Bio 10 Fertilization and Development Flashcards
Fertilization #1
Exocytosis occurs as the tip of the sperm reaches the jelly coat. Acrosome releases enzymes to digest.
Fertilization acrosomal reaction #2
Enzymes create a hole while growing actin filaments form from the acrosomal process. They bind to the egg cell receptors.
Fertilization block #3
Contact and fusion of sperm and egg occurs. Membrane voltage depolarizes causing a fast block to polyspermy.
Fertilization Cortical reaction #4
Ca++ is released from the Endo Reticulum. Cortical granules in the egg fuse with the plasma membrane. Sperm bind receptors are removed and fertilization envelope forms.
Slow block to polyspermy
In Fertilization #4 when the fertilization envelope forms.
Fertilization in Mammals
Generally internal. Egg releases progesterone which aids in motility. After fusion the entire sperm is taken into the egg.
Cleavage
Rapid period of mitosis. S and M phases. 4 cells is Blastomeres, then becomnig a solid ball, Morula.
Blastocoel
Fluid filled cavity forms within the morula and begins to hollow, becoming blastula.
Yolk distribution
Most important driving force that influences the cleavage pattern.
Two poles: Vegetal pole = high in yolk
Animal pole = low in yolk.
Gastrula
After cleavage, cell division slows and the process is called gastrulation. Results endo, meso, and ectoderm.
Z -> M -> B-> G
Zygote -> Morula -> Blastula -> Gastrula
Archenteron
New central cavity which becomes the primative gut during gastrulation. Opening of the archenteron is called the blastopore.
Blastopore
Opening of the gastrula that forms the mouth in protostomes and anus in deuterostomes.
Protostomes
Mollusks, arthropods, and annelids
Deuterostomes
Chordates and echinoderms
Mollusks
Snails, oysters, clams, squids, octopuses. Most have hard shells (CaCO3) and open circulatory system where fluid called hemolymph moves in cavities. Coelomates (have a body cavity).
Arthropods
Most successfull of all animal phyla and largest category. Insects, crustaceans, spiders, millipedes. Segments bodies, hard chitinous exosketelon. Jointed appendages, thousands of photoreceptors, open circulatory system.
Grasshoppers use Malpighian tubules to aid in metabolic waste removal.
Annelids
Worms. Closed circulatory system (blood moves through vessels). Segmentation. Setae to move, provides traction to crawl and burrow. Ganglia. Nephridia - functional unit of excretion, regs body fluid comp and vol.
Arthropods, annelids and mollusks are …….
Protostomes. Mouth forms first and anus forms second.
Echinoderms
Detuterostomes: anus first then mouth formation.
Sea stars, urchins, cucumbers.
Are radially symmetrical (Symmetrical in all directions).
Decentralized nervous system, no brain.
Unique to them is a water vascular system involved in locomotion, gas exchange, and nutrients.
Chordates
Fish, amphibians, birds, mammals, reptiles, tunicates, and lancelets.
Bilateral symmetry. Notochord (skeletal support). Dorsal hollow nerve chord. that develops into the brain and spinal chord.
Chordates human dorsal hollow nerve chord
Becomes a gelatinous disk found between vertebrae. Muscular, post anal tail.
Tunicates and amphioxus classification exeception
Are classified as chordates but are invertebrates
Cnidaria
Hydras, jellyfish, corals, sea anemones. Unique stinging cells called nematocytes.