homeotic genes

mesoderm

partly fills the space between the ectoderm and the endoderm

What are the three layers

1) ectoderm 2) endoderm 3) mesoderm

Homeotic genes A) encode transcription factors that control the expression of genes responsible for specific anatomical structures. B) are found only in Drosophila and other arthropods. C) are the only genes that contain the homeobox domain. D) encode proteins that form anatomical structures in the fly. E) are responsible for patterning during plant development.

A

Homeotic genes contain a homeobox sequence that is highly conserved among very diverse species. The homeobox is the code for that domain of a protein that binds to DNA in a regulatory developmental process. Which of the following would you then expect? A) that homeotic genes are selectively expressed over developmental time B) that a homeobox-containing gene has to be a developmental regulator C) that homeoboxes cannot be expressed in nonhomeotic genes D) that all organisms must have homeotic genes E) that all organisms must have homeobox-containing genes

A

Two eukaryotic proteins have one domain in common but are otherwise very different. Which of the following processes is most likely to have contributed to this similarity? A) gene duplication B) RNA splicing C) exon shuffling D) histone modification E) random point mutations

C

Which of the following studies would not likely be characterized as eco-devo? A) the study of a particular species to see whether or not it has developmental regulation B) a study of the assortment of homeotic genes in the zebra C) a comparison of the functions of a particular homeotic gene among four species of reptiles D) studying the environmental pressures on developmental stages such as the tadpole E) a fossil comparison of organisms from the Devonian era

C

eventually these three layers develop into.....

all the tissues and organs of the adult animal

endoderm

lines embryonic digestive tract

Ectoderm

outer layer

What are Germ Layers?

the three layers produced by gastrulation (the progress where cell division slows takes up new locations that will allows it to form tissues and organs)