Asexual Reproduction

Asexual Reproduction Asexual Reproduction is a result of Mitotic Cell Division. Parent cells divide into two identical daughter cells. In asexual reproduction the offspring are genetically identical to the original. In asexual reproduction there is no fusing of sex cells. Unicellular algae and multicellular plants can reproduce either sexually or asexually. Asexual reproduction is not as complex and requires far less energy. It can be done relatively rapidly. Different types of asexual reproduction are: Binary Fission, Budding, Sporulation, Regeneration, Vegetative Propagation and Cloning.

Binary Fission Simplest type of asexual reproduction. Binary Fission involves a one celled organism. Binary Fission produces 2 new daughter cells. Binary Fission begins with DNA but doesn’t exchange genetic info. The cells produced are genetically identical to each other and to the parent cell.

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.

Reproduction in Unicellular Organisms 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. Protozoans (e.g. ameba or paramecium) Mitosis occurs in the nucleus. Cytoplasm pinches in and divides the organism in half. Each half has a copy of the genetic material. Algae—cell plate divides cell in half.

Budding This is when an offspring grows out of a parent. Hydras and yeast are examples of budding. In a single cell the nucleus divides equally by mitosis but the cell’s cytoplasm divides unequally to form a bud. The parent and offspring may stay connected and form a colony or separate.

Budding in Hydra Hydra is a simple multicellular organism that can reproduce by budding or sexually.

Sporulation Occurs in molds, mushrooms, mosses and ferns. Spores are produced in large numbers by mitosis. Spores are surrounded by a tough coat to help them survive harsh environmental conditions.

Regeneration Refers to replacement or regrowth of lost or damaged body parts. Can result sometimes in a new organism being produced. Regeneration can occur in starfish, sponges and in planaria. So if a starfish gets an arm torn off it can be made into a new starfish.

Vegetative Propagation It is when a part of a plant grows into a new plant. Everything but seed reproduction is considered vegetative propagation. Vegetative propagation can occur naturally or unnaturally. Types of natural vegetative propagation are tubers, runner, rhizomes and bulbs. Types of unnatural vegetative propagation are cuttings and grafting.

Vegetative Propagation Runners Stems grow on top and across the ground from the existing stem. From the runner new plants grow Some examples are strawberries and some grasses. Bulbs Underground stems for food storage Food stored in fleshy leaves Each bulb develops into a new plant. Tulips, onions, and lilies are examples of bulbs.

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

Vegetative Propagation Tubers Underground stems that contain stored food. The eyes of potato can develop into new plants. Potatoes are one example of tubers. Rhizomes Long modified stems that grow horizontally under the ground. New plants grow off the roots. Long grasses, ferns, and irises are examples of rhizomes.

Artificial Vegetative Propagation Cuttings Pieces of a root or stem that in certain conditions are made into new plants. Some examples are bananas, roses and sugar cane Grafting Taking a part of a plant and connecting it to another one. Combining the two plants. Some examples are seedless oranges and grapes. The rooted portion is the stock, the graft is called the scion.

Layering = a stem is bent so that it is covered with soil 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.

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.