Why Sex?: http://www.youtube.com/watch?v=gRpEt61XM4M&safe=active Sexual Reproduction Why Sex?: http://www.youtube.com/watch?v=gRpEt61XM4M&safe=active

Monoploid gametes (n) are produced by meiosis or “_____________” with half the chromosomal material as the parent cell ________________________________ takes place resulting in greater genetic variation

________________ (egg/sperm) come from 2 separate parents. Gametes fuse together during _________________ creating a _________ (diploid 2n)

Advantages of Sexual Reproduction: Offspring genetically _________from parents This variation means that even if changes in environment occur some offspring may survive (__________________)

Sexual Reproduction in Simple Organisms Conjugation: often found between ____ ___________________ like bacteria Bridge of cytoplasm between cells allows exchange of genetic material Can occur even though the species normally reproduces asexually through binary fission

Sexual Reproduction in Animals Usually involves two different sexes Gametes develop in specialized organs (_____________) Ovaries produce eggs (n) (ova) Usually larger, round and ______________ Often contain stored food in the form of yolk Testes produce sperm (n) Usually motile Has a head (containing DNA), middle (containing Mitochondria) and tail (flagellum) Head has _____________________, helps penetrate egg

Gametogenesis (meiotic division) Oogenesis: one primary sex cell develops into _________________and several __________

Gametogenesis (meiotic division) Spermatogenesis: one primary sex cell develops into _________________

Hermaphrodites Have _________________________ Usually found in animals that _____________ and it may be hard to locate mates Two animals meet and fertilize each other Ex: earthworm

Fertilization Monoploid sperm (n) & Monoploid egg (n) come together to make ____________ zygote (2n) All _______________________ in zygote come from egg Membrane forms around egg after fertilization preventing other sperm from entering

External Fertilization _______________ outside body of female. Requires ______________ for sperm to swim to egg Often occurs with aquatic animals ___________ numbers of eggs and sperm are released to increase chance of fertilization Timing of release controlled by hormones and sexual signaling Ex: _______________& _______

Internal Fertilization http://www.youtube.com/watch?v=bRKdTAzPBv0&safe=active http://www.united-academics.org/magazine/earth-environment/top-ten-weirdest-animal-penises/ Fusion of gametes occurs within moist __________ environment of female’s reproductive tract Occurs in ________________________________ terrestrial vertebrates Allowed for a way for animals to evolve to live on land! Requires specialized sex organ to carry sperm from males body to females (____________) Seminal fluid (semen) provides _______________ for sperm to swim

Internal Fertilization After fertilization the embryo is either: enclosed in a ____________ and is ejected to develop outside of females body (oviparous) ex: chicken egg remains and develops in a special __________ of females body ex: human uterus

Advantages of Internal Fertilization: Gametes not _____________ in environment where they could be destroyed Chances of fertilization _____________ Don’t need __________________________ they require a huge amount of energy to make! Still have ________________ of sperm released to guarantee fertilization takes place

Parthenogenisis Development of an _______________ into an adult animal without fusion with sperm Ex: many insects including bees, wasps, ants, also some lizards In bees an unfertilized egg will become a male drone and fertilized eggs become female workers or queens

Early Embryonic Development Cleavage: series of ____________ cell divisions of zygote # of cells increases but growth _____________ Morula: ___________________ Blastula:

Three cell layers form: Gastrulation: Cells of blastula _____________________ forming gastrula Opening is called the blastopore This later becomes the opening to digestive system Three cell layers form: ______________, _________________ & ______________

Growth & Differentiation of Cells Three cell layers of gastrula differentiate into different tissues of body (___________________) Ectoderm (outer layer) _______________________________________ Mesoderm (middle layer) Endoderm (inner layer)

Differentiation Differentiation occurs because: different sections of DNA called genes _____________________ in different cells, controlling what type of cell it will become _____________________________ between adjoining cells can also influence cell type and development http://education-portal.com/academy/lesson/overview-of-animal-reproduction-and-development.html

Development & Growth of Embryo Development is the process by which the embryo becomes the organism. An embryo needs: protection from elements a way to get __________________ regulate temperature get rid of it’s __________________

External Development In Water: nourishment comes from ______________, gets oxygen from water, wastes diffuse into water Requires little or no ____________________ Some animals guard eggs or fan water currents to provide more oxygen

On Land Need large egg with yolk (nourishment) protected by a shell A self sustained watery environment ____________________ allows oxygen in and carbon dioxide out Ex: Reptiles, Birds and Monotremes (Ex: platypus)

Structure of a Typical Egg Hard porous shell containing special membranes Chorion: outermost membrane lining inside of shell _____________________ with external environment Allantois: exchange of ______________ take place Metabolic wastes (like uric acid )collect here Site for ____________________________ Amniotic Sac: fluid filled sac surrounding embryo ________________________ from shock Yolk Sac: Source of ____________ for embryo Has blood vessels to carry food to embryo

Internal Development Mammals: Internal fertilization Embryo develops in ________ or ______________ When born offspring receives nourishment from mother from __________________ Only _______________ are produced at a time

Placental Mammals: Embryo becomes implanted in the _________________ _____________ that serves as a organ for exchange of _________, _______ and ________________ between embryo’s blood and mothers blood Provides embryo with site for: __________, ____________ and __________________ Embryo becomes attached to a placenta by an __________________ No direct mixing of blood

Non Placental Mammals Pouched: Egg Laying: Marsupials (like Kangaroo) Egg Laying: _____________ (Echidna), _____________________ Embryos are born _______________________. Must complete development in a pouch. No _____________________ of young in uterus Crawls into pouch, attaches ________________ to complete development Baby Echidna: http://www.youtube.com/watch?v=ZXEC1Qx4cJg&safe=active Kangaroo Giving Birth http://www.youtube.com/watch?v=2lCKc8tURtc&safe=active

Try These Questions What is the function of the placenta? Why do fish produce more eggs than birds? What advantage is it to have an egg shell on dry land? How do the eggs that develop in water obtain nourishment and oxygen? What happens during gastrulation?