paramecium http://highered.mcgraw-hill.com/sites/9834092339/student_view0/chapter10/animation_-_cell_division.html

2. Budding one of the daughter cells develops as a smaller protrusion from the other Unequal division of cytoplasm Ex: Hydra Jelly fish Yeast

3. Sporulation Parent releases hundreds of (spores) identical copies of itself Spores are surrounded by a tough coat to help them survive harsh environmental conditions. Ex: Molds mushrooms

4. Regeneration the replacement or regrowth of lost or damaged body parts Ex: usually invertebrates (exception are lizards) sea stars Crabs Lobsters Worms

5. Vegetative Propagation Occurs only in plants New plants develop from the roots, stems, or leaves of the parent plant

Types of Vegetative Propagation Cuttings (Grafting) - a plant part which is cut from the parent plant in order to regenerate itself, thereby forming a whole new plant.

Bulb Ex. Onion contains an underground stem. As the plant grows and develops it will form a new bulb underground. Ex. Onion

Tubers New plants will grow out of swollen, modified roots called tubers. Buds develop at the base of the stem and then grow into new plants. Ex. Potato

Runner stems that grow horizontally above the ground. They have nodes where buds are formed. These buds grow into a new plant. Ex. Strawberries

What is the advantage of sexual reproduction over asexual reproduction? Genetic variation - Increased chance of survival in changing environment

Binary fission Vegitative Propagation Budding Sporulation