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37 Cards in this Set
- Front
- Back
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What is a gene control region?
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All DNA sequences required to initiate transcription. Contains the promoter, regulatory proteins, and regulatory sequences.
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What do regulatory sequences and regulatory proteins do?
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Regulatory proteins (activators) bind to regulatory sequences (enhancers) and help initiate transcription - gene expression.
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How does the mediator in the pre -initiation complex aid initiation?
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By regulationg the CTD kinase TF11H.
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What genes are needed to produce a multicellular animal, beyond those necessary for a solitary cell?
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- Transmembrane molecules, used for cell adhesion and cell signaling
- Gene regulatory proteins which are much more abundant in humans than other species. |
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5 main structures of gene regulatory proteins?
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Helix-Turn-Helix -
Homeodomain - Helix-loop-helix Zinc fingers Leucine Zippers |
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Where are the instructions needed to produce a multicellular animal contained?
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Non-Coding, regulatory DNA that is associated with each gene. Theis regulatory DNA is/are enhancers where regulatory proteins can bind. And it is the concentration, combination, and location of these proteins, specifically that give these instructions.
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What are the types of activation of the regulatory proteins?
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-Control of protein synthesis
-Ligand binding -Phosphorylation -Protein-protein combinations -Protein conformation changes -Protein location ie transport into the nucleus. |
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What are the pathways that lead to production of specific transcription factors?
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STAT, JAK, and Ras pathways.
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T or F - The location of the enhancer relative to the promoter is critical.
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F - it is not critical.
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What are some of the combinational controls of gene expression?
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- Interaction of general & specific transcription factors
-Co-activators & activator interactions - Interactions of repressors and activators. -Competition for DNA binding sites. -Affinity for DNA - binding -Competition for protein-protein bindings. -Effects of concentraion of activators, specific TFs, and general TFs |
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What are insulators and what do they do?
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Insulators control the action of activators and in some cases repressors. Thy are found between enhancers and some promoters and block activation of the promoter. This prevents the transcription of the gene.
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What is synergy?
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Cooperative binding. The result is two activators working together. While one can only produce a basal layer of transcription, if there is another that the first can bind to and work together transcription is amplified.
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What is an enhancesome?
Describe the activation of the human interferon gene? |
- Enhancesome- Proteins bound cooperatively to sites tightly placed within an enhancer.
- Activated in cells upon a viral infection and undergoes the following steps. 1 - HMGA1 binds in the minor grove and helps assmble the enhanceosome. 2- Req. NF-kB, IRF, and Jun/ATF activators which bind cooperatively to an enhancor forming an enhancesome. 3-These activators then recruit CBP(CREB -binding protein) or p300 whcih is a HAT. |
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What is a transcriptosome?
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The basal complex, only thing needed for basal transcription (the complete initiation complex with the polymerase).
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4 ways that repressors work?
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1) Competition. Binding competes with an activator site.
2)Inhibition. Binding directly to the activator 3) Direct repression. Directly repressing the transcription machinery.(aka binding to an enhancer and then looping to bind to the mediator complex). 4) Indirect repression. Histone modifiers that alter nucleosomes in ways that inhibit transcription. It can bring in and bind to HDs, which will take off the acytelases and not allow transcripton to occur. |
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What is transcriptional silencing?
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Done by histone modifications and by methylation of the DNA itself by DNA methylase. These methyl groups prevent DNA sequences from being recognized by activator proteins. Note: some DNA seq. are only recognized when methylated.
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What are CpG islands and how do they work in the control of gene expression?
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CpG islands are extended sequences of Cs and Gs connected on the same strand of DNA by a phosphodiester bond (hence the p in the CpG). CpG islands allow for control because cytoseins are easily methylated and can be switched off (the gene) very easily.
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True of False - The basic machinery of development is essentially the same in vertebrates and the major phyla of invertebrates.
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True - the basic machinery of development is basically the same. Recognizably similiar related molecules define specialized cell types.
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What did Gurdon do?
