Chapter 19- Reporting Flashcards
Who wrote the conditions of existence?
George Cuvier and Charles Bell
● Adaptation through differences
● concentrated on the species distinctions that enable each species to adjust to its surroundings
Conditions of existence
Who wrote the unity of type?
Geoffroy St. Hilaire and Richard Owen
- is critical and secondary to that is evolution
(adaptation) - basic structural agreement that is
present in organisms of the same class and is not influenced by their living styles
Unity of type
- Homologies of embryo and larval structure serves as evidences
Descent with modification
provide the basis for anterior-posterior
axis specification throughout the animal kingdom
Hox genes
demonstrated that the human
HOXB4 gene could mimic the function of its
Drosophila homologue, deformed, when introduced into Dfd-deficient Drosophila embryos
Malicki et al. (1992)
postulated that the Hox gene
expression pattern defines the development of all animals, and that the pattern of Hox gene expression is constant for all phyla
Slack et al. (1993)
They have cataloged four critical
ways in which variation in Hox expression patterns might lead
to evolutionary change.
Gellon and McGinnis (1998)
Four critical ways in which variation in Hox expression patterns might lead
to evolutionary change.
- Changes in the Hox protein-responsive elements of downstream genes
- Changes in Hox gene transcription patterns within a portion of the body
- Changes in Hox gene transcription patterns between portions of the body
- Changes in the number of Hox gene
expressed in the imaginal disc
of the third thoracic segment (wing or haltere are derived)
Ultrabithorax gene (Ubx)
is critical for providing the
proximal-distal axis of the appendages.
Distal-less (Dll) gene
What gene is responsible why snakes are limbless?
HoxC-6 and HoxC-8
is needed both for the polarity of
the limb and for maintenance of the apical ectodermal ridge (AER). Python hindlimb buds lack the AER.
Sonic hedgehog
single hox gene complex per haploid
genome.
Invertebrates
chelicerates possess unique characteristics where their head and
thorax are fused known as __________________
cephalothorax
organisms that have two (2) body
segments, mainly: cephalothorax and abdomen. They have no antennae but have six pairs of appendages. e.g. spiders, scorpions, horseshoe crabs
Chelicerates
arose from neural folds through
the attraction of the neural plate with the
presumptive epidermis
neural cell crest
is a longitudinal ciliated groove
on the ventral wall of the pharynx which produces mucus to gather food particles.
Endostyle
is a pharyngeal organ of uro- chordates,
cephalochordates, and primitive vertebrates. This organ has iodine-concentrating and iodine metabolism activities, and therefore the
endostyle is considered to be homologous to the follicle of these.
Thyroid gland
it is used for specifying dorsal-ventral
polarity, which is used by mammals to activate
inflammatory proteins
Dorsal-cactus pathway
This pathway involves the activation of cell
constituents to perform cellular metabolic processes. A ligand binding to its receptor conforming a signal to channel the secondary messengers inside the cell that gives another signal for the cell to perform a metabolic activity
Tyrosine-Kinase Pathway