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Benjamin A. Pierce
GENETICS
A Conceptual Approach
FIFTH EDITION
CHAPTER 22
Developmental Genetics and
Immunogenetics
© 2014 W. H. Freeman and Company
22.1 Development Takes Place Through
Cell Determination
• Totipotent cell: the cell that has the potential to
develop into any cell types
• Determination: a cell becomes committed to a
particular cell fate
• Cloning experiments on plants
• Cloning experiments on animals
22.2 Pattern Formation in Drosophila Serves as
a Model for the Genetic Control of
Development
• The Development of the Fruit Fly
• Egg-Polarity Genes
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–
–
–
–
–
Determination of the dorsal-ventral axis
Determination of the anterior-posterior axis
Segmentation genes
Homeotic genes in Drosophila
Homeobox genes in other organisms
Epigenetic changes in development
22.2 Pattern Formation in Drosophila Serves as
a Model for the Genetic Control of
Development
• Egg-polarity genes:
− Maternal origin: determination of anteriorposterior and dorsal-ventral axes of the
embryo
− Morphogen: protein; its concentration
gradient affects the developmental fate of the
surrounding region.
22.2 Pattern Formation in Drosophila Serves as
a Model for the Genetic Control of
Development
• Determination of the dorsal-ventral axis
− Dorsal gene
• Determination of the anterior-posterior axis
− Bicoid gene, nanos gene, hunchback gene
Concept Check 1
High concentration of which protein stimulates
the development of anterior structure?
a.
b.
c.
d.
Dorsal
Toll
Bicoid
Nanos
Concept Check 1
High concentration of which protein stimulates
the development of anterior structure?
a.
b.
c.
d.
Dorsal
Toll
Bicoid
Nanos
22.2 Pattern Formation in Drosophila Serves as
a Model for the Genetic Control of
Development
• Segmentation genes: control the differentiation
of the embryo into individual segments
• Gap genes: broad region gap differentiation
−Hunchback
• Pair-rule genes: affect alternate segments
• Segment-polarity genes: development of
individual segments
22.2 Pattern Formation in Drosophila Serves as
a Model for the Genetic Control of
Development
• Homeotic Genes in Drosophilia: identity of
segments
• Homeobox Genes in Other Organisms: genes
encoding DNA binding proteins; these proteins
usually play a regulatory rule.
− Hox genes: encode transcription factors that
help determine the identity of body regions
• Epigenetic Changes in Development
Concept Check 2
Mutations in homeotic genes often cause:
a.
b.
c.
d.
the deletion of segments.
the absence of structures.
too many segments.
structures to appear in the wrong places.
Concept Check 2
Mutations in homeotic genes often cause:
a.
b.
c.
d.
the deletion of segments.
the absence of structures.
too many segments.
structures to appear in the wrong places.
22.3 Genes Control the Development of
Flowers in Plants
• Flower Anatomy
• Genetic Control of Flower Development
22.4 Programmed Cell Death Is an
Integral Part of Development
• Apoptosis
− Controlled, programmed cell death
• Necrosis: injured cells dying in an uncontrolled
manner
• Caspases
• Regulation of apoptosis
• Apoptosis in development
• Apoptosis in disease
22.5 The Study of Development Reveals
Patterns and Processes of Evolution
• Common genes in a developmental
pathway
• Evolution through change in gene
expression
22.6 The Development of Immunity Is
Through Genetic Rearrangement
•Antigen: molecules that elicit an immune reaction
•Antibody: proteins that binds to antigens and mark them
for destruction by phagocytic cells
•The Organization of the Immune System
− Humoral immunity: the production of antibodies by
B cells
− Cellular immunity: depends on T cells
− Clonal Selection: primary response, memory
cells, secondary response
22.6 The Development of Immunity Is
Through Genetic Rearrangement
• Immunoglobulin Structure
• The Generation of Antibody Diversity
− Somatic recombination
• Major Histocompatibility Complex Genes
• Genes and Organs Transplants
Genes and Organ Transplants
• Organ transplant requires genetic match
• Immune rejection
– MHC antigens
– The greater the mismatch, the stronger the
immune rejection
– Rejection partially inhibited by drugs
• ABO red blood cell antigens also
important