22. Development & Segmentation

Question 1

Regulative development

Answer 1

Cells fate is not pre-determined, can change through interactions with cells or environment

Question 1

Mosaic development

Answer 1

Cells fate is pre-determined by factors inherited at division

Question 2

Main limitations of primary mutant screening?

Answer 2

Reduntant genes and pleiotropic genes are not detected

Question 3

Molecule that binds to a receptor

Answer 3

Ligand

Question 4

Mutation that causes hypomorph to appear more mutant

Answer 4

Dominant enhancer

Question 5

Mutation that causes hypomorph to appear more like wild type

Answer 5

Dominant suppressor

Question 6

What is a modifier screen?

Answer 6

A technique to screen for mutants based on the severity of pre-existing phenotypes and their sensitivity

Question 7

Pleiotropic genes

Answer 7

Genes required for morethan one developmental pathway

Question 8

What is the goal of RNA hybridization?

Answer 8

To determine when and where a gene’s transcripts are accumulated (to define tissues)

Question 9

Genetic mosaic

Answer 9

Individuals with cells of more than one genotype

Question 10

What is true for genes a and b in ordering?

Answer 10

Gene a affects expression of gene b, but not the opposite.

Question 11

Morphogen

Answer 11

Substance that defines cell fates in a concentration-dependent manner

Question 12

Two major maternal-effect genes

Answer 12

Bicoid (bcd) and Nanos (nos)

Question 13

Develops anterior segments

Maternal-effect genes

Answer 13

Bicoid

Question 14

Develops posterior

Maternal-effect genes

Answer 14

Nanos

Question 15

Three classes of zygotic segmentation genes

Answer 15

Gap genes
Pair-Rule genes
Segment-polarity genes

Question 16

Anterior gap gene

Answer 16

hunchback (hb)

Question 17

Middle gap gene

Answer 17

Krüppel (Kr)

Question 18

Posterior gap gene

Answer 18

knirps (kni)

Question 19

Pair-rule genes that respond to maternal and gap gene input

Answer 19

Primary pair-rule gene

Question 20

Pair-rule genes that respond to other pair-rule genes

Answer 20

Secondary pair-rule gene

Question 21

Purpose of pair-rule genes?

Answer 21

To further segment into parasegments. Refine from broad domains to stripes