Chapter 49 & 50 Outline

Chapter 49 & 50 Outline - Reproduction Chapter 49...

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Reproduction Chapter 49 Learning Objective 1 Compare the benefits of asexual and sexual reproduction Describe each mode of reproduction, giving specific examples Asexual Reproduction Single parent genes of offspring identical to parent’s (except for mutations) Benefits energy efficient most successful in a stable environment Don’t have to search for a mate Genetic stability Types of Asexual Reproduction Budding Small part of parent’s body grows, detaches e.g. flatworms and annelids Fragmentation parent’s body breaks into pieces each piece can develop into new animal e.g. sea stars Parthenogenesis unfertilized egg develops into adult (haploid) Rapid reproduction Insects, reptiles, fish Budding (Fig 49-1) Sexual Reproduction Fusion of two types of gametes ( egg and sperm ) produces offspring Egg is large and nonmotile; sperm small and flagellate Fusion leads to a fertilized egg ( zygote ) Benefits genetic variety adaptive in unstable, changing environment Strong survivors Selects against and removes harmful mutations Fertilization
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External fertilization mating partners release eggs and sperm into water simultaneously e.g. spawning frogs Internal fertilization male delivers sperm into female’s body Fusion inside body e.g. terrestrial animals, sharks, mammals External and Internal Fertilization Fig 49-2 Hermaphroditism Single individual produces both eggs and sperm e.g. tapeworm, earthworm, tunicates Typically two individuals come together and swop each others sperm KEY CONCEPTS Most animals reproduce sexually by fusion of sperm and egg, but some animals reproduce asexually and some can reproduce either way, depending on conditions Learning Objective 2 Describe the structure and function of each organ of the human male reproductive system Male Reproductive System (Fig 49-3) Testes 1 Contained i n the scrotum Paired male gonads Serves as a cooling unit maintaining sperm below body temperature Connected to pelvic cavity by inguinal canals: straining can cause loop of intestine into scrotum = inguinal hernia) Contain seminiferous tubules Hollow tubes where spermatogenesis (sperm production) takes place Spermatogonia (undifferentiated cells in the walls of the tubules) Spermatogenesis Fig 49-5 Sperm Structure (Fig 49-6) Conducting Ducts Sperm moves from seminiferous tubules to epididymis and vas deferens sperm maturation and storage Ejaculation of sperm from vas deferens to ejaculatory duct into urethra (through penis) Release from body Accessory Glands
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Sperm mix with semen in the conducting tubes: about 200 million sperm per ejaculation Mix with secretions from seminal vesicles fructose (energy for sperm) and prostaglandins (stimulate contractions of uterus) And prostate gland Alkaline fluid containing Ca2+, citric acid and enzymes (neutralizes acidity in
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This note was uploaded on 10/08/2010 for the course BIO 380 taught by Professor Martin during the Spring '10 term at Rutgers.

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Chapter 49 & 50 Outline - Reproduction Chapter 49...

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