lecture 26, 27, 28 Flashcards
organizers
cells that have the ability to organize the development of surrounding
tissues
morphogens
molecules produced by the organizer that
induce various responses in surrounding tissue in a
concentration-dependent manner
housekeeping genes
genes that encode for proteins that function in essential processes in all cells of the body
development toolkit genes
encodes for proteins that function in development to implement basic developmental decision and are widely conserved
zygotic gene
a gene that its knockout produces a phenotype regardless if it is absent from the oocyte or the sperm
maternal-effect gene
a gene that its knockout produces a phenotype when absent in the oocyte but not the sperm
how do you determine what gene links to what developmental role?
identify the gene that is not expressed and match that to the organ that is not developed properly
what does immunolocation do?
determines where a protein is located in a cell or tissue
what does in situ hybridization do?
identifies where a gene is expressed by locating its mRNA
how does immunolocation detect proteins?
it utilizes an antibody that is specific to the target protein
how does in situ hybridization detect mRNA?
It utilizes complementary RNA probe to pair with the target mRNA
what type of gene is a bicoid?
maternal-effect gene
what is the consequence of a bicoid mutant?
the larvae develop without a head region
gap genes
affects the formation of a large embryonic regions
pair-rule genes
act at alternating segmental boundaries
segment-polarity genes
affect patterning within each segment
what is the order in which segmentation genes are expressed or developed?
bicoid -> gap -> pair-rule -> segment-polarity
are bicoid proteins maternal or zygotic?
maternal
are gap genes maternal or zygotic?
zygotic
are pair-rule genes maternal or zygotic?
zygotic
are segment-polarity genes maternal or zygotic?
zygotic
list the two types of gap genes as part of lecture
kruppel and knirps
list the four types of pair-rule genes as part of lecture
even and odd skipped, paired, runt
list the two types of segment-polarity genes as part of lecture
gooseberry and patched
homeotic genes
genes that regulate the development of anatomical structures and their functions are conserved
what is the most common result of a mutated homeotic gene?
misplacement of anatomical structures
homeotic transformations
when a normal body part is replaced by another due to a mutation
forward genetic screen
apply random mutagen to a wild-type organism, identify a phenotype of interest and clone the gene that when mutated is causing the phenotype
reverse genetic screen
identifying the gene sequence and using the information to directly mutate the gene and only then identify the phenotype
what does the Ubx gene do?
promotes hind-wing development and repress forewing development
what does a loss-of-function mutation in Ubx result in?
the hind wing transforms into a forewing; can fly but is unable to stabilize properly
what does a gain-of-function mutation in Ubx result in?
the forewing transforms into a hindwing; can no longer fly
what does the Antp gene do?
controls the development of legs/other body parts in the thoracic segment
what does a gain-of-function mutation in Antp result in?
legs develop where antennas should be
homeodomain
domain of 60 amino acids found within a large number of transcription factors
what can homeodomains do?
form helix-turn-helix structures and bind DNA in a sequence-specific manner
what type of gene is Dorsal?
maternal-effect gene
what does Dorsal encode for?
a transcription factor that is expressed in a gradient along the DV axis
synergistic effect
effect is greater than additive
enhanceosome
a large protein complex and the enhancer they bind that acts synergistically to activate transcription
how far do enhanceosomes typically act from?
further than 50 Kb
what is needed for the proteins in each enhansosome to act synergistically?
the distance between proteins in the enhanceosomes needs to be maintained
what can enhancers be an example of?
cis-regulatory elements
what does the Hunchback protein require to activate its transcription?
Bicoid binding
what increases the heaviness of a hunchback expression being expressed?
an increase in bicoid elements
what happens when there are increased sites a gap gene can have?
It can be activated with a lower concentration of bicoid proteins
what is meant by the cis-acting regulatory elements of individual genes are controlled independently?
none of the elements rely on one another for expression
With regard to the strip two enhancer, what proteins repress its concentation/expression?
kruppel and giant proteins
What proteins act as activators of the eve stripe two element?
bicoid and hunchback proteins
how can development be regulated?
by the binding of proteins to mRNA
where does developmental regulation take place?
the 3’UTR
What happens when GLD-1 binds to the 3’UTR of glp-1’s spatial control region?
it prevents glp-1 translation in the cells that express GLD-1; is the foundation of transitioning from proliferation to differentiation
what other kind of mRNA can regulate development?
microRNA
what does let-7 do?
it down-regulates cell division in hypodermal cells after transition to the adult stage
what does let-7 need to be able to down-regulate cell division?
it binds to lin-41’s 3’UTR
what is lin-41?
a translational repressor
what occurs if lin-41 is active?
cells continue to divide
what occurs if lin-41 is inactive?
cells stop dividing and begin to differentiate
what is polydactyly?
a genetic condition where one is born with additional fingers or toes than the considered normal amount
AP axis
head to tail and/or front to back
DV axis
back to belly and/or top to bottom
