Reproduction An Overview

Reproduction Reproduction is the process by which an organism produces others of its same kind It is the way a species is continued May be either sexual or asexual depending on the species

Comparison of Asexual and Sexual Reproduction Asexual Reproduction One parent Genetically identical to parent Cell copies or clones itself and splits off from a parent Common in simple organisms such as bacteria and ferns Sexual Reproduction Two parents Offspring similar to parents, but not genetically identical Two gametes fuse nuclei to form a zygote Common in complex organisms such as vertebrates

Advantages/Disadvantages Asexual Advantage: – Numerous offspring with little effort or time used Disadvantage: – Only source of diversity is mutation (a mistake in copying the DNA) – Population is uniform Sexual Advantages: – Greater diversity in offspring – Species can evolve Disadvantage: – Requires more time and effort to reproduce

Asexual Reproduction: Genetically Identical Offspring Budding Regeneration Parthenogenesis … Cloning???

Binary Fission… most common form of reproduction in prokaryotes and occurs in some single- celled eukaryotes

Budding… New Organisms Arise as an Outgrowth from the Parent Organism Seen Mostly in Marine Animals – Examples Include; Hydra, Yeast, Sponges, Corals and Jellyfish… Coral Polyp Photo courtesy Jeffrey N. Jeffords

Fragmentation and 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)

Parthenogenesis… Offspring can arise from unfertilized eggs. Includes some Fish, Reptiles, Amphibians and Aphids. Most of these species can switch between Sexual and Asexual Reproduction. (depending on conditions) Hawaiipics/Rhampho.jpg vocationType=imageResults&query=photos +of+parthenogenic+species&img %20Fall% %20Biology%20and% 20Evolution%20of%20Sex/Gynogenesis.Poec ilia.pdf

Examples of Sexual Reproduction

Examples of Sexual Reproduction--Pollination

Examples of Sexual Reproduction

Sexual Reproduction Cellular Level Where Is the Information for Heredity Stored?

Sexual Reproduction Cellular Level The key to the diversity we see in organisms that reproduce sexually is the special form of cell division that takes place ONLY in the male and female reproductive organs Results in gametes (sex cells)that each have half of the chromosomes necessary to make an organism The name of this process is meiosis It occurs in the ovaries and testes in humans

Sexual Reproduction Organism Level Fertilization- Gametes (such as egg and sperm) from two parents fuse to form a zygote (offspring) Male and female human body cells contain 46 chromosomes in 23 pairs Ovaries produce egg cells that each contain 23 chromosomes Testes produce sperm cells that each contain 23 chromosomes 23 46

Sexual Reproduction Species Level Allows for greater genetic variability in offspring Allows for diversity in a population Allow the ability to evolve Why is that an important advantage for the species?