Nematode Caenorhabditis Elegans Develops ______From a Single Fertilized Egg

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?