Intro to Animal Diversity Flashcards
Animal cell extracellular matrix
collagen, other glycoproteins, proteoglycans
intercellular junctions only in animals
gap junctions, desmosomes, tight junctions
Animal tissue
nervous, muscle. both can conduct electrical signals
Common features of early development of animals
blastula-hollow ball of cells
gastrula-blastula with infolded layer of cells
Hox genes
animals have. contain homeoboxes and homeotic in function. function during development to specify features of animal’s body plan. products determine developmental fate of groups of cells
homeobox
180bp sequence of DNA, encodes for homeodomain of protein: 3 alpha-helices that can bind to DNA, can bind to major groove of DNA
homeodomain
60amino acid
homeotic gene
gene determining placement and identity of body parts
transcription factors
regulators of transcription of genes
Variation in Hox gene activity
leads to variation in animal body plan. evolutionary significance to understand diversification of phylum and class. Evolutionary development
Parazoa
no tissue, some weak cell specialization. eg. sponges, placozoans
Eumetazoa
tissues
Radial symmetry
oral-aboral, often sessile or planktonic (drifting). threats/opportunities from all directions
Diploblastic
2 germ layers (ectoderm and endoderm)
Bilateral symmetry
have 3 germ layers, applies to most animals. Clade Bilateria. anterior-posterior. dorsal-ventral. right-left. cephalization. suited for active forms, encounter world from one direction
Triploblastic
3 germ layers: ectoderm, mesoderm, endoderm. All protostomes and deuterostomes are triploblastic
Determinate cleavage
early cleavage products lose ability to form completely embryos by themselves
Indeterminate cleavage
early cleavage products can form completely embryos by themselves
Protostome development
spiral and determinate 8-cell stage, solid masses of mesoderm split and form coelom, mouth develops from blastopore
Deuterstome development
radial and indeterminate eightcell stage, folds of archenteron form coelom, anus develops from blastopore
coelomate
coelom is lined with mesoderm (muscle) only. can be large and more active than acoelomates
pseudocoelomate
pseudocoelom is lined with endoderm and mesoderm
acoelomate
no coelom, mesoderm forms a solid mass of cells
functions of coleom
space for organ development
cushions organs and allows movement of organs
allows development of a blood vascular system
can serve as a hydrostatic skeleton
separates gut muscles and body wall muscles.
last common ancestor of animals
colonial protist, 800-675 mya
animal near-relations alive today
choanoflagellates, collar cells. signalling, adhesion molecules
stimulation of early animal evolution
end of Snowball EArth phase, 830-635 mya
Doushantuo fossils
approx 600-570 mya, look like animal embryos. cells became small as they became more numerous
Ediacarans
585-542 mya, first large multicellular organisms. looked like sponges, cnidarians, molluscs, echnioderms, worm tracks, nothing else
Cambrian explosion
542-525 mya, half of animal phyla on EArth today were represented. many basic body plans appeared and many diversified. basic body plan=phylum
Burgess shale
key fossil formation, 505 mya, soft parts of organisms preserved
Why did Cambrian explosion happen?
new predator-prey relationships, new weapons, new defences, new modes of locomotion, new senses-eyes. rise in atmospheric O2-support more active metabolism. evolution of Hox genes-great variability=greater morphological variation
