Pattern Formation Flashcards
The development of specific ordered structures at specific locations.
Pattern formation
Outcome of morphogenesis:
- Specific body axes
- Anterior-Posterior
- Dorsal-Ventral
- Medial-Lateral
- Central-Left/Right - Unique organization (symmetry)
synthesized locally signaling molecules that diffuse and act over long distances to induce cellular responses and control growth and pattern throughout a tissue region
Morphogens
The morphogens:
- Cytoplasmic proteins (TFs)
- Signaling molecules
- Form concentration gradient
- Provide positional information
- Induce unique transcriptional responses
PATTERN FORMATION
At the organ level—multiple classes of differentiated cells must synchronize their duties to ensure that the organ as a whole is functional.
PATTERN FORMATION
At the organismal level : intricate coordination of all organ system is required to generate a functional, mature animal.
Life Cycle of Drosophila
Embryo
1 day - 1st instar larva
1 day - 2nd instar larva
1 day - 3rd instar larva
2 1/2 to 3 days - pupa
3 1/2 to 4 1/2 days - adult
Summary of Pattern Formation in Drosophila
Maternal genes > Gap genes > Pair-rule genes > Segment polarity genes > Homeotic genes
a class of segmentation genes in insects, primarily known for their role in establishing the periodic pattern of segments in developing embryos
Pair-rule genes
a class of genes in insects, like Drosophila, that establish the polarity (directionality) of each segment within a parasegment (a developmental unit) during embryonic development
Segment polarity genes
master regulatory genes that determine the identity of body segments and structures during the embryonic development of an organism
Homeotic genes
Anterior: Bicoid mRNA (through TFs Cortex, Grauzone, Staufen), becomes bicoid proteins that inhibits caudal mRNA and protein and permits hunchback mRNA and proteins.
Posterior: Nanos mRNA (through TF Oskar), becomes nanos protein that inhibits hunchback mRNA and protein and permits caudal mRNA and protein (Pumilio p55)
Gap genes
Define 4 broad regions in the egg:
Hunchback
Kruppel
Knirps
Giant
Define 7 stripes (Each stripe is a pair of segment)
are expressed as a result of differing concentrations of gap gene proteins.
Pair-rule genes
_____ identifies odd-numbered parasegments
eve (even-skipped)
____ identifies even-numbered parasegments
ftg (fushi tarazu)
will determine the boundaries and AP orientation of each segment
Define 14 stripes (Each stripe is a segment)
Segment polarity genes
Adult fly has ___ thoracic segments & ___ abdominal segments
3; 8
Responsible for unique differentiation of each segment by modifying cell fates; most are TFs, master regulator genes
Homeotic genes
Determine the AP axis and induce gap genes
Maternal effect genes
_________ define several broad areas and regulate _________, which refine the segment locations and regulate __________, which determine the boundaries and AP orientation of each segment.
Gap genes;
Pair rule genes;
Segment polarity genes
Together, the gap, pair rule, and segment polarity genes control expression of the ____, which define the identity of each segment.
Hox genes
