Cell Division And Reproduction We learned that cells division occurs for healing, repair and growth. But cell division is also the process that allows reproduction, and therefore allows species to continue. Organisms of all species reproduce. There are two types of reproduction: asexual and sexual

Asexual Reproduction: –A single organism produces offspring (young) with identical genetic information. –Most are single-celled organisms such as bacteria –Some are multicellular organisms such as fungi and some plants

Sexual Reproduction: –Genetic information from two cells is combined to produce a new organism. –Usually occurs when two specialized cells (an egg cell and a sperm cell) join to form a zygote (fertilized egg) which then develops into a new organism.

Asexual Reproduction Formation of a new individual that has identical genetic information to its parent. Review Five-Kingdom Classification System There are many methods of asexual reproduction and in all cases, only one parent is required to produce offspring. Methods: binary fission, fragmentation, budding, spore formation and vegetation reproduction.

ASEXUAL REPRODUCTION IN BACTERIA Kingdom: Monera Description: Unicellular organisms that do not contain a true nucleus. (Prokaryotes) Type of Asexual Reproduction: Binary Fission Read: Pause and Reflect p.29 and handout: Stretch your Mind Activity

ASEXUAL REPRODUCTION IN AMOEBA Kingdom: Protista Description: Unicellular organisms that do contain a true nucleus. How does it work: Mitotic cell division in these unicellular organisms result in the formation of two identical offspring. Protists are important because they form the basis of many food chains and because they are responsible for many diseases that affect humans.

ASEXUAL REPRODUCTION IN FUNGI Kingdom: Fungi Description: Moulds, yeast and mushrooms. The bodies of these organisms are composed of many thin filaments called hyphae. The hyphae grow over the surface of and into the bodies of other organisms to obtain food. Three types of Asexual Reproduction: 1.Fragmentation 2.Budding 3.Spores

ASEXUAL REPRODUCTION IN FUNGI 1.FRAGMENTATION: How does it work: A small piece, or fragment, breaks away from the main mass of hyphae and grows into a new individual. What must the fragment contain to enable it to develop into a new organism identical to its parent? 2.BUDDING: How does it work: Occurs in yeast : unicellular fungi used for making bread and alcohol products First a copy of the nucleus is made Next, a tiny bud begins to form on the cell wall This bud containing the new nucleus, continues to grow larger Eventually breaks away to become a single, independent cell

ASEXUAL REPRODUCTION IN FUNGI 3. SPORE: How does it work: Occurs in moulds such as Rhizopus Moulds produce spores, which is a reproductive cell that can grow into a new individual through mitotic cell division. Spores are stored in a case called a sporangium When spores are mature, they take on a characteristic colour: black, yellow, blue or red

ASEXUAL REPRODUCTION IN ANIMALS Kingdom: Animalia Divided into two main groups: 1. Vertebrates (those with backbone) 2. Invertebrates (those without backbones) Description: Invertebrates: sponges, jellyfish, worms, shellfish and insects. (97% of all animal species) Many invertebrates can reproduce asexually to form one or more identical offspring from a single parent.

How does it work: Planaria –Type of flatworm –Reproduce asexually by dividing in two and regenerating the parts they are missing –The part that retains the head will grow a new tail –The part with the tail will grow a new head –Planaria will also regenerate injured body parts Sponges and Hydras –Reproduce asexually by budding –A cell, usually near the base of these organisms, undergoes mitosis and cell division repeatedly to produce a group of new cells, or a bud. –Eventually, when the bud completes its development, it detaches and becomes independent