L2 - Taxonomy and Asymmetrical animals Flashcards
(51 cards)
What are the two divisions to the Linnaean system?
Binomial and hierarchical
What is the theory of evolution?
Species are not immutable - they change or adapt. The agent that produces these changes is natural selection.
What is the definition of phylogeny?
Evolutionary history
What is the definition of systematics?
Study of biology in evolutionary context
What is the definition of cladistics?
An examination of the order in which organisms evolved - it draws phylogenetic trees called cladograms
What is Taxon 1?
Monophylogeny
What is Taxon 2?
Paraphylogeny
How can we study evolution and produce these cladograms?
By examining the structure (morphology) of fossils
What are newer techniques for studying evolution?
Evolution is all about genetic change, e.g. mutations - sequence differences in nucleic acids leading to changes in protein seq. Nucleic acid sequencing - usually 18S rRNA. Developmental biology e.g. Hox genes that regulate development, this is known as molecular evolution.
Do new techniques for studying evolution tell us the time of divergence?
Perhaps - if evolution occurs at a linear rate
What is an example of a molecular clock?
Evolution of cytochrome c. In this case the molecular clock keeps good time.
How did animals first evolve?
Most likely evolved from choanoflagellates. Consist of choanocytes, unlike multicellular animals, all cell function similarly and separately.
What are the theories of animal evolution?
Colonial protist, an aggregate of identical cells. Hollow sphere of unspecialised cells, beginning of cells specialisation, infolding, digestive cavity, grastrula-like ‘protoanimal’
How do true animals differ from choanoflagellates?
Multicellularity - integration of cells (communication) and differentiation. Germ cells - spermatozoa and eggs - haploid. Collagen - a glycoprotein to hold cells together
What are some examples of Parazoa?
Porifera - sponges, Placozoa - ‘flat animals’
Stage 1 of True animals from choanoflagellates?
Parazoa - animals with no tissue differentiation - gave rise to modern day sponges. Eumatazoa - all other animals with true tissues
Stage 2 (Radiata) of True animals from choanoflagellates?
Radiata - Animals with radial symmetry and diploblastic larvae. Diploblastic - ectoderm (outer layer) and endoderm (gut etc)
What are some examples of Radiata?
Cnidaria - hydra, jellyfish, sea anenomes, corals. Ctenophora - comb jellies.
Stage 2 (Bilateria) of True animals from choanoflagellates?
Bilateria - animals with bilaterial symmetry and triploblastic. Triploblastic - ectoderm (outer layer), mesoderm (connective), endoderm (glandular).
What are the steps in development in bilaterial animals and formation of 3 layers?
Zygote, Cleavage, B-cell stage, Cleavage, Blastula (hollow ball), gastrulation, gastrula (blastopore, ectoderm, endoderm, mesoderm, archenteron)
What makes up the Ectoderm (outer layer)?
Cells of the epidermis, neuron of brain, neuron of peripheral nervous system.
What makes up the Mesoderm (middle layer)?
Cells of the notochord, skeletal muscle cells, kidney tubule cells, red blood cells
What makes up the Endoderm (inner layer)?
Pancreatic acinar cells, thyroid follicular cells, lung alveolar cells
What do the triploblastic layers need to be considered in?
Their complexity in the bauplan.