Biochemistry Review

1. Biochemistry Review Make a table that organizes the following words: phosphodiester bonds peptide bonds glycosidic linkagesester linkages Polypeptides triacylglycerols polynucleotides polysaccharides monosaccharides nucleotides amino acids fatty acids Sugars proteins fats nucleic acids

2. Animal Development

3. “Man the seed, woman the incubator.”

4. Cell Differentiation • As a zygote divides, genes are expressed differently in each new cell • Expression is different due to: • Molecules in the egg cell • Signals from neighboring cells • Leads to CELL DIFFERENTIATION • Specialization in structure & function

5. Stages in Embryological Development • Fertilization • Sperm and egg combine • Cleavage • Cell division and multiplication • Gastrulation • Development of embryo • Organogenesis • Growth of organs

6. Fertilization - Sea Urchin • ACROSOMAL REACTION • Acrosome releases hydrolytic enzymes which digest the jelly coat of the egg • Actin filament protrude from sperm head and join to receptors on the egg plasma membrane • Sperm and egg membranes fuse and trigger depolarization; sperm nucleus enters egg • Depolarization prevents polyspermy • FAST – BLOCK to POLYSPERMY

8. What mechanisms are there in the acrosomal reaction that prevent the wrong sperm from fertilizing an egg of another species?Why is this especially important in aquatic environments?

9. Fertilization – Sea Urchin • CORTICAL REACTION • Depolarization is only a temporary sperm block • Vesicles below egg membrane release cortical granules • Granules cause egg to form FERTILIZATION ENVELOPE • Envelope block entry of other sperm • SLOW – BLOCK TO POLYSPERMY

10. Calcium ions cause release of granules from vesicles

11. Fertilization - Mammals • Mammalian egg covered with FOLLICLE CELLS • Sperm travels through these cells to reach the ZONA PELLUCIDA, or external matrix of the egg • Part of the zona pellucida is receptor for sperm which triggers the acrosomal reflex • Fusion of sperm and egg triggers chemical changes which act at slow block to polyspermy • No fast-block • Whole sperm enters the egg, membranes dissolve and chromosomes undergo mitosis

13. Stages of Development Zygote Morula Blastula Gastrula

14. Cleavage • Succession of rapid cell divisions • No overall growth just creation of many smaller cells

15. Cleavage - Amphibians • Cells continue to divide until they form a BLASTULA • Hollow ball of cells • Space inside of blastua is filled with fluid and called a BLASTOCOEL

16. Cleavage - Amphibians • Egg has “sides” or POLES • Stored nutrient side = YOLK = VEGETAL HEMISPHERE • Developing animal = ANIMAL HEMISPHERE • Location of poles determines anterior/posterior region of animal

17. Cleavage - Amphibians • When sperm enters the egg, animal pole moves toward point of entry • Causes formation of GRAY CRESCENT • Mixture of animal and vegetal poles • Marks dorsal side of embryo

18. Cleavage – Other animals • HOLOBLASTIC CLEAVAGE • “Total cleavage” • Egg has little yolk; embryo receives nutrients from mother • Central blastocoel • Clevage furrow passes all the way through the cells • Humans, placental mammals, marsupials

19. Cleavage – Other animals • MEROBLASTIC CLEAVAGE • Lots of yolk prevents cleavage furrow from completely forming • Birds, fish, insects, reptiles

21. Gastrulation • Groups of cells begin to move to new places which will allow for the formation of tissues and organs • Establishes cell layers • Diploblastic, triploblastic

22. Gastrulation • GERM LAYERS – tissue layers formed by gastrulation • ECTODERM • ENDODERM • MESODERM • All will form the organs of the adult animal

23. Gastrulation Animation

24. Endo,Meso orEcto? • Muscles • Epidermis • Nervous system • Reproductive systems • Excretory system • Liver • Thymus • Skeletal system • Circulatory system • Cornea • Pancreas • Lining of digestive tract • Dermis of skin • Muscles • Epidermis • Nervous system • Reproductive systems • Excretory system • Liver • Thymus • Skeletal system • Circulatory system • Cornea • Pancreas • Lining of digestive tract • Dermis of skin

25. Formation of Nervous System • Begins with formation of NOTOCORD • Eventually becomes vertebral column in vertebrates • Thickend area at top of notocord called NEURAL PLATE is first spot of nervous system development • Neural folds close forming the neural tube • Neural tube eventually becomes brain and spinal cord

27. Amniotic Development • In an egg or in a womb • EXTRAEMBRYONIC MEMBRANES • CHORION • Gas exchange • AMNION • Protective surrounding membrane • YOLK SAC • Provides nutrients • ALLANTOIS • Waste disposal and gas exchange

29. Human Development • No polarity • No yolk • Morula implants into uterine • Outer layer of cells called a TROPHOBLAST

30. Human Development • Trophoblast begins to secrete Human Chorionic Gonadotropin (hCG) • Prevents disintegration of corpus luteum and shedding of endometrium

31. Placental Development • As the embryo grows, so does the PLACENTA • Organs that functions in gas, nutrient, and waste exchange between the embryo and mother

32. Placental Development • Placenta produces progesterone and estrogen • Prevents more follicles from maturing • Maintains uterine lining • UMBILICAL CORDcontains arteries and veins which transports materials from fetus