dev gen exam 1

• Conditional specification 


  The ability of cells to achieve their respective fates by interactions with other cells. What a cell becomes is in large measure specified by paracrine factors (signals) secreted by its neighbors as well as

  • cell-cell contact (juxtacrine factors)
  • mechanical stress
• Syncytial specification 


  The interactions of nuclei (multiple nucleus) and transcription factors, which eventually result in cell specification, that take place in a common cytoplasm, as in the early Drosophila embryo.
• Cloning a mammal using nuclei from adult somatic (body) cells as seen in Dolly the sheep proves the first postulate of differential gene expression, that Every somatic cell nucleus of an organism contains the complete genome. Alternatively, we can say the DNA of the all differentiated cells are identical.
• From differentiated fibroblast to induced pluripotent stem cell with four transcription factors, the “Yamanaka factors” 
• Differential gene expression is A basic principle of developmental genetics: In spite of the fact that all the cells of an individual body contain the same genome, the specific proteins expressed by the different cell types are widely diverse. Differential gene expression, differential nRNA processing, differential mRNA translation, and differential protein modification all work to allow the extensive differentiation of cell types.


  Differential gene expression can be due to Epigenetics
• Differential splicing can process the same pre-mRNA into different mRNAs by selectively using different exons.


  what do the V shaped lines in this diagram represent? Alternative splicing patterns

  A) intron

  B) exons

  
• what example of alternative pre-mRNA splicing is this?

  cassette exon type II can be used as an exon or removed as intron

  A) cassette exon

  
• what example of alternative pre-mRNA splicing is this?

  either of the 2 exons 8 or 9 are chosen to make the mature mRNA, resulting in different mature mRNA

  A) mutually exclusive

  
• what example of alternative pre-mRNA splicing is this?

  the exon has 2 splice sites, 5' upstream and 3' downstream. mature mRNA retains the whole exon or only one of the splice sites

  A) 5' splice

  
• what example of alternative pre-mRNA splicing is this?

  the exon has 2 splice sites, 5' upstream or 3' downstream. mature mRNA retains the whole exon or only one of the splice sites.

  A) 3' splice

  
• Development biology seeks to elucidate the cellular and molecular events that drives changes of cells, tissues and organs over timescale from fertilization to hatching (or birth).
• embryology: The study of animal development
• Regeneration and Metamorphosis: Some animals can regenerate several parts. 

  Example: Zebrafish heart/tail; Salamander

  Many species undergo metamorphosis, changing from one into another: Example: Example: Caterpillar into a butterfly.
• development: Multicellular organisms arise by a process of progressive change 
• zygote: The development of multicellular organism begins with a single cell and then completes the process of fertilization (egg and sperm unites)
• Indeterminate growth: Plant growth is indeterminate, the capacity of growth throughout the life span. Plants also shows extraordinary capacities for development.
• cell Differentiation 
The process by which an unspecialized cell becomes specialized into one of the many cell types that make up the body.

  • Example: a brain cell (neuron) is different than blood cell in structure, protein composition and function
• Specification : The first stage of commitment of cell or tissue fate during which the cell or tissue is capable of differentiating autonomously (i.e., by itself) when placed in an environment that is neutral with respect to the developmental pathway. At the stage of specification, cell commitment is still capable of being reversed.



  Determination: The stage of commitment following specification; the determined stage, assumed irreversible, is when a cell or tissue is capable of differentiating autonomously even when placed into a non-neutral environment.
• • cell specification: when cells are placed into neutral media, muscle cells will turn into muscle, and brain cells will turn into neuron
  • cell specification is labile. cells can still change their fate based on interactions with surrounding cells
  • cell determination: muscle cell will turn into muscle cell when placed into media of neurons

  
• Teratogens: Greek, “monster-formers.” Exogenous agents that cause disruptions in development resulting in teratogenesis, the formation of congenital defects. Teratology is the study of birth defects and of how environmental agents disrupt normal development
• why study developmental biology? Understanding how organisms grow and develop can provide insights into human health, evolution, and the treatment of diseases.
• this is an example of what specification? conditional

  
• this is an example of what specification? syncytial

  
• define and explain the differences between cell differentiation and cell determination

  
  

  Cell determination: process in which embryonic stem cells commit to one specialized function

  
  

  Cell differentiation: process in which cells develop their specialized shapes and functions

  
  

  -determination has to happen for differentiation to occur
• The histone “tails” that extend from the core are the sites of acetylation (on) and methylation (off), which may disrupt or stabilize, respectively the formation of nucleosome assemblages. 
• Histone methyltransferases add methyl groups to the histones


  histone deacetylases which take acetyl groups off the histones
• Both Histone methyltransferases and histone deacetylases modifications promote the stability of the nucleosome and the tight packing of DNA, thereby repressing gene expression in these regions of DNA methylation.
• The genetic elements regulating tissue-specific transcription can be identified by fusing reporter genes to suspected enhancer regions of the genes expressed in particular cell types. example: GFP gene in zebrafish
• Differential gene expression due to Epigenetics

  • Epigenetics is the study of heritable phenotype changes that do not involve alterations in the DNA sequence.
  • Epigenetics most often involves changes that affect gene activity and expression resulting from external or environmental factors.