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52 Cards in this Set
- Front
- Back
Three tasks in early phase development |
1. Increase the number of cells through cell division 2. Increase the number of cell types of differentiation 3. Generate polarity to allow the establishment of the future body axis |
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Question 1 |
How can an embryo generate different cell types when it starts out as a single cell |
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Question 2 |
Periods and degrees of sensitivity of embryonic organs to teratogens |
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Common Teratogens |
Alcohol Retinoic acid Thalidomide Dietary deficiencies and malnutrition |
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Congenital or External development |
Congenital - genetic changes External - caused by changes in environment |
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Question 3 |
The same set of genes are implicated in embryogenisis and some cancers |
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Zygote |
Fertilized egg |
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Embryo |
Developing organism from fertilization through the formation of differentiated tissues |
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Embryology |
Science which explores embryogenisis (stages: fertilization, cleavage, gastrulation, organogenisis and histogenisis) |
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Developmental Biology |
Studies the life cycle from embryogenisis to postembryonic development to adulthood |
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Ontogeny |
Life cycle of an organism from conception to death |
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Histogenisis |
The formation of tissues from undifferentiated cells |
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Organogenesis |
The process in which endoderm, ectoderm, and mesoderm form the bodies organs |
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Morphogenesis |
The process of an organism developing into it's shape Happens because of cell division, cell growth, changes in membrane composition and secreted products, changes in cell shape, movement, migration and death. |
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Two major developmental biology questions |
1. How does adult organism develop from one cell 2. How does adult organism produce anouther organism |
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Steps of developmental biology |
1. Cell differentiation 2. Morphogenesis 3. Growth 4. Reproduction 5. Evolution 6. Environmental integration |
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Comparative embryology |
Embryonic similarities between different groups of animals |
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Homologous structures |
Organs which are similar because they derive from a common ancestral structure |
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Analogous structures |
Organs which are similar because they perform a similar function |
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Embryogenesis Steps |
1. Fertilization 2. Cleavage 3. Gastrulation 4. Organogenesis 5. Histogenesis |
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Fertilization |
Union of sperm and egg Triggers numerous metabolic reactions that influence further development (Ca+, protein synthesis) |
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Egg |
Large cell, lots of nutrients in the yolk Two poles; animal (close to nucleus) and vegetal (yolk) |
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Sperm |
Has to find and fertilize egg, condensed nucleus and flagellum |
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Development Regulation Enforced by: |
Cytoplasmic maternal determinants & genome of zygote
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Cleavage |
Series of mitotic divisions Blastomeres get smaller to form blastula Blastula will become hollow with a blastocoel filled with fluid Majority of cells now have a predictable fate |
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Pattern of embryonic cleavage is determined by |
Amount of yolk in egg cytoplasm Distribution of yolk in egg cytoplasm |
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Blastomeres |
Cells produced by series of mitotic divisions |
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Fate Map |
Early gastrula stage More pigment on animal side Dorsal lip Dye cells in blastula and watch development |
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Commitment to cell fate |
1. Specification - cells fate is reversible, can be affected by environment changes 2. Determination - irreversible, can not be changed by environment, non visible 3. Differentiation - absolutely irreversible, change in biochemistry, structure, appearance, function |
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Cell potency and fate |
Totipotent - can give rise to a complete individual Pluripotent - can form more structures than their original fate Multipotent - similar to pluripotent but fewer structures |
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Epithelial Cells |
Sheets connected by junctional complexes that act as a barrier Move in harmony Clear polar character from one side to anouther Basal lamina is the foundation that contacts only one surface of the cell |
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Mesenchymal Cells |
Loosely organized and attached Can migrate as individual cells Adhere in 3D clumps Basal lamina may surround the cells Epithelial cells can become mesenchymal |
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Cell to cell interactions |
Induction - one cell or group of cells change the behavior of anouther cell or group of cells Competence - ability of cells to respond to inductive signal Signal transduction - different pathways to obtain induction or competence capabilities |
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Gastrulation |
Series of complex morphogenic movements and activities to form the gastrula Proliferating cells migrate, rearrange, bend, fold and spread |
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Epiboly Intercalation Convergent extension |
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Three germ layers |
Ectoderm Endoderm Mesoderm |
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Ectoderm |
Forms the outer layer of skin and nervous system |
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Endoderm |
Forms the inner lining of the digestive tract and its appendages |
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Mesoderm |
Forms bone and other skeletal structures, muscle, heart, blood vessels, blood cells, kidneys, reproductive organs |
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Organogenesis |
Further movements of germ layers, most cells reach final destination Neurulation - form rudiment CNS Ectoderm forms neural plate --> neural tube Endoderm forms gut rudiment - archenteron Mesoderm - backbone, dorsal muscle, kidneys, heart |
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Histogenesis |
Happens during organogenesis Final cell differentiation |
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Ectoderm forms |
Outer surface, CNS, Neural crest |
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Mesoderm forms |
Dorsal, paraxial, intermediate, lateral, head |
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Endoderm forms |
Digestive tube, pharynx, respiratory tube |
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Germ cells form |
Male sperm and female egg |
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Postembryonic development begins: |
After hatching for animals 9th week till birth in humans |
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Direct development |
Developing animal looks like miniature adult Fetus, juvenile |
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Indirect development |
Developing animal larva goes through series for events and changes (metamorphosis) Tadpoles - frogs Caterpillars - moths Butterflies/ maggots of flies |
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Adulthood |
Production of mature sperm and egg (gametogenesis) Ends with death Mating and parenting Maintaining body Senescence - process of deterioration |