L7

Question 1

segmentation is found in which 3 phyla?

Answer 1

arthropods
annelids
vertebrates

Question 2

segmentation is initiated in drosophila embryo as ____ parasegments

Answer 2

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Question 3

what are the 3 classes of segmentation defects?

Answer 3

general a-p problems : maternal determinants

continuous segments affected : gap genes

alternate segments affected : pair rule genes

Question 4

pair rule genes - what does this mean?

Answer 4

every other segment is gone

Question 5

what do you call a mutant with two posteriors?

Answer 5

bicoid (bi-caudal)

Question 6

mating homozygous mutant female to wild type male leads to _____ embryo, that is ____zygous

Answer 6

abnormal

heterozygous

Question 7

embryo is a ____ when bicoid is produced

Answer 7

syncytium (no plasma membranes separate the nuclei)

Question 8

_______ occurs after bicoid gradient is established

Answer 8

cellularization

Question 9

where there is a lot of bicoid becomes the ____, where there is some bicoid becomes the ___, and where there is little bicoid becomes the ____

Answer 9

head
thorax
abdomen

Question 10

the bicoid gradient provides ______ on distance from the anterior

Answer 10

positional information

Question 11

bicoid is a _________ which regulates target genes by binding to their ________

Answer 11

transcription factor
promoters

Question 12

what is an example of gene requiring high [] of bicoid? and a gene that requires low levels of bicoid

Answer 12

high: orthodenticle
low: hunchback

Question 13

what are the two sources of hunchback?

Answer 13

maternal mRNA
zygotic transcription
is important for making anterior structures

Question 14

Nanos is required only to repress ________ and nothing more - is NOT a transcription factor

Answer 14

hunchback mRNA translation

Question 15

nanos keeps hunchback protein out of the ______ end of the embryo

Answer 15

posterior

Question 16

_________ localization correlates with mutant phenotypes

Answer 16

mRNA

Question 17

hunchback is an unusual gap gene, as it is expressed in a _______ rather than a block - and it has ____ and ______ sources

Answer 17

gradient

maternal
zygotic

Question 18

the _____ is generated by hunchback acting as a morphogen

Answer 18

kruppel stripe

Question 19

gap genes have _____ expression

Answer 19

zygotic

(except hunchback and caudal)

Question 20

expression of gap genes marks the conversion of the initial gradients into ___________

Answer 20

broad stripes

Question 21

what is even skipped pair rules?

Answer 21

expressed in odd numbered parasegments
lacks odd numbered parasegment
encodes transcriptional repressor

Question 22

what is fushi tarazu pair rule?

Answer 22

expressed in even numbered parasegments
mutant lacks even numbered parasegments
encodes transcriptional activator

Question 23

each pair rule stripe is regulated _______

Answer 23

independently

Question 24

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

Answer 24

concentration gradients

wide blocks

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