Lect. 10 - Dev. Genetics II

Question 1

Hierarchy order of genes in drosophila development

Answer 1

Egg polarity genes (maternal effect genes), segmentation genes, homeotic genes

Question 2

maternal effect genes aka egg polarity genes

Answer 2

important in the establishment of the dorsal-ventral and anterior posterior axes in the fruit fly

Question 3

egg polarity genes that establish the ventral-dorsal axis include:

Answer 3

dorsal, cactus, toll

Question 4

egg polarity genes that establish the anterior-posterior axis include:

Answer 4

bicoid, nanos, hunchback

Question 5

why are egg polarity genes also called maternal effect genes?

Answer 5

even though their mRNAs migrate to the eggs and are translated after fertilization, they are transcribed into mRNAs in the ovary BEFORE fertilization

Question 6

how do egg polarity genes work?

Answer 6

by setting up protein concentration gradients

Question 7

morphogen

Answer 7

a protein that varies in concentration and causes different developmental responses as a result of the concentration differences

Question 8

Where are dorsal, cactus, and toll genes expressed?

Answer 8

in the ovary

Question 9

cactus protein

Answer 9

binds dorsal protein and traps it in the cytoplasm

Question 10

toll protein

Answer 10

leads to the degradation of the cactus protein, allowing dorsal protein to move into the nuclei of the ventral cells

Question 11

Nanos Protein

Answer 11

expressed in the ovary; regulates expression of genes responsible for posterior structures; inhibits translation of hunchback mRNA

Question 12

Bicoid Protein

Answer 12

express in ovary; regulates expression of genes responsible for anterior structures and stimulates hunchback

Question 13

segmentation genes

Answer 13

transcribed after fertilization; Gap genes, pair-rule genes, segment-polarity genes

Question 14

what regulates the segmentation genes?

Answer 14

bicoid and nanos protein gradients

Question 15

gap genes

Answer 15

delete adjacent segments

Question 16

pair-rule genes

Answer 16

delete sam part of patter in every other segment

Question 17

segment-polarity gene

Answer 17

afftect polarity of segment

Question 18

homeotic genes

Answer 18

determines the identity of individual segments; expressed after fertilzation; contain homeobox; antennapedia and bithorax complex

Question 19

what activates the homeotic genes?

Answer 19

concentration of products of gap, pair-rule, and semgnet-polarity genes

Question 20

antennapedia complex

Answer 20

affects development of head and thorax

Question 21

bithorax complex

Answer 21

affects development of posterior thorax and abdominal segments