Gap and Pair-rule Genes - L15

Question 1

What happened in Bicoid mutant experiments?

Answer 1

Injection of wild-type egg cytoplasm from head region into a bicoid mutant egg generates head segements

Question 2

What does Bicoid mRNA do in Bicoid proteins?

Answer 2

Forms a concentration gradient.

mRNA is translated after fertilisation to form an anterior-posterior Bicoid protein gradient.

Question 3

Bicoid protein is a….

Answer 3

MORPHOGEN.

Specifies anterior-posterior axis.

Question 4

In maternal gene gradients what does nano suppress?

Answer 4

Nano suppresseds translation of maternal hunchback mRNA in posterior.

Question 5

In maternal gene gradients what effect does Bicoid have?

Answer 5

Promotes production of embryos own hunchback protein in anterior.

Question 6

Is nanos a morphogen?

Answer 6

NO

Question 7

Bicoid also inhibits the translation of what?

Answer 7

Caudual proteins in the anterior.

SO, forms a posterior-anterior gradient.

Question 8

How do maternal mRNA become distributed?

Answer 8

GURKEN MRNA

from mother is translated into posterior and protein binds to torpedo receptor in posterior follicle cells.

Question 9

What does binding to the torpedo receptor cause?

Answer 9

Causes posterior cells to produce a signal that rearranges micro tubules in egg cytoskeleton.

Question 10

Posterior localisation of what is needed for nanos mRNA in posterior?

Answer 10

oskar RNA

Question 11

Movement of gurken mRNA is associated with what?

Answer 11

movement of nucleus to establish dorsal axis

Question 12

What are the different types of genes in development?

Answer 12

Maternal Genes
Gap Genes
Pair-rule Genes
Segementation Genes 
Selector Genes

Question 13

Mutations in gap genes commonly cause what?

Answer 13

Segment deletion

Question 14

Gap genes are the first zygotic genes to be expressed along the AP axis and code for transcription factors.

Answer 14

TRUE.

Question 15

Name an example of a Gap gene

Answer 15

Hunchback

Question 16

What does hunchback do?

Answer 16

Activates and represses other gap genes such as knrips, kuppel and giant.

Question 17

Pair rule genes are expressed in what alternate parasegments?

Answer 17

Even-skipped (blue) -odd parasegments
Fushi Tarazu (red)- even parasegments

Question 18

How do you make even-skipped stripe?

Answer 18

.bcd and hb activate eve gene
.Giant and kruppel repress eve gene
.Ant.border set by giant protein and posterior set by Kruppel

Question 19

An example of a segment polarity gene and where it is produced

Answer 19

Engrailed, produced in anterior regent of each parasegment

Question 20

What activates engrailed gene expression?

Answer 20

Pair-rule genes

Question 21

What is the purpose of engrailed gene expression?

Answer 21

Helps to define parasegment borders, confining cells and descendants into compartments.