Chapter 12: Reproduction

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Chapter 12 Reproduction

• 12.1 12.2

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12.1 Asexual Reproduction

• Process of reproduction by a single parent ?
  produces GENETICALLY IDENTICAL OFFSPRING
• Clones the offspring of asexual reproduction
  (genetically identical)

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12.1 Asexual Reproduction

• Examples
• Binary fission occurs in Prokaryotes produces
  2 identical cells (cell divides into 2 after its
  DNA has been
• copied)

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12.1 Asexual Reproduction

• Mitotic division Happens in Unicellular
  eukaryotes, such as a Paramecium, which creates 2
  new identical organisms by dividing through
  mitosis

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12.1 Asexual Reproduction

• Budding In Hydra a bud breaks away from
  parent to live independently

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12.1 Asexual Reproduction

• Fragmentation In Planeria (flat worms), an
  organism breaks into pieces and each fragment
  turns into a new organism

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12.1 Asexual Reproduction

• Vegetative Reproduction (Propagation) In certain
  plants, like grasses, runners are used to help
  them spread quickly
• This can be done artificially as well.

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12.1 Asexual Reproduction

• Artificial Vegetative Reproduction
• Horticulturalists farmers will use cuttings
  from a parent plant to create identical plants

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12.1 Asexual Reproduction

• Artificial Vegetative Reproduction
• In grafting, 2 plants are used to develop a new
  plant that has the desired characteristics

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Asexual Reproduction

• Advantages
• Happens quickly
• Requires less energy
• No need to find a mate
• Offspring usually well-adapted because parents
  are able to reproduce

• Disadvantages
• NO genetic variation (susceptible to diseases,
  environmental changes, predators)
• Only 1 parent for offspring (sometimes parent
  disappears completely binary fission)

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Chromosomes

• What are chromosomes?
• What do living things need them for?

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12.2 Chromosome Number

• Every species has a characteristic number of
  chromosomes
• Examples
• Prokaryotes 1 major chromosome
• Humans 46 chromosomes
• Turkeys 82 chromosomes

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12.2 Chromosome Number

• In sexually reproducing organisms
• The typical chromosome number occurs in pairs
• Ex humans have 46 chromosomes 23 pairs of
  chromosomes
• Source of pairs each parent provides one
  chromosome of the pair

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12.2 Chromosome Number
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12.2 Chromosome Number

• Diploid (2n) a cell with the double set of
  chromosomes
• Diploid human cell 46 chromosomes
• Haploid (n) a cell with one set of chromosomes
• Haploid human cell 23 chromosomes
• What kind of cells would only have ½ the number
  of chromosomes?

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12.2 Chromosome Number

• In Organisms that reproduce sexually
• Sex cells (gametes) must be haploid
• Why?
• Two gametes fuse together during fertilization,
  each must be haploid so that the resulting zygote
  is diploid

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12.2 Chromosome Number

• Gametes Reproduction
• Males sperm
• Females ovum (egg)
• Fertilization sperm egg (haploid) nuclei
  fuse, resulting in a zygote (diploid)
• Zygote the diploid cell that results from
  fertilization

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12.2 Chromosome Number

• Meiosis process that produces haploid gametes
  (sperm eggs)
• It can also produce spores haploid cells that
  can produce haploid organisms