Chapter 13 Flashcards
What are homeotic mutants?
When one part of the body is transformed to resember another part.
What is a morphogen?
Molecule whose effects are concentration dependent and establish the pattern of tissue development and the body plan formation.
What are genetic toolkits?
The set of genes reposnible for the regulation of animal development, there are only a few dozen toolkit genes, mostly encode cell signaling proteins and transcription factors, and highly conserved across diverse species of animals.
What are the maternal-effect genes?
These are genes expressed in the mother and the gene product are depostited in the oocyte.
What are bicoid and nanos?
These are anterior and posterior genes that regulate expression and encode for transcription factors. These are mRNA that are tethered to the anterior and posterior ends of the unfertilized egg.
When are gene products present?
Before the expressio of the zygotic genome.
When can the maternal-effect genes impact the offspring?
Mutant phenotypes of maternal effect genes depend only on the genotype of the mother.
The toolkit genes are broken up into the following categories?
1.) Maternally expressed
2.) Zygotically expressed
What are gap genes?
Gap genes divide the embryo into broad regions. Segementation genes affect the number and organization of the body segments. Mutations in gap genes lead to large gaps in segmentation.
What are the pair rule genes?
The pair rule genes affect the development of pairs of segments. Pair rule genes act in more narrow region than do gap genes.
What are the segment polarity genes?
The segment polarity genes affected the organization of segments. Mutations in segment polarity genes lead to defects in segment polarity and number.
What do hox genes do?
They determine the identity of a structure or segment.
What is the relationship betwen the order of the Hox genes in the chromosome and the order of the body regions?
The order of the genes correspond tot he order of the body regions.
