Download Section: Sexual Reproduction

Section: Sexual Reproduction
Key Words: gene, DNA, reproduction, sexual reproduction, sperm, egg, gamete, pollen, pollination,
stigma, anther, ovum, chromosome
Essential Questions:
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How are gametes involved in sexual reproduction?
How do plants reproduce sexually?
How does sexual reproduction lead to species diversity?
Sexual reproduction
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formation of a diploid cell
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joining of 2 haploid cells
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created by the process of meiosis
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cells that have half the number of chromosomes as the diploid
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normal human cell – 46 chromosomes
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human gamete cell – 23 chromosomes
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male human gamete (23) + female human
gamete (23) = normal human cell (46)
DNA – deoxyribonucleic acid
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Forms the strands called chromosomes
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Makes up “genes” – parts of the DNA strands that code
for a specific protein
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Phenotypes – physical traits
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Eye color
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Tongue-rolling
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Right hand/left hand
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Skin tone
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Hair color
Genotypes – genetic make up coding traits
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Dominate and recessive traits
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Homozygous (same) and heterozygous
(different)
“gametes”
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Sperm or egg (or ovum)
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combination of both parent’s traits
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offspring resembles both parents, rarely one
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combination varies with each offspring
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creates species diversity
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once fertilization occurs – mitosis allows for growth
Fertilization
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mechanisms differ among plant and animal kingdom
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animals
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males deposit gametes on or near the female gamete
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land – internally via copulation
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water – externally because of fluid environment
plants
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pollination – sexual reproduction among plants
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gymnosperms - “naked seed”
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angiosperms – “flowering plants”
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male gametes on anthers – pollen grains
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transported by wind, water, or animals
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female gamete is attached to stigma