Animal Development Flashcards
(24 cards)
What are the key events of fertilization?
Sperm-egg recognition → Sperm entry → Egg activation → Nuclei fusion
What structures surround the egg in echinoderms?
Vitelline envelope and jelly coat
What structures surround the egg in mammals?
Zona pellucida and granulosa cells
How is polyspermy prevented?
Fast Block: Membrane depolarization
Slow Block: Cortical reaction → Formation of fertilization envelope
What occurs during cleavage in early development?
Rapid cell divisions without growth, forming a morula, then a blastula
What is holoblastic cleavage and where is it found?
Complete cleavage
Radial (deuterostomes): e.g., sea stars
Spiral (protostomes): e.g., mollusks
What is meroblastic cleavage and where is it found?
Partial cleavage in telolecithal eggs, e.g., birds and reptiles
What are the three germ layers formed during gastrulation?
Ectoderm: Skin and nervous system
Mesoderm: Muscles, bones, circulatory system
Endoderm: Digestive and respiratory systems
How does gastrulation occur in echinoderms?
Through invagination
How does gastrulation occur in birds and mammals?
Through the primitive streak
How does the nervous system form?
Neural plate → Neural groove → Neural tube
What is the function of the chorion?
Gas exchange
How does the circulatory system begin to form?
From the development of heart and blood vessels
What is the function of the amnion?
Fluid protection for the embryo
What is the role of the allantois?
Waste storage in birds/reptiles; umbilical vessels in mammals
What is the function of the yolk sac?
Nutrient supply to the embryo
What is the order of gene regulation in development?
Maternal effect genes → Segmentation genes → Homeotic genes (Hox genes)
What does differential gene expression mean?
Cells have the same DNA but perform different functions due to gene expression differences
What are totipotent stem cells?
Cells that can become any cell type, including extraembryonic tissues
What are pluripotent stem cells?
Cells that can become many, but not all, cell types
Why is Drosophila melanogaster used in developmental biology?
To study Hox genes and segmentation
Why is C. elegans used in developmental studies?
For cell lineage tracking
Why is Danio rerio (zebrafish) a useful model organism?
To study vertebrate development
What makes Mus musculus (mouse) valuable in developmental biology?
It’s a key model for studying mammalian genetics
