Asexual Reproduction © Lisa Michalek. Asexual Reproduction Results from the mitotic cell division...

Asexual Reproduction

© Lisa Michalek

Asexual ReproductionResults from the mitotic cell division (Mitosis).

One cell (parent cell) divides into two identical daughter cells.

The offspring are genetically identical to the parent cell.There is no fusing (joining) of cells in this type of reproduction.

Unicellular and multicellular plants can reproduce both asexually and sexually.Common types of asexual reproduction include:

Binary FissionBuddingSporulationRegenerationVegetative Propagationcloning

Binary Fission

Simplest type of asexual reproduction.A one-celled organism divides by mitosis to form two daughter cells of equal size.Both the nucleus and cytoplasm divide equally.The chromosomes of the offspring are identical to that of the parent.

BinaryFission

Binary Fission

Example organisms: amebas, paramecia, bacteria

BuddingA new organism develops as an outgrowth of the parent.The new organism, called the bud, is a tiny duplicate of the parent organism.The nucleus divides equally and the cytoplasm divides unequally.The bud and the parent may separate from each other or may remain together and form a colony.

Budding

Unicellular organism: YeastMulticellular organism: Hydra

SporulationSpores are specialized asexual reproductive cells that contain a nucleus and a small amount of cytoplasm.Spores are surrounded by tough protective coats that enable them to survive in extreme heat or cold, for long periods of time.When environmental conditions become favorable, each spore can develop into a new organism.

Sporulation

Formation of spores occurs in bread mold, mushrooms, mosses and ferns.

Regeneration

The development of a new organism from a part of the parent organism.

Example: In starfish, a single arm can develop into a new starfish.

Starfish eat oysters and oyster fishermen once tried to kill starfish by cutting them into pieces. Instead of dying, each starfish piece grew into a new starfish.

Regeneration can also mean the replacement of lost body parts.Regeneration of lost body parts occurs mostly in invertebrates.

Example: Lobsters are able to grow a new claw to replace one that has been lost.Other Examples: planaria and sponges

Vegetative PropagationA form of asexual plant reproduction.A part of a plant– a root, stem, or leaf, grows into a new plant.The new plant is exactly the same as the parent plant.Seedless fruits and vegetables have to be reproduced by this method.Growers use this type of reproduction because it is fast, easy to use, and usually successful.

Natural Vegetative PropagationTubers – Underground stems that contain stored food. White potatoes are tubers. The “eyes” of the potato are buds, which can develop into new plants.

Natural Vegetative PropagationRunners – Stems that grow out over the surface of the soil from the existing stem.At points along the runner, new plants grow.Runners occur in strawberries and some grasses.

Natural Vegetative PropagationRhizomes – Long, modified stems that grow horizontally under the soil.New plants are produced at nodes along the stem.Lawn grasses, ferns, and irises reproduce by rhizomes.

Natural Vegetative PropagationBulbs – Underground stems specialized for food storage.The food is stored in the thick leaves of the bulb.Each bulb can develop into a new plant.Onions are bulbs.

Artificial Vegetative Propagation

Occurs as the result of human activities.Cuttings – pieces of roots, stems, or leaves develop into new plants under proper conditions.Roses, sugar cane, and bananas are propagated this way.

Artificial Vegetative Propagation

Grafting – A cutting from one plant, called the scion, is attached to the main body of a rooted plant, the stock.The scion keeps its own identity.Seedless oranges and grapes are propagated by grafting.