Chapter 23 - Developmental Genetics
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Study Outline
I. Overview of Animal Development
A.
The generation of a body pattern depends on the positional information
that each cell receives during development
B.
The study of mutants with disrupted developmental patterns has identified
genes that control development
C.
Animal development occurs in four overlapping phases
II. Invertebrate Development
A.
A.The early stages of embryonic development determine the pattern of structures in
the adult organism
B.
The gene products of maternal effect genes are deposited asymmetrically into the
oocyte and establish the anteroposterior and dorsoventral axes at a very early stage
of development
C.
Gap, pair-rule, and segment-polarity genes act sequentially to divide the Drosophila
embryo into segments
D.
The expression of homeotic genes controls the phenotypic characteristics of
segments
E.
The developmental fate of each cell in the nematode Caenorhabditis elegans is
known
F.
Heterochronic mutations disrupt the timing of developmental changes in C. elegans
III. Vertebrate Development
A.
Researchers have identified homeotic genes in vertebrates
B.
Genes that encode transcription factors also play a key role in cell differentiation
IV. Plant Development
A.
Plant growth occurs from meristems formed during embryonic development
B.
Plant homeotic genes control flower development
V. Sex Determination in Animals and Plants
A.
In Drosophila, sex determination involves a regulatory cascade that includes
alternative splicing
B.
In C. elegans the ratio of X chromosomes to sets of autosomes initiates a regulatory
cascade that determines sex
C.
In mammals, the Sry gene on the Y chromosome determines maleness
D.
In sexually dimorphic plants, the male plant is usually heteromorphic