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REPRODUCTION ASEXUAL REPRODUCTION Reproduction from one organism. The cell division is mitosis. The genetic trats are same with the parent organism. Doesn’t effect evolution or variation. Seen in primitive organisms Only mutations can form variations Monoploid (n) or diploid(2n) organisms can be formed Reproduce rapidly Mitosis Mitosis is important in: Repair and regeneration. Growth Mitosis is a fundamental process for life. During mitosis, a cell duplicates all of its contents, including its chromosomes, and splits to form two identical daughter cells. As a result of the mitosis: 2 new cells are formed New cells have same genetic material and chromosome number with mother cell. The genetic material and chromosome number of the new cells are same. Mitosis http://www.whfreeman.com/thelifewire6e/content/ch09/ani0901mov1.html http://www.sumanasinc.com/webcontent/anisamples/biology/biology.html Interphase: Resting period of the cell. Cell carries out normal activities. Prophase: DNA of the cell replicates itself. 2 sister chromatids are formed Metaphase: Chromosomes with sister chromatids stay in the middle of the cell (equator). Anaphase: Sister chromatids separate from each other and go to the opposite poles. Telophase: Chromatids reach to the poles and nuclear membrane is formed Asexual reproduction types 1. Division(binary fission) 2. Budding Young organism is formed from the body of the existing organism. Yeast cells, hydra 3. Sporing ( fungi, algae, plasmodium,, fern, moss) Spores(n) gametophyte plant(monoploid) gametes fertilization diploid plant (2n) (meiosis) Moss, ferns, fungi and plasmodium Spores are different from gametes. They are seen in asexual reproduction. Forms new individual by germination. 4. Vegetative reproduction The parent plant grows runners and forms new plant. They are typically same. Strawberry, onion, violet, potato 5. REGENERATION The parts which are cut off the plant or animal can form a new organism or an organ. Starfish, earthworm, lizard. But some animals can not produce new organism just form the organ or heal the wound. SEXUAL REPRODUCTION Reproduction from 2 parents. (one forms sperm, the other forms egg) Major Division is meiosis and the major process is fertilization. Newly formed organisms have new traits different from the parents and the other new organisms. Sexual reproduction enhance evolution and variation. These variations help organisms to survive better. Can be seen in higher organisms like animals and plants. The reasons for the genetic variations are: meiosis (crossing over, chromosomal lining in the metaphase) , fertilization and mutations. Newly formed organisms are diploid(2n) It is a long and slow process. Meiosis http://www.sumanasinc.com/webcontent/anisamples/majorsbiology/meiosis.html Meiosis is important in: formation of gametes (sperm, egg) reducing chromosome number genetic variation As a result of the meiosis: 4 new cells are formed New cells can have different genetic makeup from the mother cell New cells have half of the chromosome number of the mother cell.(n) The genetic makeup of the new cells can be different from each other. Meiosis http://www.whfreeman.com/thelifewire6e/con_index.htm?09 Prophase I: DNA replicates itself and forms a new DNA molecule. Homologous chromosomes exchange genes (crossing over) Prophase II: The chromosomes Metaphase I: Homologous chromosomes become shorter and thicker. (tetrad) line up in the middle of the cell(equator).Metaphase II: Spindle fibers attach to Spindle fibers attach to the chromosomes. the chromatids of the chromosomes. Anaphase I: Homologous chromosomes Anaphase II: Sister chromatids of the separate from eachother and go to the opposite chromosomes are separated and go to poles. the opposite poles of the cells. Telophase I: Chromosomes reach to the Telophase II: Totally 4 cells are formed. opposite poles. Two cells are formed . he Each cell can have a different genetic chromosome number is reduced by meiosis I. make up and half of chromosome number Mitosis and meiosis MITOSIS MEIOSIS 1. takes place in body cells. 1. takes place in germ cells and forms sex cells. 2. No crossing over (gene 2. crossing over can happen. Exchange) 3. It has 1 cycle of the phases 3. It has 2 cycle of phases(2 (1 division) division) 4. Produces 2 cells 4. Produces 4 cells 5. newly formed cells have 5. Newly formed cells have the same chromosome the half of the number of the parent cell chromosome number of the parent cell 6. The genetic make up of the 6. The genetic make up of the newly formed cells are newly formed cells can be same with each other and different from each other with the parent cell and from the parent cell ISOGAMY HETEROGAMY 2 Gametes of the same 2 gametes of different 2 gametes wqith 2 morphological morphological gametes different structures structure unite. unite. There is a unite. The sizes of the structural difference gametes are very algae between sperm and egg different from each but not too much. other. human Algae, fungi SPECIAL REPRODUCTION TYPES 1. CONJUGATION This process is seen in bacteria, paramecium and green algae. 2 individuals exchange genetic material with each other. Most of the time DNA is not exchanged , instead plasmid which is a small part of DNA found in cytoplasm is exchanged. In that way organisms can gain new traits from the other organism. 2. PARTHENOGENESIS It is the formation of a new organism from the unfertilized egg. Male bee (n) Queen bee(2n) Mitosis Meiosis Sperm(n) Egg(n) parthenogenesis Female bee(2n) Male bee(n) Queen bee(2n) Worker bee(2n) 3. HERMAPHRODITISM Some organisms can carry both male and female reproductive system and organs. This process is called hermaphroditism. Earth worms, most of the plants are hermaphrodites. 3. HERMAPHRODITISM Some organisms can carry both male and female reproductive system and organs. This process is called hermaphroditism. Earth worms, most of the plants are hermaphrodites. Hermaphroditism causes variation but it is not as much as the variation in sexual reproduction. If same individual uses sperms and eggs from itself it will cause little variation. If gametes from 2 separate individuals fertilize they will cause more variation. Metagenesis n In some organisms sexual reproduction follows asexual reproduction. This is metagenesis. Moss Plazmodium (asexual in human, sexual 2n n in mosquito) Fern Plasmodium n (Mayoz) n n 2n 1. a female Anofele takes in gametes from the blood of human. 2. gametes are fertilized inside the mosquito’s intestine. Zygote forms. 3. Zygote forms spores by meiosis in mosquito. 4. Mosquito bites human and infects him with spores. 5. Spores reproduce asexually in blood and liver of human. And spores form gametes .
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