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Animal Diversity
N/A
35
Biology
Undergraduate 1
02/16/2014

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Term
How are animal tissues strengthened?
Definition
have extracellular matrix instead of cell wall
Term
What are animals?
Definition
multicellular, heterotrophic eukaryotes
Term
common features of animal development
Definition
blastula and gastrula
Term
Blastula
Definition
a hollow ball of cells in early development
Term
Gastrula
Definition
A blastula with an infolded layer of cells (early development)
Term
Hox genes
Definition
contain homeoboxes and are homeotic in function. function during development to specify features of an animal's body plan
Term
homeobox
Definition
180bp sequence of DNA that encodes a 60 amino acid homeodomain of a protein: three alpha-helices that can bind to a domain
Term
homeotic gene
Definition
a gene that determines the placement and identity of body parts
Term
transcription factors
Definition
regulators of the transcription of genes
Term
Parazoa
Definition
no tissues (sponges, placozoans)
Term
Eumetazoa
Definition
have tissues
can be radially or bilaterally symmetrical
Term
diploblastic
Definition
has 2 germ layers in embryo: ectoderm and endoderm
Term
triploblastic
Definition
3 germ layers in embryo: ectoderm, endoderm and mesoderm
Term
Mesoderm
Definition
found in triploblastic eumetazoans. important for muscle production
Term
Bilateral symmetry
Definition
associated with cephalization and motile animals
Term
what is the significance of bilateral symmetry to the lifestyle of an animal?
Definition
associated with cephalization (clustering of sensory apparatus, weapons and neurons in the anterior end). This suits an animal that is mobile and must deal with threats and opportunities that come from the direction in which it is moving
Term
What is the difference between a homeotic gene and a Hox gene?
Definition
A homeotic gene is a gene that controls the identity of body parts. A Hox gene is a gene that contains a homeobox (a certain DNA sequence) and that is homeotic in function. Hox genes are characteristic of animals; outside the animal kingdom, there exist genes with homeoboxes, but they are not homeotic in function, and homeotic genes, which do not contain homeoboxes.
Term
Would you expect an acoelomatous worm to have a blood vascular system?
Definition
No, you would not. In an acoelomate the mesoderm forms a solid mass of cells, and there is no room for the differentiation of separate organs or other structures, such as a blood vascular system, within this mass.
Term
Suppose you dug up a fossil which your geologist friend estimates to be 700 million years old. What features would you look for to classify it as an animal and not an alga?
Definition
You would expect the organism to be multicellular and to lack cell walls. Traces of cell walls persist in fossilized organisms much better than does the matrix that holds animal cells together in tissues, so it might be possible to determine the presence or absence of walls in your fossil. Also, if your fossil had a worm-like morphology, as many groups of animals do, that would strongly suggest that it was an animal and not an alga
Term
Why, evolutionarily speaking, do animals have intercellular junctions unlike those of other organisms, such as algae, plants, and fungi?
Definition
A reasonable hypothesis is that the common ancestor of animals, plants and fungi was unicellular, as was the later common ancestor of animals and fungi. Multicellularity evolved independently in each group after divergence occurred. It would not be surprising, therefore, if the structures that evolved in each lineage to serve the functions of support and communication between cells were different
Term
Why are the Doushantuo fossils suspected to be animal embryos?
Definition
They are composed of cells that become smaller the more numerous they get. This is an attribute of early animal embryos today
Term
cephalization
Definition
the anterior concentration of neural processing power, sensory apparatus, and sometimes weapons
Term
Protostome
Definition
One mouth (early development)
Term
Deuterostome
Definition
two mouths (early development)
Term
determinate cleavage
Definition
early cleavage products lose the ability to form complete embryos by themselves
when the cell begins to divide, the daughter cell is limited. If parts are missing, it will not develop fully
Term
indeterminate cleavage
Definition
early cleavage products can form complete embryos by themselves
Term
Coelomate
Definition
coelom is lined with mesoderm only
Term
Pseudocoelomate
Definition
lined with endoderm and mesoderm
Term
acoelomate
Definition
no coelom; mesoderm forms a solid mass of cells
Term
coelom
Definition
provides space for the development of organs
cushions organs and allows independent movement of organs
allows for development of a blood vascular system
can serve as hydrostatic skeleton
separates gut muscles and body wall muscles
coelomates can be larger and more active than acoelomates
Term
what is the closest relative to animals still alive today?
Definition
Choanoflagellates. They have cells similar to choanocytes (collar cells) found in sponges
Term
Doushantuo fossils
Definition
600-570 million years ago.
found in China about twenty years ago
look like animal embryos
cells become smaller as they become more numerous
Term
830-635 million years ago
Definition
early animal evolution might have been stimulated by the end of the Snowball Earth phase
Term
the Ediacarans
Definition
585-542 million years ago
the first multicellular organisms
looked like sponges, cnidarians (radially symmetric), molluscs, echinoderms, worm tracts
Term
by what time were half of the animal phyla on Earth today represented?
Definition
the Cambrian explosion (542-525 million years ago)
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