Sexual Reproduction and Fertilization

☺Sexual Reproduction— offspring are formed when genetic information from more than one parent combines It requires two parents: a male and a female

☺Female: sex cells called EGGS ☺Male: sex cells called SPERM ☺When an egg’s nucleus and a sperm’s nucleus join, a fertilized egg is formed…a ZYGOTE. ☺That process is called FERTILIZATION.

☺Genetic information is found in GENES. ☺Genes are located on CHROMOSOMES. ☺Chromosomes are made of proteins and DNA.

During fertilization, the egg and sperm each contribute chromosomes to the zygote. The new organism grows into a unique individual. It is not identical to either of its parents. ☺The combination of genes during sexual reproduction allows for variation within a population.

☺Advantage of Sexual Reproduction: It allows a population to adapt to changes in the environment over time.

Fertilization can happen either outside or inside the female’s body. ☺External Fertilization-union of sex cells outside the bodies of the parents It has to have a moist environment so the eggs won’t dry out. EX: Angelfish, Frogs

☺Internal Fertilization-an egg and sperm join inside the female’s body This allows for better protection of the fertilized eggs. EX: Reptiles, birds, mammals, some fish

Mammals: Monotreme—lay eggs Ex: Platypuses Marsupial—give birth to partially developed live young Ex: Opossum, Kangaroo, Koala Placental Mammal—nourished inside mother’s body before birth Ex: Humans, Bats, Armadillos

Plug it in…Plug it in!!! 1.What are female sex cells called? 2.What are male sex cells called? 3.What is a fertilized egg called? 4.What is an advantage of sexual reproduction? 5.What is the difference between external and internal fertilization?