The continuity of life… REPRODUCTION The continuity of life…
What Is Reproduction? Reproduction is the process by which organisms produce more of their own kind…can be sexually or asexually Think about it…Without it…all life on earth would cease to exist
Types of Asexual Reproduction Binary Fission… Budding… Spore production Regeneration Propagation Vegetative Artificial Cloning
1. Binary Fission… The nucleus divides by mitosis and the cytoplasm divides, forming 2 new daughter cells of equal size. Occurs in single celled organisms …bacteria, protists…amoeba, paramecium
2. Budding… The division of cytoplasm is unequal so one of the daughter cells is larger than the other. The daughter cells can separate or remain attached.
Budding… New Organisms Arise as an Outgrowth from the Parent Organism Seen Mostly in Marine Animals Examples Include; Sponges, Corals and Jellyfish… Also seen in yeast and Hydra Coral Polyp Photo courtesy Jeffrey N. Jeffords http://oceanworld.tamu.edu/students/coral/coral1.htm
3. Sporulation… Spores are produced in large numbers by mitosis. Spores are surrounded by a tough coat to help them survive harsh environmental conditions. Seen in mosses, fungi…mushrooms, molds
4. Regeneration… This refers to the ability of some animals to re-grow severed parts. Some of these animals can also grow new organisms from the severed pieces Segmented Worms and Sea Stars
5. Propagation VEGETATIVE New plants develop from the roots, stems, or leaves of the parent plant. Three Types Tubers Bulbs runners
Tubers Tubers are underground food stores which stores food over the winter and provides a new plant with food until it can make its own. Examples: potato, artichoke, yam, water chestnut, arrowroot Tuber info from http://www.foodsubs.com/Tubers.html Taro- Japanese potato Food made by the new plant is sent to make new tubers. Thereby reproducing itself.
Bulbs E.g. daffodils, lilies
Runners Runners are side shoots which grow out from the parent plant. Buds form at points along the runner and eventually these buds form roots and grow into new plants. Examples: spider plant (Anthericum), strawberry (Fragaria x ananassa)
Propagation Artificial With plants, but with human intervention Two main types Cuttings Grafting
Cutting They can be placed in moist soil or water (and sometimes Cuttings are small pieces of stem with some leaves attached, the new plant grows from this. SQA- Describe ways of propagating flowering plants artificially by cuttings and graftings Source counties.cce.cornell.edu/.../propagation.htm They can be placed in moist soil or water (and sometimes dipped in rooting powder).
Grafting A cut stem of one plant (with good flower or fruit growth) (the graft) is taken and firmly attached to the rootstock of another plant (which has a strong, established root system) (the stock). Examples- roses, fruit trees
Cloning A type of asexual reproduction performed in a laboratory that produces an identical individual from a cell or cluster of cells. In plants: can be cloned using a method called tissue culture. Enables plant growers to reproduce plants that might have become infected with a disease In animals: because all chromosomes come from one parent, the clone is a genetic copy. Scientists are currently working to save endangered species
https://www.brainpop.com/science/cellularlifeandgenetics/asexualreproduction/
One parent cell (body cell) with chromosome pairs (two gene sets) Genetic information is copied then separated ONE time so each cell has same information (mitosis) Same genetic information is passed on to each new cell Offspring is identical to parent Used for growth, repair and asexual reproduction
Asexual Reproduction Advantages Disadvantages Only need one parent cell no need to find a mate Large numbers of offspring can be produced fairly quickly Fine for stable environments without change Lack of genetic variation…No diversity Share same weaknesses…one disease could wipe out entire population! Parent can pass on disease since identical to offspring
Mitosis reviewed Mitosis demonstration