dr. gretchen mccaffrey molecular form and function
TRANSCRIPT
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Dr. Gretchen McCaffrey
Molecular Form and Function
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Molecular Form and Function• Introduction to Development
– Eukaryotic Gene Expression– Cellular Signalling
• Simple Eukaryotic Development: Yeast
• Pattern formation; chick limbs
• Organ identity; floral development
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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
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Reading
• Cpt 21, pp. 388-397
• Review Cpt 17, pp. 294-304
• Cpt 11, pp. 188-191
• Cpt 45, pp. 896-898
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Prokaryotic vs. Eukaryotic Gene Expression
17.2
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Control of Gene Expression
E. Coli Human
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Eukaryotic Cells Structure correlates with Function
40.3
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Different roles for different tissues
Adipose Fat storage
Bone Skeletal support
Muscle Contraction/movement
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Structure/function determined by differential gene expression in different tissues
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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 cell Osteoblast (bone forming cell) Muscle cell
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17.6
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Transcription in eukaryotic cells requires
transcription factors =
Regulatory proteins that binds to DNA and stimulates transcription of specific genes
17.7
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Differential gene expression in different tissues depends upon different transcription factors
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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 cell Osteoblast (bone forming cell) Muscle cell
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Who is this animal and what’s special about her?
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Dolly is special because:
She was cloned from an adult differentiated cell
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Cloning from adult differentiated plant cells
21.5
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Plant vs. Animal Development
Plants Animals
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Plant vs. Animal Development
Plants Animals
Rigid cell walls No cell wall
Energy from sun Moves to find food
Development:
Responds to environment/ Body plan formed early/
opportunistic genetically determined
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Single fertilized egg differentiated tissues ?
21.2
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Animal Cells
Fertilized Egg
Determined Cells
Differentiated Cells
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Animal Development
• DeterminationProgressive restriction of developmental potential causing the possible fate of each cell to become more limited as the embryo develops
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Animal Development
• DeterminationProgressive restriction of developmental potential causing the possible fate of each cell to become more limited as the embryo develops
• DifferentiationStructural and functional divergence of cells as they become specialized during a multicellular organism’s development; dependent on the control of gene expression
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Muscle Cell Development
Precursor cell
Myoblast (muscle stem cell) = determined
Muscle cell = differentiated
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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
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21.8
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Sequential changes in transcription factors
Changes in gene expression
Changes in cell fate
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Single fertilized egg
Two different cells
?
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Single fertilized egg
Two different cells
?
21.9
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• Cytoplasmic determinants– Substances deposited by the mother in the egg
she produces that regulate the expression of genes affecting early development of the embryo
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Development from Two Cells
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Development controlled by:
• Sequential changes in gene expression
• Cell Signalling
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Induction
• Form of cellular signaling during development
• Ability of one group of embryonic cells to influence the development of another.
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Muscle Cell Development
Precursor cellchanges 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
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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
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Cells secrete signals that target specific local or distant cells
11.3
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Chemical signals bind to cell
surface receptor or to intracellular
receptor
45.3
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Same chemical signal received by
different cells different responses
45.4
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Different chemical signals received by same cell different responses
Nerve cell precursor (Determined)
Steroid hormone Nerve growth factor
Hormone secreting cell Neuron
(Differentiated)
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How can signals determine the fate of the cell?
Steroid hormone
binds
Intracellular receptor
causes
Changes in gene expression
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Steroid hormone
45.5
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How can signals determine the fate of the cell?
Steroid hormone Growth factor
binds binds
Intracellular receptor Cell surface receptor
causes causes
Changes in gene expression Changes in gene expression
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Growth factor
11.5
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Single fertilized egg
Two different cells
Asymmetric cytoplasmic determinants lead to cellular specific changes in gene expression
21.9
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DevelopmentMaternal cytoplasmic determinants
Asymmetric signalling molecules
Asymmetric transcription factors
Cell specific transcription factors
Cell specific changes in gene expression
Cell fate