ch 21a Flashcards
where do tissues develop from in animals?
embryonic layers
do eukaryotic cells in animals have cell walls?
no
animals have blastula which is:
hollow ball stage of development
where do cells bind to in animals?
extracellular matrix
most animals and only animals have Hox genes which:
regulate the development of body form
Most animals are invertebrates or vertebrates
invertebrates
Vertebrates include
mammals, amphibians, reptiles and fish
When animals reproduce sexually, what is the dominant stage?
Diploid
Cleavage
after the sperm fertilizes an egg, the zygote undergoes rapid cell division
What does cleavage lead to?
formation of a multicellular, hollow blastula
Gastrulation
a process blastula undergoes that forms a gastrula with different layers of embryonic tissues
Radial symmetry
no front and back or left and right
Bilateral symmetry
two sided symmetry
4 Things bilateral symmetry has
- dorsal (top side), ventral (bottom side)
- a right and left side
- anterior (head), posterior (tail)
- cephalization: development of head
Tissues
collections of specialized cells isolated from other tissues by membranous layers
3 germ layers
ectoderm, endoderm, mesoderm
Ectoderm
the germ layer covering the embryo’s surface
Endoderm
the innermost germ layer and lines the developing digestive tube, called the archenteron
Mesoderm
middle layer develops into notochord, the lining of the coelom,
muscles, skeleton, gonads, kidneys, & most of the circulatory system
Who possesses body cavities?
most triploblastic organisms (all 3 germ layers)
Coelom
true body cavity derived from a mesoderm
Coelomates
animals that possess a true coelom
pseudocoelom
a body cavity derived from a mesoderm and endoderm
pseudocoelomates
triploblastic animals that posses a pseudocoelom
