Topic 13 Flashcards
body parts where they werent supposed to be or duplications
homeotic transformations
some of the first gene promoters to be explored
homeotic genes
ontogeny recapitulated phylogeny
biogenetic law
ontogeny:
Recapitulates:
Phylogeny:
:Development
:replays
:evolutionary history
development proceeds from general to specific
- an embryo can be anything
- to preserve early stages
Von Baer’s Law
changes in timing of development
Heterochrony
-2 forms
elder form- exageration of adult morphologies
-something added to life stage
Paramorphosis
Child form- retention of juvenile morphology
Paedomorphosis
Mature past adulthood and demonstrate hitherto unseen traits ( late offset)
Hypermorphosis
- thought irish elk
- different growth in our structures (head)
- acromegaly
Part grows faster than in ancestors
Acceleration
-narwhal tusk, fiddler crab, nectar spurs
onset of growth earlier
predisplacement
-ex/ meckels cartilage in birds
differential growth of structures
allometry-type of hypermorphism
beak on some birds
parts grow at same rate
isometry
early offset, growth halts early
progenesis
ex/salomanders w juvenile hands
aphids mature before wings form some fish
part grows slower than in ancestors
neoteny
-ex/humans increased skull allometry
onset of growth later than ancestor
postdisplacement
-mammel meckels cartlage forms later than in ancestors (alligator)
control the patterning of body structures, control identity of segments in all metazoans.
Hox genes
missing thymus and pythiroid glands, abnormal ears, nose mouth and throat-kind of lke anntenipedia (hox gene)
Digeoirge syndrom
changes to ears and lower jaw is an upper jaw
Ariculocondylar syndrome
sonic hedgehog causes mirror image dupication to face
janice effects
-most of these are further down from the homeotic gene
if it turns on in leg segment you get legs instead of anntenae
antennapedia
a group involved in positioning of different cells
MADS-box AG
have three classes of transcription factors- A, B, and C
dicots
mutation to the AP3 gene in flowers
Arabidopsis
controls eye development
Pax6
structures may be homologous at one level, but not at another
Biological Homology concept
encodes a transcription factor that governs development of body outgrowths
Distalless
example of distalless
- causes small or missing eye in drosophila
- mammal equivalent is Pax6
Eyeless
genes may have multiple enhancers
Regulatory Modularity
different parts can evolve separately
Modularity
homologous genes within a species
Paralogous
homologous genes between a species
Orthologous
One copy gains a new function, has to occur before one copy loses function
-Ohnom
Neofuntionalization
duplicate becomes specialized for a subset of the original genes functions, both gene copies would be expected to evolve
subfunctionalization
can form many different types of cells
pleuripotent cell
twisted wing parasites
strepsiptera
