AP Biology

Genetics and Development

ZYGOTE

Fertilized egg of a frog

Specialized Epithelial tissueSee the DIFFERENT shapes?

SpecializationNervous Tissue

Morphogenesis over time

Animal development

Zygote(fertilized egg)

Eight cells Blastula(cross section)

Gastrula(cross section)

Adult animal(sea star)

Cellmovement

Gut

Cell division

Morphogenesis

Observable cell differentiation

Seedleaves

Shootapicalmeristem

Rootapicalmeristem

PlantEmbryoinside seed

Two cellsZygote(fertilized egg)

Plant development

Apoptosis“Programmed Cell Death… it’s in the

DNA.”

Morphogenesis in Plants

Morphogenesis in Animals

Cloning of DollyMammarycell donor

Egg celldonor

Egg cellfrom ovary Nucleus

removedCells fusedCultured

mammary cellsare semistarved,arresting the cellcycle and causingdedifferentiation

Nucleus frommammary cell

Early embryo

Grown in culture

Implanted in uterusof a third sheep

Surrogatemother

Embryonicdevelopment

Lamb (“Dolly”) genetically identicalto mammary cell donor

Embryonic Stem Cells(These have pluripotential – they

can become any type of cell.)

LE 21-9

Embryonic stem cells Adult stem cells

Pluripotentcells

Totipotentcells

Culturedstem cells

Differentcultureconditions

Differenttypes ofdifferentiatedcells

Liver cells Nerve cells Blood cells

Pattern Formation for Plants

Pattern Formation

Pattern Formation

Positional Information

Maternal Effect and Zygote Polarity Animal pole

Vegetalhemisphere Vegetal pole

Point of sperm entry

Animalhemisphere

.

Sperm

Molecules of acytoplasmicdeterminant Fertilization

Nucleus

Molecules of anothercytoplasmic determinant

Unfertilized egg cell

Zygote(fertilized egg)

Mitotic cell division

Two-celledembryo

Cytoplasmic determinants in the egg

.

Early embryo(32 cells)

Signaltransductionpathway

Signalreceptor

Signalmolecule(inducer)

NUCLEUS

Stem cells communicating using ligand molecules

Segment Genes Adultfruit fly

Fruit fly embryo(10 hours)

Flychromosome

Mousechromosomes

Mouse embryo(12 days)

Adult mouse

Hox Genes