Final Flashcards
Morphogen
Molecule that elicits different responses depending upon its concentration
Canoncial wnt pathway
Double negative gate
HOX genes
Genes regulated by the protein products of gap, pair-rule, and segment polarity genes, specifically the characteristic structures of each segment
Mutations can result in the transformation of one segment into another
Important for the placement of limb buds, early kidney, limb bud patterning, imaginal disks
Gastrulation
Movement and rearrangement of blastomeres to form the three germ layers that will comprise the embryo - ectoderm, endoderm, mesoderm
Cre-lox
- Cre is an enzyme that recognizes loxp DNA sequences
- The mouse is genetically engineered to express cre under a specific cell-type promotor
- A reporter gene is placed downstream of a loxP stop
- Cre removes stop cassete allowing the reporter to be expressed
Allows for a KO of a gene in specific tissues
CRISPR KO
- guide RNA directs the Cas9 enzyme to genome location
- Cas9 makes a double strand break in the DNA at the location
- The gene is often repaired incorrectly
CRISPR Knock In
- guide RNA directs the Cas9 enzyme to genome location
- Cas9 makes a double strand break in the DNA at the location
- Donor DNA with homology arms identical to the target sequence is also introduced
- The cell repairs the damage with the donor DNA template
Lineage Tracing
Using Cre-lox for brainbow in mice
Molecular Motors
Proteins that convert chemical energy into mechanical work.
Dynein (Bcd) and kinesin (nos) transport the mRNAs in the unfertilized drosophila egg
Find it
The correlation of a molecule or structure w/ a function, the molecule has to be present at the right time and place
- Establishes connection
- Fluorescent tracing
- In situ hybridization ( detect the presence and location of specific mRNA at the right time and tissue)
Loose it
The loss of function - get rid of the molecule or structure by mutation or inhibitors
- When you lose the molecule do you lose its function?
- Establishes necessity
- CRISPR KO
- Laser Inhibition
- RNAi
Move it
If you put the moleculor structure in a new place, do you get the function appearing
- Establishes sufficiency
- Transplantation experiment
- To new location or different organism.
Cell potency
A cell’s ability to differentiate into different types of cells
Stem Cells
Make more than one cell type, typically a closely related family
Progenitor Cells
Can differentiate into multiple cell types, but can only renew a limited number of times
Bicoid / Nanos
In the unfertilized drosophila egg, there is anchored bicoid in the anterior and anchored Nos in the posterior that’s deposited by the maternal genes before fertilization.
Upon fertilization, the localized bcd and nos mRNA are translated into protein gradients.
Bcd protein acts as a txn factor and hunchback is also a txn factor that is activated by bcd
Nos protein represses translation of maternal Hb mRNA in the anterior through 3’ UTR
Bcd protein inhibits Cad mRNA through 3’ UTR
How to Maintain Gene Expression
Feedback loops
- autocatalytic feedback loop uses wnt and hh to keep segment polarity genes on
Maternal Effect Lethal Mutation
A gene whose product is made by the mother, but is required in the embryo for the early development to proceed normally.
- mom makes and pre-packages the RNA into the egg
- Zygote’s phenotype depends on the mother’s genotype
Capacitation
A set of physiological changes by which mammalian sperm become capable of fertilizing an egg
- ability to perform acrosome reaction
- ability to bind to an egg
Chemotaxis
Cell orientated movement in response to a chemical gradient
- Sperm Activating Peptides (SAPs) in sea urchin
- Progesterone in mammals
Competence
A cell’s ability to respond to specific signaling cues and undergo a particular developmental fate.
Polyspermy in sea urchins
Multiple sperm trying to fertilize
Fast block is electrical and transient, Bindin proteins on sperm match to egg receptors and an influx of sodium ions block polyspermy
Slow block is permanent and slow - cortical granule reaction
- IP3 opens Ca channel
- CA causes exocytosis of cortical granules
- Fertilization envelope forms
Acrosome reaction
Egg polysaccharides in jelly bind to sperm receptors. Ca++ channels open, Na+ influx/ H+ epplux, Phospholipase enzyme releases secondary messenger. Acrosome is released from sperm head to help sperm penetrate the egg jelly layer and zona pellucida
Neural Crest Cells
- unique to vertebrates
- Arise from dorsal neural tube and migrate
- Transient
- Give rise to multipotent progenitors
Polyspermy in Mammals
Slow block that releases Juno
-
Slow block that disable ZP2
- the cortical granules release enzymes that digest the proteins ZP2 and ZP3, preventing them from binding to sperm
Zinc Spar
- A rush of zinc is released into zona pellucida after binding, this acts as a chemoreppelent to counteract progesterone
