Dr. Gretchen McCaffrey Molecular Form and Function

Office hours: Wed 2-3pm NS 207 Thurs 12-1pm NS207

Molecular Form and Function Introduction to Development –Eukaryotic Gene Expression –Cellular Signalling Simple Eukaryotic Development: Yeast Pattern formation; chick limbs Organ identity; floral development

Major points The process of plant development occurs in response to the environment while the process of animal development is genetically determined The process of development is controlled by sequential changes in gene expression and by cell signalling

Reading Cpt 21, pp Review Cpt 17, pp Cpt 11, pp Cpt 45, pp

Prokaryotic vs. Eukaryotic Gene Expression 17.2

Control of Gene Expression E. ColiHuman

Eukaryotic Cells Structure correlates with Function 40.3

Different roles for different tissues AdiposeFat storage BoneSkeletal support MuscleContraction/movement

Structure/function determined by differential gene expression in different tissues

Gene 1: Encodes RNA Polymerase Gene 2: Encodes protein that allows formation of fat droplets Gene 3: Encodes collagen; protein that hardens to form bone Gene 4: Encodes myosin; protein needed for muscle contraction _______________________________________________ Adipose cellOsteoblast (bone forming cell)Muscle cell

17.6

Transcription in eukaryotic cells requires transcription factors = Regulatory proteins that binds to DNA and stimulates transcription of specific genes 17.7

Differential gene expression in different tissues depends upon different transcription factors

Gene 1: Encodes RNA Polymerase Gene 2: Encodes protein that allows formation of fat droplets Gene 3: Encodes collagen; protein that hardens to form bone Gene 4: Encodes myosin; protein needed for muscle contraction _____________________________________________ Adipose cellOsteoblast (bone forming cell)Muscle cell

Who is this animal and what’s special about her?

Dolly is special because: She was cloned from an adult differentiated cell

Cloning from adult differentiated plant cells 21.5

Plant vs. Animal Development PlantsAnimals

Plant vs. Animal Development PlantsAnimals Rigid cell wallsNo cell wall Energy from sunMoves to find food Development: Responds to environment/Body plan formed early/ opportunisticgenetically determined

Single fertilized egg differentiated tissues ? 21.2

Animal Cells Fertilized Egg Determined Cells Differentiated Cells

Animal Development Determination Progressive restriction of developmental potential causing the possible fate of each cell to become more limited as the embryo develops

Animal Development Determination Progressive restriction of developmental potential causing the possible fate of each cell to become more limited as the embryo develops Differentiation Structural and functional divergence of cells as they become specialized during a multicellular organism’s development; dependent on the control of gene expression

Muscle Cell Development Precursor cell Myoblast (muscle stem cell) = determined Muscle cell = differentiated

Muscle Cell Development Precursor cell changes in transcription factors = changes in gene expression Myoblast (muscle stem cell) = determined more changes in transcription factors = more changes in gene expression Muscle cell = differentiated

21.8

Sequential changes in transcription factors Changes in gene expression Changes in cell fate

Single fertilized egg Two different cells ?

Single fertilized egg Two different cells ? 21.9

Cytoplasmic determinants –Substances deposited by the mother in the egg she produces that regulate the expression of genes affecting early development of the embryo

Development from Two Cells

Development controlled by: Sequential changes in gene expression Cell Signalling

Induction Form of cellular signaling during development Ability of one group of embryonic cells to influence the development of another.

Muscle Cell Development Precursor cell changes in transcription factors = changes in gene expression Myoblast (muscle stem cell) = determined more changes in transcription factors = more changes in gene expression Muscle cell = differentiated

Muscle cell Development Precursor cell Requires growth factors to continue dividing Myoblast (muscle stem cell) = determined Cell division stops Muscle cell = differentiated No cell division

Cells secrete signals that target specific local or distant cells 11.3

Chemical signals bind to cell surface receptor or to intracellular receptor 45.3

Same chemical signal received by different cells different responses 45.4

Different chemical signals received by same cell different responses Nerve cell precursor(Determined) Steroid hormoneNerve growth factor Hormone secreting cell Neuron (Differentiated)

How can signals determine the fate of the cell? Steroid hormone binds Intracellular receptor causes Changes in gene expression

Steroid hormone 45.5

How can signals determine the fate of the cell? Steroid hormone Growth factorbinds Intracellular receptor Cell surface receptorcauses Changes in gene expression

Growth factor 11.5

Single fertilized egg Two different cells Asymmetric cytoplasmic determinants lead to cellular specific changes in gene expression 21.9

Development Maternal cytoplasmic determinants Asymmetric signalling molecules Asymmetric transcription factors Cell specific transcription factors Cell specific changes in gene expression Cell fate

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