2. Do Now: Watch this clip and answer the following: 1.What took place in this sequence? 2.What cellular organelle must be far more prevalent in the sperm than the egg? Why? 3.Why do you think millions of sperm are released, if just one is needed to penetrate the egg? 4.What are the differences between the sperm and the egg? http://www.youtube.com/watch?v=65BV5dXXxzM&feature=related

3. Comparison of Egg & Sperm Egg (ovum)Sperm Can’t move Smaller Human sperm is.05mm Round Head, Middle Piece, Tail Contain flagella which allow them to swim Larger Human egg is.1mm

4. Fertilization & Zygote Formation

5. There must be a fluid medium so… sperm can swim to egg. Sperm’s head releases enzymes that dissolve opening through membrane of egg. Head enters and tail remains outside Mixing of genetic material from sperm and egg is called… Sperm Cell Nucleus (n) + Egg Cell Nucleus (n) = Zygote (2n Recombination

6. Location of Fertilization A.External Fertilization Sperm and egg join outside female’s body Only in animals that breed in water like.. fish & amphibians (frogs, toads, salamanders) Sperm swim through water to eggs Hazards: -Sperm may not meet eggs -Eggs may be eaten or may die due to pollution or temperature change. To overcome hazards, large numbers of sperm and eggs are released

7. B. Internal Fertilization Sperm and egg join inside female’s body Animals that reproduce on land like… birds, reptiles and mammals. Fewer eggs needed because there are less hazards. The eggs are well protected by female’s body.

8. Review!! External Fertilization Outside female’s body Fish and Amphibians Hazards: Sperm and eggs may not meet, eggs may be eaten or die to environmental changes… -Many eggs and sperm released Internal Fertilization Inside female’s body Land animals like reptiles, birds & mammals Less Hazards… Eggs well protected by female’s body… -Fewer egg released

9. Location of Development A.External Development in Water Embryo develops outside female’s body Nutrition from yolk in egg Takes place in fish & amphibians B.External Development on Land Outside female’s body Nutrition from yolk in egg Shell for protection Birds, Reptiles (snakes, alligators, turtles)

10. DO The Following… Read text page 775 on bird/reptile egg. You must sketch a picture of egg and label all parts. Also, describe the functions of the following : Albumen, Amnion, Yolk Sac, Allantois and Chorion.

11. Questions… 1.How is a bird egg and reptile egg different? 2.How does oxygen reach the embryo if there is a shell surrounding the embryo? 3.How does the embryo obtain nutrition? 4.What cushions the embryo? 5.Which structure serves as the embryo’s organ for gas exchange?

12. C. Internal Development 1. Placental Mammals Ex - Humans Embryo/fetus obtains nutrition from mother through placenta Umbilical Cord connects embryo/fetus to placenta Inside female’s body in uterus/womb Takes place in most mammals

13. 2. Non-placental Mammals Egg Laying Mammals Ex- Platypus- mammal that lays eggs. The embryo develops in an egg outside body. The egg contains much yolk. Young hatch and feed on milk from mother’s mammary glands. Pouched Mammals (Marsupials) Ex – Kangaroo No placenta Early development is in uterus and nutrition from yolk in egg. Young born immature and complete development in mother’s pouch getting milk from mammary glands

14. Parthenogenesis Development of an unfertilized egg into an adult without the fusion of sperm. Takes place in bees, wasps Ex: The queen bee of a hive lays fertilized and unfertilized eggs -The fertilized eggs (2n = 32) become the Female Workers. -The unfertilized eggs (n=16) become Male Drones

15. http://www.slate.com/id/2168092/www.slate.com/id/2168092