By Dr Adrian Mascia (Ph.D Biology, Education. M, 2009, teacher of the year

TYPES OF REPRODUCTION Reproduction: The creation of a new generation of single cells, single celled organisms or multi-cellular organisms. The production of new organisms will always begin with the division of a single cell. A–sexual: Reproduction without the assistance of another organism Sexual: Requires two organisms of the same species to combine gametes to form a zygote

A-SEXUAL REPRODUCTION There are several methods of A-sexual reproduction 1.Fission 2.Spore formation 3.Budding 4.Fragmentation 5.Vegetative reproduction A-sexual reproduction is very rapid, however does not provide genetic diversity, this can put at species at risk of extinction should conditions change

Fission Fission involves the replication of chromosomal DNA Once replication occurs, the DNA strands are attached at opposing ends of a cell membrane, and cell division occurs (giving rise to 2 identical cells) This is a very rapid process (exponential) E.G Amoeba

Spore Formation Spores are hardy, self contained capsules containing DNA Spores are generally mass produced, and are very effective as they will only leave their dormant state when conditions become suitable (increasing chance of survial) E.G ferns, mosses, some prokaryotes and protists

Budding Budding involves the development of a new organism from the out growth of a parent organism. The new organism may detach at some point and become a stand alone organism E.G Hydra, some flat worms, yeast cells

Fragmentation Some organisms such as sponges have the ability to fragment as well as re- construct themselves A sponge can be broken into many pieces, forming many new organisms Can also reform a new organism from fragments

Vegetative Propagation There are some species of plants from which you can regrow a clone of the original plant by planting cuttings This process also allows for a process called grafting, where two different plant cuttings (root and shoot) can be combined to produce a new plant

SEXUAL REPRODUCTION Basic process of Meiosis (two gamete cells fusing to form a zygote) Creates genetic diversity (essential for the survival of a species) Not as fast as A-sexual reproduction

Sexual reproduction in Uni Cellular organisms Common misunderstanding that single celled organisms reproduce only A-sexually If this were the case we would not see the amazing diversity of single celled organisms Several protozoan have the ability to produce gametes Generally one gamete is larger and sedentary and one is smaller and mobile (much like in humans) Paramecium does not involve gamete production, rather an exchange of genetic material whilst lined up along side one another. This process is called CONJUGATION