Lecture 6: developmental genetics

Question 1

Define and describe the homeobox and distinguish it from the homeodomain.

Answer 1

homeobox is a highly conserved sequence of 180 amino acids. The homeobox contains the homeodomain which is 60 amino acids

Question 2

List major groups of genes that contain the homeobox.

Answer 2

T-box genres
Helix;loop-helix geners
Forhead (Fox) genes

Question 3

What role do homeobox-containing genes play in vertebrate development?

Answer 3

Tbox- mesodermal germ layer and coordinates outgrowth of arm or leg
Helix-loop-helix: homo and heater dimerization and important in myogenesis
Fox: expressing organs

Question 4

Compare loss-of-function mutations to gain-of-function mutations.

Answer 4

Loss of function: posterior to anterior transformations

Gain of function: anterior to posterior transformations

Question 5

Describe the helix-loop-helix and zinc finger transcription factor motifs.

Answer 5

helix loop helix: code for hlh transcription factors; basic regions bind to DNA and homo/heterodimerization

Zinc finger: have zinc ions bound to the polypeptide chains that has finger like projections that can be inserted into the DNA helix

Question 6

List characteristics of Sox genes and WT1.

Answer 6

Sox: high mobility domain and binds to the minor groove of DNA (includes SRY)

WT1: important for the development of the embryonic kidney

Question 7

Describe the function of each of the following sets of genes in the development of the Drosophila body plan: egg polarity genes

Answer 7

maternal effect genes; important in dorsal-ventral and anterior-posterior axes

set up a protein concentration gradient

Question 8

Describe the function of each of the following sets of genes in the development of the Drosophila body plan gap genes

Answer 8

delete adjacent segments

Question 9

Describe the function of each of the following sets of genes in the development of the Drosophila body plan pair rule genes

Answer 9

delete the same part of a pattern in every other segment

Question 10

Describe the function of each of the following sets of genes in the development of the Drosophila body plan segment polarity genes

Answer 10

affect polarity of segment

Question 11

Describe the function of each of the following sets of genes in the development of the Drosophila body plan bithorax complex genes

Answer 11

affects the development of posterior throat and abdominal segments

Question 12

What is a morphogen?

Answer 12

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