BIO 115 Reproduction 1 :Asexual and Sexual Process Lecture Notes

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Reproduction 1
Introduction to Animal Reproduction

A. Asexual Reproduction
● Single parent → 2+ offspring
○ Offspring are:
■ Identical
■ Clones




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● No meiosis
● No gamete fusion


Types of Asexual Reproduction
● Budding
○ One leads to two
○ Not symmetrical
● Fission
○ One leads to two
○ Symmetrical
● Fragmentation and regeneration
○ Cut organism into pieces and each piece grows into adult
● Parthenogenesis
○ Ploidy determines sex of offspring
■ Queen lays bunch of eggs
● Fertilized eggs (Diploid) = female offspring (sexual!)
● Unfertilized eggs (haploid) = male offspring (asexual)

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Advantages of Asexual Reproduction
● Rapid - many offspring in short time
● Don’t need to find a mate
○ Great if sessile (non motile) or have a low population density
● No sexually transmitted diseases



B. Sexual Reproduction
● Most animals reproduce sexually
● Reproduction involving production and fusion of gametes = crossing
● Sperm: small, motile, flagellated
● Egg (ovum): large, nonmotile, contains nutrients for embryo
● Involves fertilization: fusion of sperm + egg → zygote (2n)




Disadvantages of Sexual Reproduction
● “Reproductive cost” - only half of the population can actually reproduce




Advantage of Sexual Reproduction
● Promotes genetic diversity