Ch 18: Genomes and Their Evolution

Question 1

Homeotic genes that control the form of anterior and posterior structures of the body occur in the same linear sequence on chromosomes in Drosophila and mice.

Question 2

Homeotic genes in animals were named Hox genes, short for ________-containing genes, because homeotic genes were the first genes found to have this sequence.

Answer 2

homeobox

Question 3

Developmental biologists have found that in addition to homeotic genes, many other genes involved in development are highly ________ from species to species. These include numerous genes encoding components of signaling pathways.

Answer 3

conserved

Question 4

In some cases, small changes in regulatory sequences of particular genes cause changes in gene expression patterns that can lead to major changes in body form. For example, the differing patterns of expression of the Hox genes along the body axis in a crustacean and an insect can explain the variation in the number of leg-bearing segments among these closely related animals

Question 5

How genes can turn on different developmental processes. Both caterpillars and see urchins have Hox genes, but very different body forms.

Question 6

Changes in sequence of Hox genes can change an organism’s body plan.