Topic 13: Genetics of Development

Question 1

Homeotic mutants+ex (2)

Answer 1

One part of the body is transformed to resemeble another part
ex: Antennapedia- legs instead of antennas

Question 2

Thorax

Answer 2

3 distinct region

Question 3

Adbomen

Answer 3

8 distinct region

Question 4

Morphogen (2)

effects are+ establish

Answer 4

• Molecules whose effects are concentration dependent
• establish the pattern of tissue development and body plan formation

Question 5

Morphogen gradients ultimately determine

Answer 5

Hoax gene (homeotic gene) expression

Question 6

Hox genes control the

Answer 6

identity of segments and appendages

Question 7

Hox genes encode

Answer 7

transcription factors

Question 8

Genectic toolkits (4)

What it includes+ responsible for+encodes+highly

Answer 8

• Hox genes+ genes encoding regulators of hox genes
• set of genes responsible for the regulation of animal development
• mostly encode cell signalling proteins and TF
• highly conserved across diverse species of animals

Question 9

List in order, the classes of toolkit genes involved in regulating the anteroposterior body axis in drosophila (5)

Answer 9

1. Maternal effect genes
2. Gap genes
3. Pair-rule genes
4. Segment-polarity genes
5. Hox genes

Question 10

Maternal-effect genes (6)

what it is+before fertiliz+help establish+ bicoid/Nanos+ fertiliz+encode

Answer 10

• genes expressed in the mother
• Needed before fertilization just to set up the egg
• Help establish anterior and posterior end of the eventual animal
• Bicoid and Nanos mRNA are tethered to the anterior and posterior ends of the unfertilized eggs
• Upon fertilization, the proteins are expressed and form a gradient
• Bicoid and nanos encode TF that regulate expression of the next set of genes

Question 11

Mutant phenotypes of maternal effect genes depend only on the

Answer 11

genotype of the egg parent

Question 12

Maternal effect genes determines

Answer 12

major body axis

Question 13

Segments genes which are— affect the —- of Drosophila body segments

Answer 13

• Gap genes, pair-rule, segment-polarity genes
• number and organization

Question 14

Gap genes

Answer 14

• devide the embryo into broad regions

Question 15

Mutations in gap genes lead to

Answer 15

large gaps in segmentation

Question 16

Pair-rule genes affect (3)

development of+promote+define

Answer 16

• the development of pairs of segments
• promote the formation of alternate body segments
• define individual segments

Question 17

Segment polarity genes

Answer 17

• affect the organization of individual segments

Question 18

Muations in segement polarity genes lead to

Answer 18

defects in segment polarity

Question 19

Hox genes determine the

Answer 19

identity of a structure or segment

Question 20

Hox genes are expresed in restricted regions in the embryo that give rise to

Answer 20

the coresponding adult body parts

Question 21

How do Hox genes control the expression of other genes??

Answer 21

They bind to cis acting regulatory elements of other genes to activate or repress them

Question 22

How are genes expressed in precise patterns at different times in drosophilla

Answer 22

TF interact with cis-regulatory elements to control expression over space and time

Question 23

Gap genes are activated by (3)

Answer 23

• maternal effect protein, bicoid a TF localized to the anterior
• Bicoid protein binds to three sites near the hunchback promotor to activate expression
• threshold level of bicoid protein (3 protein bind to 3 DNA element to recruit TF and turn on transcrip.) is required for hunchbck expression

Question 24

Diff TF binding to enhancer in percise combination and percise concentration

Answer 24

regulate gene expression such as Eve

Question 25

Hox gene is ----- through ------ and turn on -----

Answer 25

1. conserved 2. evolution 3. similar body structure in different species