Compare forward & reverse genetics.
Forward: phenotype to genotype
Reverse: the reverse
Describe a relevant feature of each model organism.
S. cerevisiae: can exist as haploid or diploid.
C. elegans: can trace the fate of each cell.
D. melanogaster: shares 75% of human disease-causing genes.
D. rerio (zebrafish): easily treated w/ small molecules for drug & toxicity screens.
M. musculus (mice): commonly used for preclinical testing.
Axolotls: can regenerate limbs.
Planaria: can regenerate everything.
Describe the pulse-chase experiment.
Incubate slices of pancreatic tissue w/ radioactive leucine (pulse), then with non-radioactive solution (chase).
Then visualize organelle composition.
Describe temperature sensitive mutations.
Produces a functional protein at permissive temperatures but a less/non-functional protein at restrictive temperatures.
Often caused by single a.a substitution within a protein’s hydrophobic core.
Sec gene products can produce a protein-coated vesicle in vitro given which three (or seven) components?
Purified gene products (Sar1, Sec23, Sec24, Sec13, Sec31 genes), purified ER, & GTP.
COP-II vesicles can form after.
Describe gastrulation.
Inner cell mass further differentiates into the epiblast, which then forms an epitheilal layer.
Few days post-implantation, migration through the primitive streak occurs, forming ectoderm, mesoderm & endoderm.
Gastrulation establishes the three main body axes: anterior/posterior (top/bottom), ventral/dorsal (front/back), left/right.
Describe anterior-posterior patterning.
Genetically controlled. In Drosophila:
- Hox genes (TFs along a single chromosome) are positioned in order of expression; positional identity.
Also, Planar Cell Polarity.
Describe the role of morphogens.
Diffusible signals that exert graded effects. Allows activation of pathways at certain levels, or a combination of different pathways.
The gradient causes downstream production of various TFs.
Contributes to combinatorial signaling & cellular memory.
*Ventral: Shh, Dorsal: BMP
Describe the role of Lats1/2 & YAP
Cell division is regulated by Lats1/2 pathway (among others); Yap turns on different genes in later stages of development, causing cell proliferations by acting on certain genes.
Lats1/2 inhibits Yap by phosphorylation.
