Ch 16/17 quiz Flashcards
What leads to different cell types in an organism?
Differential gene expression
What is responsible for the transformation of a zygote into an organism?
Cell division, cell differentiation and morphogenesis
What is morphogenesis?
The physical processes that give an organism its shape, the development of the form of an organism and its structures
What are cytoplasmic determinants?
Unevenly distributed substances in the egg that influence early development such as mRNA, proteins and organelles
Why is uneven distribution if cytoplasmic determinants important?
After fertilization, divisions distribute the zygotes unevenly distributed cytoplasm to different cells, exposing different nuclei to different determinants. These determinants regulate gene expression
What is induction?
Signals/growth factors secreted by neighboring cells that cause changes in target cells
What are the major sources of developmental information?
- The egg’s cytoplasm-uneven distribution of determinants
2. The environment around a cell-this becomes more important as number of embryonic cells increase, induction
What is determination?
The term coined by biologists that means the unseen events that lead to observable differentiation of a cell. This is irreversible
What gives a cell its characteristic structure and function?
Tissue specific proteins-found only in specific cell types
What is the most important factor in maintaining gene expression?
transcription
What are examples of differentiated cells?
- Liver cells specialize in making albumin
- lens cells specialize in making crystallin
- Skeletal muscles have high concentrations of muscle-specific versions of contractile proteins myosin and actin
What are myoblasts?
muscles cells that appear to be the same as embryonic cells but have undergone determination. The churn out large amounts of muscle-specific proteins and fuse to form skeletal muscle cells
What is myoD?
A master regulatory gene that encodes the protein MyoD, a transcription factor that binds to specific control elements in the enhancers of various target genes and stimulates their expression. MyoD also also stimulates expression of myoD, helping to maintain a differentiated state. MyoD coordinately controls cells
How does commitment occur in cell differentiation?
Master regulatory genes and secondary transcription factors activate genes
What is apoptosis?
Programmed cell death. Occurs in cells that are infected, damaged or at the end of their lifespan. Cellular agents chop up DNA and fragment the organelles and the cells parts are packaged into vesicles. This protects surrounding cells from being damaged
What is blebbing?
A cell becoming multilobed as a part of apoptosis
Hiw is apoptosis triggered?
Signal transduction pathways activate a cascade of apoptotic proteins and enzymes that perform apoptosis
Where is apoptosis believed to evolve from?
early eukaryotes
Why is apoptosis important?
It is essential for normal development of the nervous system and normal morphogenesis of hands/paws
What is pattern formation?
The process of cytoplasmic determinants and inductive signals contributing to the development of spatial organization
What is positional information?
Molecular cues that control pattern formation provided by cytoplasmic determinants and inductive signals that tell a cell its location relative to the body axes and neighboring cells and determine how the cell and its offspring will respond to future molecular signals
How early does an egg provide positional information?
before fertilization
What are homeotic genes?
Genes that control pattern formation in the late embryo, larva and adult
What are embryonic lethals?
mutations with phenotypes that cause death at the embryonic or larval stage
What are maternal effect genes?
A gene that, when mutant in the mother, results in a mutant phenotype in the offspring regardless of the offsprings own genotype
What are egg-polarity genes?
Genes that control the polarity/orientation of the egg, and consequently the drosophila
What is a bicoid?
A maternal effect gene essential for setting up the anterior end of a fly
What are morphogens?
Gradients of substances that establish and embryo’s axes and other features of its form, apart of he morphogen gradient hypothesis
What is genomic equivalence?
The concept that all cells have the same genes
What is organismal cloning?
an organism or organisms that develops from a single cell without meiosis or fertilization producing one or more organisms genetically identical to the “parent” that donated the single cell