- The bicoid gene is one example of a maternal-effect gene. In this mutant, the mother who is homozygous recessive (-/-) is not able to provision the egg with mRNA, which would normally produce a protein in the egg once it is fertilized. The mutation results in embryos with two posterior ends. The cause is a missing molecule, a morphogen that determines which end of the egg develops into the anterior part of the organism. The location of the morphogen is the anterior end of the egg.

- Gap genes set up the segmentation pattern of a larva. Mutations in gap genes produce the loss of specific segments. Gap genes activate pair-rule genes.

- responsible for whole sets of alternate segments or parts of those segments. Mutations in pair-rule genes cause the disappearance of whole sets of alternate segments or parts of those segments. The products of pair-rule genes turn on segment-polarity genes.

Segment-polarity genes

- set up anterior/posterior polarity within each individual segment. Mutations in these genes cause the disappearance of the same half of every segment and its replacement by the mirror image of the remaining half. - Segment polarity genes activate homeotic genes, which determine the developmental fate of groups of cells. When mutated, they cause one part of a body to develop as if it were another part of the body.

Which of the following would be expected if a fly was homozygous for a pair-rule gene mutation?

- The resulting embryo would have only segments 2, 4, 6, and 8.

11.13.2 Pattern Formation in Drosophila, continued Flashcards by Irina Soloshenko

This is a private class.

You need a Pro account to access a Private class
I have an access code

To request access, contact Irina Soloshenko, and ask that they share the class directly with you, using the email address you use for your Brainscape account.

Brainscape's Knowledge GenomeTM

11.13.2 Pattern Formation in Drosophila, continued Flashcards

Brainscape's Knowledge Genome^TM