Download Chapter 19 Notes

Chapter 19 Notes
Nematode Caenorhabditis elegans develops __________________ from a single
fertilized egg
All _____________________ develop according to molecular mechanisms that are
fundamentally very similar
•
This suggests that these mechanisms evolved very early on
•
6 Mechanisms
– _______________________
– _______________________
– _______________________
– _______________________
– _______________________
– _______________________
Cell Movement
 Cells can move by _______________ along with adhesion molecules.
• Some tissues have most of volume taken up by intercellular spaces filled with
matrix of polysaccharide chains.
• Migrating cells traverse by binding _______________________________.
• The movement of cells involves _______________ and loss of __________
• Involves _____________ interactions and ________________ interactions
• Cell migration is largely a matter of changing ____________________
Induction
Induction: __________________________________________________________
___________________________
Mosaic development vs. regulative development
– mosaic – _______________________________________________
______________________
– Regulative – _______________________________________________
___________________________
• Cell-cell interactions can be demonstrated by separating the cells of an early
blastula and allowing them to _____________________________
• Under these conditions __________________ cells develop features of
ectoderm and ________________________ cells develop endoderm
– Mesoderm features are not seen
• If the cells from opposing poles are placed near each other, then ____________
features are seen
• The interaction of two cell types triggers a ____________________________
• Induction - Figure 19.10 Development of the vertebrate eye by induction.
– The eye develops as an _________________________ called the optic
stalk that grows out until it contacts the ectoderm. This contact induces the
formation of a lens from the _____________________
Organizers: groups of cells that
produce
___________________________ that
convey ______________________ to
other cells
• They have a profound influence on
the ________________________
• Morphogen: signal molecule
have different effects
___________________
Determination
• Mammalian cells are ____________ - potentially capable of _______________
___________________.
• The vertebrate egg is _________________________ as well as its shape. All
cells of the _____________ are the same
• If separated, any cell can produce a ____________________.
• This has been used to create 8 identical offspring (cattle)
– If cells from two different eight-cell embryos are combined, a normal
individual results ________________.
– Mammalian cells begin to differentiate after the ______________________.
– ______________ is the commitment to a specialized developmental path.
– ______________ is the cell specialization that occurs at the end of the
developmental path.
– Determination is _________________.
– Given proper technique, fate of fully differentiated cell can be altered.
– Gene regulatory proteins initiate ____________________
– When genes encoding these proteins are activated, one of their effects is to
reinforce their own activation
– Cells in which a set of regulatory genes have been activated may not undergo
differentiation, but once the “switch” is thrown, the cell us fully committed to its
future development.
This experiment, the first
successful cloning of a mammal
shows that a differentiated adult
cell can be used to drive all of
development
Animals use _________
_________________ to
determine the basic
pattern of body
compartments and
overall architecture of
the body.
Body organization in
the developing
Drosophila embryo
• Drosophila egg acquires initial asymmetry as a result of maternal mRNA.
• Fertilization causes mRNA to be translated into bicoid protein.
 establishes anterior end of embryo
 if injected into posterior end of normal embryos, head and thorax
will develop at that end
• Within three hours after fertilization, orchestrated ________________ gene
activity produces fly ____________________.
– Gene activation depends on free diffusion of _______________ through
______________________.
• After pattern formation has been established in Drosophila, a series of homeotic
genes determine the forms these segments will take.
– code for proteins that function as __________________
• Mutations in homeotic genes can cause normal body parts in unusual
places.
– typically contain the __________________
• also been found in mice and humans
Homeobox
• A 180 nucleotide sequence that codes for a 60 amino-acid DNA-binding peptide
called the ________________
• Contain ______________________ which ensure that developmentally related
genes are transcribed at the appropriate time
• Bicoid and engrailed genes in the homeobox
Apoptosis
• Not all cells produced are destined to survive
• Cells between ________________________ die
• _______________ – cells that die due to injury typically swell and burst,
releasing their contents into the extracellular fluid
• _______________ – programmed cell death
• All animal cells appear to posses “death program”
• Examples?