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sexual and asexual reproduction


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sexual and asexual reproduction

  1. 1. My presentation in science
  2. 2. reproduction asexual • involves only • offspring genetically identical parenthetical to parent • involves regular body cells • its quick sexual • Sexual Reproduction • involves 2 parents • offspring genetic mix of both parents • involves specialized sex cells
  3. 3. budding  budding, Hydra [Credit: Roman Vishniac Archive, International Canter of Photography, New York, courtesy of Mara Vishniac Kohn]in biology, a form of asexual reproduction in which a new individual develops from some generative anatomical point of the parent organism. In some species buds may be produced from almost any point of the body, but in many cases budding is restricted to specialized areas. The initial protuberance of proliferating cytoplasm or cells, the bud, eventually develops into an organism duplicating the parent. The new individual may separate to exist independently, or the buds may remain attached, forming aggregates or colonies. Budding is characteristic of a few unicellular organisms (e.g., certain bacteria, yeasts, and protozoans);
  4. 4. Spore formation  First off, you might think of a bacterial spore roughly as a mummified bacterium. The spore has a hard protective coating that encases the key parts of the bacterium— think of this coating as the sarcophagus that protects a mummy. The spore also has layers of protective membranes, sort of like the wrappings around a mummy. Within these membranes and the hard coating, the dormant bacterium is able to survive for weeks, even years, through drought, heat and even radiation. When conditions become more favourable again—when there’s more water or more food available—the bacterium "comes to life" again, transforming from a spore back to a cell. Some bacterial spores have possibly been revived after they lay underground for more than 250 million years!  Ok, so how do bacteria turn themselves into spores? First, the bacterium senses that its home or habitat is turning bad: food is becoming scarce or water is disappearing or the temperature is rising to uncomfortable levels. So it makes a copy of its chromosome, the string of DNA that carries all its genes.
  5. 5. Sexual and asexual reproduction of a plant.
  6. 6. Sexual reproduction  Sexual reproduction is a process that creates a new organism by combining the genetic material of two organisms; it occurs both in eukaryotes[1][2] and in prokaryotes.[3] A key similarity between bacterial sex (bacterial conjugation) and eukaryotic sex is that DNA originating from two different individuals (parents) join up so that homologous sequences are aligned with each other, and this is followed by exchange of genetic information (a process called genetic recombination). After the new recombinant chromosome is formed, it is passed on to progeny.  On the other hand, bacterial conjugation, a type of transfer of DNA between two bacteria, is often regarded as equivalent of sexual reproduction because the mechanics are similar.[4] This is because bacterial conjugation is controlled by plasmid genes that are adapted for spreading copies of the plasmid between bacteria. The infrequent integration of a plasmid into a host bacterial chromosome, and the subsequent transfer of a part of the host chromosome to another cell do not appear to be bacterial adaptations.[3][5]
  7. 7. Asexual reproduction  Any reproductive process that does not involve meiosis or syngamy is said to be asexual, or vegetative. The absence of syngamy means that such an event can occur in the sporophyte generation or the gametophyte stage. Because of the lack of new genetic material, an organism clones itself through this process and makes genetically identical organisms. This can be advantageous in some circumstances, but deleterious in others, depending on how the makeup of the plant suits its ecosystem. There are a few major ways in which plants asexually reproduce in their life cycles to secure future generations.  New plants can grow by the separation of parts of the original plant. When fragmentation, or division, occurs, an offspring is created by the breakup of a single part of the plant. By planting parts of the tuber of a potato, one can create new organisms with the same genetic makeup. When weeds are broken apart, they can regrow from each fragmented underground stem. In Merchantman, fragmentation of the phallus gives rise to vegetative reproduction. When rain drops hit the plants, these structures are splashed out and may germinate into completely new plants. With these vegetative structures, many clones can be formed from one original parent. Bulbs and Rhizomes are also examples of asexual reproduction.
  8. 8. Advantage and disadvantage asexual Advantage: No mate needed. Many offspring produced quickly Disadvantage: No variation in the offspring. sexual Advantage: Genetic variation in the offspring. Disadvantage: Requires both sexes to participate.
  9. 9. Thank you for listening  Prepared by aira s. domalaon  7-descartes