Developmental Genetics Flashcards
Gain-of-fxn mutations in Homeobox-Containing genes
Result is ANTERIOR to Posterior transformations
How many thoracic segments does a drosophila have?
- 3
- That’s why they have 6 legs
Fxn of Maternal Effect genes
Establish GRADIENTS from Ant. To Post. POLES of the egg
Gene Hierarchy in Drosophola
- Egg Polarity
- Segmentation genes
- Homeotic Genes
Fxn Segmentation Segment-Polarity Genes
Define 14 segments
Homeobox-Containing genes are activated in what direction?
3’ to 5’
- OPPOSITE of transcription
Sox Genes
- High mobility group domain that binds to MINOR groove on DNA Helix rather than the MAJOR groove
- Includes SRY gene
Overall time for Drosophila life cycle from Egg to Adult
9 days
How many Segmentation Genes are in Drosophila?
25
Drosophila dev gene Flow Chart
- Egg-Polarity
- Gap
- Pair-Rule
- Segment-Polarity
- Homeotic
Loss-of-fxn mutations in Homeobox-Containing genes
Results in POSTERIOR to Anterior transformations
Bithorax Complex
- Affects the dev. Of the POST. Thorax
- Affects the dev of the ABDOMINAL Segments
Antenna-Pedia Complex
- Affects the dev. Of the HEAD and THORAX
Egg polarity genes that establish Anterior-Posterior axis
- Bicoid
- Nanos
- Hunchback
“ Boobs N Hooters”
Homeobox
Highly conserved sequence of 180 NT
Pole cells
- Nuclei at one end of the blastoderm dev. Into Pole cells
- They become Primordial GERM Cells
Fxn of Homeotic Genes
Determine regional Characteristics
2 major groups of Homeotic genes in Drosophila
- Antenna-Pedia Complex
2. Bithorax Complex
Egg polarity genes that establish Dorsal-Ventral axis
- Dorsal
- Toll
- Cactus
“Dick to Cock”
Egg polarity genes in drosophila
MATERNAL Effect genes
- Important for establishment of the Dorsal-Ventral axes
- Important for establishment of the Anterior-Posterior axes
T-box genes
- Contain a Coserved T-box coding 180-200aa
- Plays a role in inducing MESODERMAL germ layer and in coordinating the outgrowth of the ARM or LEG
Homeotic Genes
Hox Genes
- Antenna-Pedia Complex
- Bithorax Complex
Forkhead (Fox) Genes
- Type of HLH family
- Expressed in many Developing Organs throughout the body
What are the Segmentation genes?
- Gap Genes
- Pair-Rule Genes
- Segment-Polarity Genes
Def. Of Homeobox-Containing Genes
- Highly CONSERVED Sequence of 180NT
- Codes for the 60aa HOMEO-DOMAIN found in homeodomain transcription factor
Fxn Segmentation Pair-Rule Genes
Define 7 Segments
Examples of Homeobox-Containing Genes
- Hox gene
- Pax gene
- POU genes
- Lim Protein Genes
What is a Morphogen?
- A protein that VARIES in [ ]
- Causes diff dev responses as a result of the [ ] differences
Zinc finger transcription factors
- These proteins have ZINC ions bound to polypeptide chain
- Cause to form FINGER-Like projections that can be inserted into the DNE helix
WT1
Aka Wilms Tumor
- Important for the development of the embryonic/adult kidney
What is larger: Homeobox or Homeodoman?
Homeobox
Helix-Loop-Helix Genes
- Code for basic HLH transcription factors
- Involved in HOMO-dimerization and HETERO-dimerization
- Important in Myogenesis
Characteristics of Homeobox-Containing Genes
- Major role in Vertebrates w/ regard to CRANIO-CAUDAL Segmentation
- Major role in development of organs
Fxn Segmentation GAP Genes
Defines BROAD regions in the egg
Major Homeobox-Containing Genes
- T-Box (Tbx) Genes
- Helix-loop-Helix Genes
- Forehead (Fox) Genes
