Ch What do I want to be when I grow up??

Development 1 cell changes into different forms ANIMAL DEVELOPMENT: egg Zygote Fertilization of Gametes Blastula (hollow ball of cells) Gastrula (gut forms) EMBRYO Cells have differentiated

Plant Development Ovuole Pollen GAMETESZYGOTE EMBRYO Seed leaves

Steps of a Cell getting it’s job 1. Determination- its plan for a job Ex. Mesenchymal Stem Cells become Connective Tissue 2. Differentiation- cell actually gets it’s job Ex. Mesenchymal Stem Cells become Muscle, Fat, Tendon (or other connective tissues) 3. Morphogenesis- change shape & cells find their places! Occurs by Cell Division, Apoptosis, & cell movements 4. Growth- Size of organs and body gets bigger

Cell Fate Cell Fate- what kind of cell it will become Blastula cells don’t have cell fate, they become their surroundings Gastrula cells have their cell fate

Plant Cloning Dedifferentiate- carrot root cells (calli) could lose jobs, and become entire new plants Genome Equivalence- all cells in a plant have a full genome (and if treated right, can become any cell in the organism) Great finding for agriculture

Animal Cloning 1. E-nucleate an egg 2. Give it a nucleus from the cell you want 3. Zap! Fuse egg/nucleus together 4. Transplant into Surrogate Mom’s uterus 5. Birth! Out pops a clone

What does this mean for us!??? 1.Clone for Food (GMO- Genetically Modified Organic Material) 2.Preserve Endangered Species 3.Clone Organs 4.Preserve your pet!

Adult Stem Cells PLANTS : Meristems tips of roots/stems (undifferentiated & divide quickly) jobs MAMMALS: in mostly all tissues, replace cells after apoptosis or necrosis (cell death) 300 jobs

Types of Stem Cells 1. Totipotent- cells that can become any part of a new organism A. Zygote cells 2. Multipotent- become only a few types of cells A. Adult Stem Cells 1) Ex. Bone Marrow: a. Hematopoietic stem cells  Red/White Cells b. Mesenchymal stem cells  Bone/Muscle Cells 3. Pluripotent- can form most cells in the body A. Embryonic Stem Cells A. Removed from Blastocyst B. Less likely to be rejected than organ donation or Adult Stem Cells C. Controversial--- Destroys the potential for life? D. PROBLEM FREE: Induced Pluripotent Stem Cells (iPS cells)- skin cells that have been turned into ESC

How Cells Differentiate 1. Cytoplasmic Segregation- empty cells have different fates than the cells full of cytoplasmic determinants 2. Induction- fates determined by the cell’s location and different signals (molecules called “ inducers ”) 1. EX. LIN-3 inducer causes different signals that lead to 3 possible fates in a Nemotode Worm’s vulva 1. Can could be primary vulva precursor, Secondary vulva precursor, or regular skin 2. Travels through signal transduction pathway Polarity

Apoptosis “cuts” out human fetal fingers Ex. Nematode Embyro1,090 cells  951 cells in adult nematode Genes CED-4 and CED-5 expressed in apotosis Day 56Day 35

Organ Identity Genes Encode proteins that create different “whorl” or flower parts groups (petals, sepals, stamens, carpels)

Threshold for inducing “BLUE” fate Threshold for inducing “RED” fate Concentration of Morphogen Each cell has same potential to turn into blue, white, or red Position value is interpreted by the cells and creates a pattern

Positional Information Position information stored in a Morphogen signal Travel to other groups of cells by diffusion

Other Genetic Cues Maternal Effect Genes- transcribed in mother’s ovaries and determine the types of cells that will be on the outside of the egg Ex. Concentrations of Bicoid and Nanos (MEG) cause different effects Segementation Genes- cascades of genes that lead to the cells that are apart of an insect’s segments Hox Genes- tells head cells to make eyes, thorax cells to make wings, etc