Chapter 16 Developmental Genetics

Zygote

Fertilized egg cell formed from the fusion of sperm and egg; totipotent.

Embryo

An early multicellular stage of development following the zygote stage.

Principle of Nuclear Equivalence

Concept that all somatic cells contain the same genetic information.

Cell Determination

Process by which a cell is committed to a specific fate, even before showing specialized features.

Cell Differentiation

Process by which a cell acquires specialized structure and function.

Cytoplasmic Determinants

Molecules (proteins, RNAs) in the cytoplasm that influence early development by regulating gene expression.

Induction

Process where one group of cells influences the development of another through signaling molecules.

Master Regulatory Genes

Genes that control the expression of many other genes to direct development.

Morphogenesis

Process that shapes tissues, organs, and body structures during development.

Pattern formation

Spatial organization of tissues and organs in the developing embryo.

Apoptosis

Programmed cell death that eliminates unneeded or damaged cells.

Hox genes

Subset of homeotic genes that determine the identity of body segments along the anterior-posterior axis.

Homeotic genes

Genes that control the overall body plan by specifying segment identity.

Evo-devo

Evolutionary developmental biology; studies how developmental processes evolve.

Totipotent

Cells that can give rise to all cell types, including extraembryonic tissues.

Pluripotent

Cells that can give rise to nearly all cell types but not extraembryonic tissues.

Steward experiment

Demonstrated that differentiated carrot cells can dedifferentiate and regenerate whole plants.

Gurdon experiment

Showed that nuclei from differentiated frog cells can support development when transplanted into enucleated eggs.

Wilmut & Campbell experiment

Cloning of Dolly the sheep using somatic cell nuclear transfer.

Stem cell

Undifferentiated cell capable of self-renewal and differentiation into specialized cell types.

Embryonic stem cell

Pluripotent stem cell derived from the inner cell mass of a blastocyst.

Adult stem cell

Partially differentiated stem cell found in adult tissues; typically multipotent.

Induced pluripotent stem cell (iPS cell)

Somatic cell reprogrammed to pluripotent state via expression of key transcription factors.

Human reproductive cloning

Creating a genetically identical human organism via nuclear transfer.

Human therapeutic cloning

Creating cloned human cells or tissues for medical treatment, not a whole organism.

Three processes transforming a zygote into a multicellular organism

Cleavage (cell division), differentiation (cells become specialized), morphogenesis/pattern formation (cells organize into tissues and organs).

Origin of cytoplasmic determinants

Cytoplasmic determinants originate in the egg cell; they influence gene regulation by uneven distribution during early development.

Process most relevant to uneven distribution of cytoplasmic determinants

Cleavage (early cell divisions partition cytoplasmic determinants into different cells).

Difference between cell determination and differentiation

Determination = commitment to a fate (comes first), Differentiation = acquisition of specialized structure and function (comes after).