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REVIEW. How many different donors of chromosomes and genes are required for sexual reproduction? Name three living species that use sexual reproduction? What percentage of chromosomes and genes does an offspring receive from their father?. What is asexual reproduction?.

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  1. REVIEW • How many different donors of chromosomes and genes are required for sexual reproduction? • Name three living species that use sexual reproduction? • What percentage of chromosomes and genes does an offspring receive from their father?

  2. What is asexual reproduction? • Reproduction in which only 1 parent contributes genetic information, this creates offspring that are genetically identical (exact copies) of the parent. • Generally used by less complex organisms. • Does not provide any genetic variation. • Sexually reproducing organisms tend to very little if any at all parental care. • Because, they are able to produce so many offspring.

  3. Fission • Single celled organisms, such as paramecium and bacteria, which reproduce by splitting in two. This is often the only mode of reproduction for these organisms. • EXAMPLE: Bacteria: A single-celled organism that has no nuclei or cell walls and reproduce by splitting in two. • http://youtu.be/DY9DNWcqxI4

  4. Fragmentation • Some animals can grow from a separate piece of parent animal. This happens in only the simplest animals, such as some flatworms. These animals may also reproduce sexually. • EXAMPLE: Some flatworms can grow by cell division from a fragmented section of its body.

  5. Vegetative propagation • New plants can be produced from sections of parent plants that are cut off. Cambium cells from stems, roots and leaves of a parent plant can take root and sprout. New plants reproduced in this way are genetically identical to the parent plant. We see this in spider plants and willow trees, for example. • EXAMPLE: Strawberries reproduce new plants by the division of cells from runners or roots. Strawberries also reproduce sexually • Vegetative propagation occurs in a variety of ways. • http://youtu.be/NfPP2CQGuC0

  6. Budding • Cell division produces a bud. As the bud grows, it forms an identical copy of its parent, then separates from the parent and becomes independent. An example is a hydra. These organisms may also reproduce sexually. The "choice" between sexual and asexual reproduction is often mediated by environmental conditions. • EXAMPLE: Hydra: Cell division forms a bud that is an identical copy of its single parent that separates from the parent and becomes independent. • http://youtu.be/JZLHJZZZS-Y

  7. Parthenogenesis • Some animals may produce eggs that develop directly into offspring without fertilization. Common examples occur in insects, reptiles and fishes. Often, these organisms may also reproduce sexually. The "choice" between sexual and asexual reproduction is typically mediated by environmental conditions. • EXAMPLE: A female whiptail lizard may produce eggs that develop into genetically identical versions of itself. In some species, there are entire clonal populations of this lizard. Most whiptail lizard species do reproduce sexually, though • http://youtu.be/_-NudTF3if4

  8. ADVANTAGES OF ASEXUAL REPRODUCTION? 1. Large numbers of offspring are reproduced very quickly from only one parent when conditions are favorable. 2. Large colonies can form that can out-complete other organisms for nutrients and water.  3. Large number of organisms mean that species may survive when conditions or the number of predators change.  4. Energy is not required to find a mate.

  9. DISADVANTAGES OF ASEXUAL REPRODUCTION? 1. Offspring are genetic clones. A negative mutation can make asexually produced organisms susceptible to disease and can destroy large numbers of offspring. 2. Some methods of asexual reproduction produce offspring that are close together and complete for food and space. 3. Unfavorable conditions such as extreme temperatures can wipe out entire colonies.

  10. Resources • Ohio.gov department of education. 2011. Accessed at URL: http://dnet01.ode.state.oh.us/IMS.ItemDetails/LessonDetail.aspx?id=0907f84c805317b8 • Answers.com.2011. Accessed at URL: http://wiki.answers.com/Q/State_3_advantages_and_3_disadvantages_of_asexual_reproduction

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