exam 2- axis formation & embryo development

Question 1

developmental progression depends on two processes:

Answer 1

1- polarity formation: A-P and D-V axis polarity formed from gradients

2- formation of body segments: parasegments and embryonic segments give rise to adult segments

Question 2

Kruppel, a gap gene, reads two values in response to the dose of ___ protein

Answer 2

hunchback

Question 3

a concentration above minimal threshold of Hb ___ the expression of Kr

a conc above the max threshold of Hb __ the expression of Kr

Answer 3

activates
inactivates

Question 4

3 major classes of genes controlling development and differentitation

Answer 4

1- maternal effect genes
2- segmentation genes
3- homeotic genes

Question 5

maternal effect genes set up/establish what?

Answer 5

set up the A/P and D/V axes, framework of positional info (spatial distributions of RNA and proteins)

Question 6

embryo polarity is controlled by coordination of 4 systems:

Answer 6

3 systems to regulate A/P
anterior, posterior, terminal
Dorsal-ventral system

Question 7

name 3 maternal effect genes (one for anterior, posterior, and terminal)

Answer 7

bicoid gene (anterior)
- regulates formation of anterior structures
- bicoid gene product produces a protein gradient

nanos gene (posterior)
- regulates abdomen formation (posterior of egg)
- nanos gene also produces a protein gradient

torso gene (terminal)
- regulation of the poles
- gene production throughout the egg, but only active at the poles

Question 8

in maternal effect gene gradients, what effects do bicoid and nanos have on hunchback and caudal?

Answer 8

bicoid induces hunchback and inhibits caudal

nanos induces caudal and inhibits hunchback

Question 9

___ is the morphogen responsible for Drosophila head structures

Answer 9

bicoid

Question 10

Drosophila dorsal-ventral axis is determined by the gradient of the transcription factor ___

Answer 10

dorsal

Question 11

3 types of segmentation genes in embryo:

Answer 11

1- gap
2- pair rule
3- segment polarity

Question 12

hierarchy of segmentation genes

Answer 12

(maternal genes) –> gap genes –> pair rule genes –> segment polarity genes

Question 13

the A-P axis is divided into broad regions by ___ expression

Answer 13

gap gene

Question 14

further refinement of positional specification and formation of segments: by ___ genes

Answer 14

segment polarity

Question 15

refinement occurs over early development by ___ genes

Answer 15

pair rule

Question 16

homeotic mutants develop a ___ at the particular segment than the usual part (ex: ____)

Answer 16

different body part
Antennapedia

Question 17

homeotic gene complexes of ___ genes also specify body plans in other organism

Answer 17

Hox

Question 18

describe homeotic mutation example of antennapedia

Answer 18

converts antennae of fruit fly into legs

Question 19

describe homeotic mutation example of ultrabithorax

Answer 19

four-winged fruit fly constructed by putting together three mutations in cis regulators of the Ultrabithorax gene (segment T3 converted to T2)