L7 Flashcards
segmentation is found in which 3 phyla?
arthropods
annelids
vertebrates
segmentation is initiated in drosophila embryo as ____ parasegments
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what are the 3 classes of segmentation defects?
general a-p problems : maternal determinants
continuous segments affected : gap genes
alternate segments affected : pair rule genes
pair rule genes - what does this mean?
every other segment is gone
what do you call a mutant with two posteriors?
bicoid (bi-caudal)
mating homozygous mutant female to wild type male leads to _____ embryo, that is ____zygous
abnormal
heterozygous
embryo is a ____ when bicoid is produced
syncytium (no plasma membranes separate the nuclei)
_______ occurs after bicoid gradient is established
cellularization
where there is a lot of bicoid becomes the ____, where there is some bicoid becomes the ___, and where there is little bicoid becomes the ____
head
thorax
abdomen
the bicoid gradient provides ______ on distance from the anterior
positional information
bicoid is a _________ which regulates target genes by binding to their ________
transcription factor
promoters
what is an example of gene requiring high [] of bicoid? and a gene that requires low levels of bicoid
high: orthodenticle
low: hunchback
what are the two sources of hunchback?
maternal mRNA
zygotic transcription
is important for making anterior structures
Nanos is required only to repress ________ and nothing more - is NOT a transcription factor
hunchback mRNA translation
nanos keeps hunchback protein out of the ______ end of the embryo
posterior
_________ localization correlates with mutant phenotypes
mRNA
hunchback is an unusual gap gene, as it is expressed in a _______ rather than a block - and it has ____ and ______ sources
gradient
maternal
zygotic
the _____ is generated by hunchback acting as a morphogen
kruppel stripe
gap genes have _____ expression
zygotic
(except hunchback and caudal)
expression of gap genes marks the conversion of the initial gradients into ___________
broad stripes
what is even skipped pair rules?
expressed in odd numbered parasegments
lacks odd numbered parasegment
encodes transcriptional repressor
what is fushi tarazu pair rule?
expressed in even numbered parasegments
mutant lacks even numbered parasegments
encodes transcriptional activator
each pair rule stripe is regulated _______
independently
maternal mRNA inputs in the egg make broad protein __________. these then regulate expression of gap genes in ___________. the gap genes and maternal inputs regulate ______ thin stripes of pair-rule genes
concentration gradients
wide blocks
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