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Using nuclear transplantation, he demonstated that a nuclei from a differentiated intestine cell into an egg, it would support normal growth.
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How do cells know where they are and supposed to go (liver cell, gut cells, etc.)?
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Signaling with other cells, methylation, and specific genes turned on or off.
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Name the 3 layers of the egg cell and what they become.
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- Ectoderm - precursor to the epidermis (skin) and the nervous system.
- Mesoderm, precursor to muscle, connective tissue, and various other components. - Endoderm, precurosor of the gut and its appendages. Lungs, stomach, liver, etc. |
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What is a fate map and what does it do?
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Tracer dyes are incerted into a cell of the embryo and then watched to see what its FATE will be (or where it will go). It could be a cell scheduled for death, to be a foot cell, lung cell etc.
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What is a way to make cells different?
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Expose them to different environments, the most important environmental cues acting on the cells in an embryo are signals from neighboring cells. NOTE: It is only a small subset of the component cells those closest to the source of the signal that take on the induced character
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Define Regionally determined and positional value.
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-Regionally determined: long before they were committed to differentiating as a specific cell type they became regionally determined. That is to say that they switch on and maintain expression of genes that can best be regarded as marked of position or region in the body.
-Positional value: The postion-specific character of a cell. It shows its effects in the way the cell behaves in subsequent steps of pattern formation. |
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What are inductive interactions? (Slide 105).
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Pretend that there are two blocks right next to eachother. Block A and Block B. Block B can induce a signal on block A. If a Block C was in between A and B, C is induced by signal from B acting on A. Etc. These inductive interactions can generate many types of cells starting from only a few.
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What are 3 characteristics of drosphilia development?
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-Nuclei are totipotent. Any nucleus can give rise to any and all cell types.
- Differentiation takes place w/out any change to genetic material. - Irrespective of where nuclei comes from. The egg is the only place where development can occur. |
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What cells later become the germ cells in a fly?
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Pole cells.
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Explain the main steps in drosophilia development.
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Look at slide 114
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Name the four independent systems of maternal effect genes.
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- Anterior
- Posterior -dorso-ventral -terminal |
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What are the gene switches in drosophilia development?
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- Anterior-posterior body plan
-Maternal RNA (codes for transcription factors) - Maternal protein gradients; transcription factors -Cell concentration of transcription factors. |
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What is the first step to triggering the cascade of gene expression in the determination of the fate of an individual?
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Maternal effect genes.
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What are zygotic genes and when are they produced?
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Genes of the zygote. Produced by the proteins that come froWhatm maternal effect genes.
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What is a rescue experiment? Explain how they learned they could do this.
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-Taking a biocoid mutant and adding normal cytoplasm allowing normal development.
-Mutations in a gene was discovered that controls the head and thoracic structures, the biocoid gene. This indicated taht there is cytoplasmic localization that determines the anterior end of the fly. |
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The Dorsal protein defines what three broad territories of expression?
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dpp, sog, and twist. Dpp and Sog interact with one another to set up a gradient of Dpp activity that guides a more detailed patterning process.
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What process makes the body plan of a develping animal more elaborated with finer and finer details?
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Sequential inductions - an example would be the dorsal proteins working together to form territories of expression. Dpp and sog work together to set up a gradient of dpp activity that guides a more detailed patterneing process.
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What are the three parasagment genes of the segment genes?
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-Pair rule genes
-gap genes - segment polarity genes. |
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Explain how genes are activated sequentially.
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Activated sequentially - each controlling a smaller more focused domain on the fly.
- Maternal effect genes produce different mRNA that then becomes protein after fertilization. These proteins start moving to the opposite end to where they were orignally clustered and form a protein gradient between the anterior and posterior side of the embryo. This triggers the activation of zygomatic or segmental genes, which are made up of parasegment genes - pair rule genes, gap genes, and segmental polarity genes. One of these genes (a gap gene) is hunchback and is only found in the anterior portion- where concentrations of bicoid are high. Hunchback has six binding sites to which bicoid can bind, three weak and three strong. Thus the concentrations of bicoid determine |
