Development 1 Flashcards
What is Development?
Changes that occur throughout the life cycle
What is Fertilization?
Process of sperm infiltrating Ovum / Egg. Results in Diploid, Totipotent Zygote.
What does it mean when a zygote is referred to as Totipotent?
Zygotes have the potential to give rise to multiple types of cells.
What are 3 Effects of Fertilization?
- Restore Diploid Condition
- Determine Sex of Offspring
- Activate Egg/Ovum - trigger reactions that promote development
SEQ Fertilization - Describe Acrosomal Reactions
1.) Sperm pushes through follicle cells of the Ovum, bind to receptors in the Zona Pellucida
2.) Once they bind, Acrosome bursts & releases enzymes that help the sperm navigate through the Zona Pellucida
3.) Plasmogamy Occurs
SEQ Fertilization - Describe the Cortical Reaction
1.) Once Plasmogamy occurs, Calcium ions produced in the Smooth ER are secreted into the Egg
2.) Calcium ions trigger release of Cortical Granules - fuse with Plasma Membrane
3.) Enzymes are released, trigger Slow Block.
SEQ Fertilization. What occurs during slow Block in Mammals.
1.) Zona Pellucida Hardens
2.) Receptors on Zona Pellucida are altered, Sperm cannot bind to receptors anymore - preventing polyspermy.
What occurs during cleavage
Fast mitotic divisions without cell growth
____ affects the pattern of Divisions.
Yolk
What is Yolk?
Food source of developing embryo
SEQ Cleavage. List the process of cleavage in order.
_A.___ develops into Embryo.
Embryo undergoes __B.__, forms Blastula. (Hollow embryo with blastoceal)
A.) Zygote
What are the 3 Patterns of Cleavge?
1.) Equal Holoblastic
2.) Unequal Holoblastic
3.) Meroblastic
CC Equal Holoblastic and Unequal Holoblastic.
- Equal Holoblastic has cells of the same size
- Unequal Holoblastic has cells of different sizes due to Yolk Distribution
What occurs in Meroblastic cleavage?
Only Regions without Yolk divide completely
