Heterotrophs: Derive organic nutrition externally; Common ancestor are protists; Microbrial eukaryotes
Animals: Eukaryotic; Multicellular; Heterotrophs; Internal processes to break down food.; Most can move (except for sponges).
Heterotrophs: Filter feeders; Sponges; Herbivores; Goats; Predators; Owls; Parasites; Lampreys; Detritivores; Shrimp; Omnivores; Humans; Carnivores; Bats
Cell Surface of an Animal: No cell wall usually; Made of glycoprotein, carbs, proteins, cytoskeleton
Extracellular Matrix ECM: Exists just outside the cell membrane; Contains collagen; Triple-alpha helix; Contains proteoglycans; Proteins + Carbs
Tight Junctions: In animal cells; Epithelial cells; Proteins connect neighboring cells tightly; Prevents leaky gut; Barrs movement of dissolved materials between cells.
Desmosomes: In animal cells; Link adjacent cells tightly, but permit materials to pass in the intercellular space.
Gap Junctions: In animal cells; Let adjacent cells communicate; Allows for sharing ions, signals.; Have connexins (channel proteins) that span into adjacent cell membranes (hydrophilic channel) for sharing nutrients/signals.

Tissue Layers

Germ Layers

Gastrulation determines phylogeny of organism.

Blastopore: 1st opening during gastrulation.
Gastrulation: Animal egg to 1st ball of cells.; Differentiation of cell layers into ectotherm (outer), mesoderm (middle), endotherm (inner).
Protosomes: Insects; Gastrulation: 1st blastopore develops into the mouth.
Deuterosomes: Humans; Gastrulation: 1st blastopore develops into the anus.

Acoelomate Anti-Coelomate: Body cavity not fluid.; No internal organs, only gut.; Not a true body cavity, no distinct structure.; Flat worms
Psuedocoelomate Semi-Coelomate: No mesoderm.; Has unorganized internal organs.; Fluid-filled body cavity.
Coelomate True body cavity: Internal organs are organized w/ the mesoderms.; Body cavity lined with mesoderms.

Gastrovascular Cavity: Cnidaria; Sponges, jellies, anenomes
Open Circulatory System: Have hemolyph similar to blood; Anthropods; Snails, clams, insects
Closed Circulatory System w/o an endothelium: Annelids (segmented worms); Squid, octopus; No red blood cells.
Closed Circulatory System lined with endothelium: Humans, mammals, amphibians, reptiles, birds

HOX Genes Homeotic Genes: HOX genes code for HOX proteins.; HOX = developmental/segment genes.; PDM
HOX Proteins: Transcription factors that bind dna to regulate the activity of many target genes at once.; Turn mRNA synthesis on or off to alter protein synthesis.; Matches with sequence in multiple parts of a gene to start (more common) or stop transcription for multiple genes at once.

HOX genes are related by common ancestry
UBX7 gene determines how many segments in insect thorax.
HOX gene expression determines body morphology around a homologous species.
HOX genes are conserved through evolution.
In mammals, HOX genes are similar, but not identical.
HOX genes act to position body parts.
Changes in HOX genes correlate w/ evolutionary changes in morphology.
Changes in # of HOX genes = changes in symmetry axis & body pattern.
- More genes = more complex.
Range (where) HOX genes are expressed = changes in body segments in insects.
Different HOX alleles = form changes (legs or no legs).
They change and regulate function in downstream genes.
- = Changes in form/function.

Complete: Changes are dramatic.; HOX genes change from juvenille to metamorphosizing larvel tissues.
Incomplete: Changes are gradual, less dramatic.; HOX genes remain active throughout metamorphosis.