Term
| Describe Spatial and Temporal Expression |
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Definition
Spatial: not every gene product is needed in every tissue
ex. Tubulin is Arabidopsis
Temporal: not every gene product is needed at all times
-seen in development
ex. fetal hemoglobin |
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Term
Describe the following mechanisms of gene regulation
1. Controlling trxn of DNA
2. mRNA splicing
3. mRNA stability |
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Definition
1. complex, using signal transduction
-middle man relays signal
-one output can affect multiple things
2. two introns spliced together can remove exon or alternate intron can cause alternate exon
-part of plan to regulate
ex. Drosophila sex chromosome
3. one mRNA can be translated many times
-rapid degradation can occur by adding AUUUA repeats in 3' UTR |
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Term
Describe the following example of Eukaryotic Gene Regulation:
Heat Shock Proteins |
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Definition
-HSP stabilize cellular functions at high temps
-act as chaperone proteins to keep protein folding
-higher temperature -> more HSPs
Drosophila HSP70
-when temp goes above 33, HSPs ramp up production
-forms HSFactor trimer that activates polymerase |
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Term
Describe the following example of Eukaryotic Gene Regulation:
Light RBC gene in plants |
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Definition
-Ribulose 1,5-Bisphophate Carboxylase used in photosynthesis
-TF is rbcS and only activated when light is present
-mRNA expressed in high amounts with light |
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Term
Describe the following example of Eukaryotic Gene Regulation:
Hormones |
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Definition
-regulated through receptors
Steroid: similar to lipids so they pass through membrane
-bind to receptor and then enter nucleus
-receptor is the TF
Peptide: cannot pass through membranes
-bind to receptor on membrane
-activates cytoplasmic protein and induces a signal molecule
-signal molecules activates TF |
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Term
| Describe Transcription Factors |
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Definition
-allow RNA poly to bind controlling initiation
-TF bind to enhancers and control elongation
2 Domains
1. DNA binding-regions of protein that bind to DNA
a. zinc finger motifs
b. helix turn- fits into major and minor groove
c. leucine zipper- every 7th is Leu, hydrophobic, so they come together and form clamp on DNA
2. Activation Domain- Poly has basic stretches so TFs contain acidic stretches to bind to poly |
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Term
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Definition
TF bind to them to regulate gene expression
1. act over long distances- DNA can loop up making them spatially closer than the bp sequence
2. independent of orientation- can be inverted
3. found upstream and downstream- intons |
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Term
| Describe RNA Interference |
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Definition
1. double stranded RNA from virus
2. cuts RNA into fragments
3. ssRNA carried around by RISC (RNA induced silencing complex) until it finds matching RNA
4. siRNA- matches perfectly and is cleaved
miRNA- not perfect so translation is inhibited
*miR genes function to inhibit other mRNA |
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Term
| Describe Chromatin Architecture |
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Definition
-spatial organization is important
-if packaged too tightly, poly can't bind
Euchromatin- loose (most genes)
Hetero-dense
Ex. heat activates HSTFs, so area puffs out
-allows for poly to bind and transcipt HSP
Opening of DNA can occur by:
1. Moving nucleosomes- SWI/SWF
2. Modifying nucleosomes- acetlyation makes ARG and LYS basic so they can't bind and DNA is free |
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Term
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Definition
methylation = repression
-CpGs are methylated and gene is silenced |
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Term
| Describe Gene Amplification |
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Definition
1. more numbers of genes- more mRNA (5s genes)
2. highly replicating plasmids |
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Term
Describe X Chromosome Alteration
1. Inactivation
2. Hyperactivation
3. Hypoactivation |
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Definition
1. Female Chromosome
-X inactive specific transcript (XIST)
-if turned on, will make protein that coats X and stops all transcription
-XIST must be turned off for chromosome to work
-relies on methylation
2. activate to higher level
3. decrease activation of both |
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