5.7.6: Key Terms
- Page ID
- 97163
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)- acoelomate
- animal without a body cavity
- bilateral symmetry
- type of symmetry in which there is only one plane of symmetry, so the left and right halves of an animal are mirror images
- blastopore
- opening into the archenteron that forms during gastrulation
- blastula
- 16–32 cell stage of development of an animal embryo
- body plan
- morphology or defining shape of an organism
- Cambrian explosion
- time during the Cambrian period (542–488 million years ago) when most of the animal phyla in existence today evolved
- cleavage
- cell divisions subdividing a fertilized egg (zygote) to form a multicellular embryo
- coelom
- lined body cavity
- Cryogenian period
- geologic period (850–630 million years ago) characterized by a very cold global climate
- determinate cleavage
- cleavage pattern in which developmental fate of each blastomere is tightly defined
- deuterostome
- blastopore develops into the anus, with the second opening developing into the mouth
- diploblast
- animal that develops from two germ layers
- Ecdysozoa
- clade of protostomes that exhibit exoskeletal molting (ecdysis)
- Ediacaran period
- geological period (630–542 million years ago) when the oldest definite multicellular organisms with tissues evolved
- enterocoely
- mesoderm of deuterostomes develops as pouches that are pinched off from endodermal tissue, cavity contained within the pouches becomes coelom
- eucoelomate
- animal with a body cavity completely lined with mesodermal tissue
- Eumetazoa
- group of animals with true differentiated tissues
- gastrula
- stage of animal development characterized by the formation of the digestive cavity
- germ layer
- collection of cells formed during embryogenesis that will give rise to future body tissues, more pronounced in vertebrate embryogenesis
- Hox gene
- (also, homeobox gene) master control gene that can turn on or off large numbers of other genes during embryogenesis
- indeterminate cleavage
- cleavage pattern in which individual blastomeres have the character of "stem cells," and are not yet predetermined to develop into specific cell types
- Lophotrochozoa
- clade of protostomes that exhibit a trochophore larvae stage or a lophophore feeding structure
- mass extinction
- event or environmental condition that wipes out the majority of species within a relatively short geological time period
- Metazoa
- group containing all animals
- organogenesis
- formation of organs in animal embryogenesis
- Parazoa
- group of animals without true differentiated tissues
- protostome
- blastopore develops into the mouth of protostomes, with the second opening developing into the anus
- pseudocoelomate
- animal with a body cavity located between the mesoderm and endoderm
- radial cleavage
- cleavage axes are parallel or perpendicular to the polar axis, resulting in the alignment of cells between the two poles
- radial symmetry
- type of symmetry with multiple planes of symmetry, with body parts (rays) arranged around a central disk
- schizocoely
- during development of protostomes, a solid mass of mesoderm splits apart and forms the hollow opening of the coelom
- spiral cleavage
- cells of one pole of the embryo are rotated or misaligned with respect to the cells of the opposite pole
- triploblast
- animal that develops from three germ layers