Post on 16-Dec-2015
Dr. Gretchen McCaffrey
Molecular Form and Function
• Email: gmccaff@selway.umt.edu
• 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. 388-397
• Review Cpt 17, pp. 294-304
• Cpt 11, pp. 188-191
• Cpt 45, pp. 896-898
Prokaryotic vs. Eukaryotic Gene Expression
17.2
Control of Gene Expression
E. Coli Human
Eukaryotic Cells Structure correlates with Function
40.3
Different roles for different tissues
Adipose Fat storage
Bone Skeletal support
Muscle Contraction/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 cell Osteoblast (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 cell Osteoblast (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
Plants Animals
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
Single fertilized egg differentiated tissues ?
21.2
Animal Cells
Fertilized Egg
Determined Cells
Differentiated Cells
Animal Development
• DeterminationProgressive restriction of developmental potential causing the possible fate of each cell to become more limited as the embryo develops
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
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 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
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 hormone Nerve 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 factor
binds binds
Intracellular receptor Cell surface receptor
causes causes
Changes in gene expression 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
DevelopmentMaternal cytoplasmic determinants
Asymmetric signalling molecules
Asymmetric transcription factors
Cell specific transcription factors
Cell specific changes in gene expression
Cell fate