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58 Cards in this Set
- Front
- Back
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why do proks & euks regulate gene expression? |
to respond to environmental conditions |
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in multicellular euks, gene expression (2) |
regulates development & is responsible for differences in cell types |
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? plays many roles in regulating gene expression in eukaryotes |
RNA molecule |
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how do bacteria respond to environmental changes? |
regulating transcription |
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1 mechanism for control of gene expression in bacteria is the |
operon model |
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cell can regulate production of enzymes by (2) |
feedback inhibition(product interferes with enzyme function gene regulation (product reduces amount of enzyme made) |
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5 difference between euk & prok genomes
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Euks: 1. genome = larger 2. more regulatory sequences 3. Most DNA doesn't code for RNA 4. multiple chromosomes 5. translation & transcription = physically separated by a membrane which allows for many points of regulation before translation |
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all organisms MUST regulate which genes are expressed at any given time - in multicellular organisms, regulation of gene expression is essential for... |
cell specialization |
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expression of different genes by cells with the same genome --> creates differences between cell types since almost all cells are genetically identical |
differential gene expression |
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chemical modifications to histones & DNA of chromatin influences both chromatin ___ & gene ___ |
structure expression |
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some euk genes have no homologs in proks, including genes that encode for (2) |
1. histones 2. proteins involved in processing mRNA |
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how is initiation and elongation of transcription blocked? |
Nucleosomes! DNA wrapped around histones |
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in histone modification.. what allows initiation? elongation? |
1. One remodeling protein leaves nucleosome to allow initiation * binding RNA pol to DNA 2. 2nd remodeling protein binds to nucleosomes to allow elongation |
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histone proteins have "tails" w/ __ charged amino acids - enzymes add __ __ to the tails to reduce positive charges, decreasing affinity of histones for negatively charged DNA allows __ ___ |
positive acetyl groups chromatin modification |
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Gene activation requires ___ __ __ to add acetyl groups Gene repression requires __ __ to remove acetyl groups |
histone acetyl transferases ( HAT ) histone deacetylases (HDAC ) |
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metylation of histones does what |
condenses chromatin --> heterochromatin |
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phosphorylation next to a methylated amino acid can |
loosen chromatin to allow transcription |
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adding methyl groups to certain bases in DNA (esp cytosine) - associated w/ reduced transcription - can cause long term inactivation of genes - can regulate expression of either the maternal or paternal alleles of certain genes |
DNA methylation |
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inheritance of traits transmitted by mechanisms not directly involving nucleotide sequence |
epigenetic inheritance |
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in regulation of transcription what is key? |
transcription factors |
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___ provides initial control of gene expressions by making a region of DNA more or less able to bind to transcription machinery --> (2) |
chromatin modifying enzymes transcription factors & RNA pol |
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associated w/ most eukaryotic genes are multiple ___ elements - segments of noncoding DNA: binding sites for transcription factors (regulates transcription |
control elements |
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far from RXN start site closer adjacent to start |
enhancers proximal elements promoter |
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____ sequence (near end of coding regions) ____ region (close or far from poly A signal |
poly a signal termination region |
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what 2 things control regulation of gene expression in different cell types? |
control elements transcription factors |
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initiating transcription, euk RNA polymerase requires assistance of ? general transcription factors are essential for ? |
activators transcription factors transcribing all protein coding genes |
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protein that binds to an enhancer & stimulates transcription of a gene 1 domain : 2 domain : |
activator binds DNA binds proteins that initiate transcription |
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Bound activators facilitate protein protein interactions that result in (2) |
initiation complex forming gene being transcribed |
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transcription factors can act as ___ , inhibiting expression of a particular gene by a variety of methods |
repressor |
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how do activators & repressors act indirectly to promote or silence transcription |
influencing chromatin structure |
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a particular combination of control elements can activate transcription only when... |
appropriate activator proteins are present |
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_____ eukaryotic genes aren't organized in operons - these gene = scattered over different chromosomes but each has same combination of control elements - activators can recognize specific control elements & promote simultaneous transcription of genes |
co -expressed genes |
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more genes or mRNA? |
mRNA |
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post transcriptional regulation |
alternative rna splicing |
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key to determining protein synthesis? |
life span of mRNA molecules in cytoplasm |
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where are nucleotide sequences that influence lifespan of mRNA in euks reside? |
UTR 3' of mRNA ( and 5' ) |
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1. length of time each protein FXN is regulated by ? 2. cells mark proteins for degradation by attaching ? 3. mark is recognized by __ & degraded by proteins |
selective degradation ubiquitin proteasomes |
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can noncoding RNAs play many rules in controlling gene expressioN? |
yes |
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non protein coding DNA has genes for RNA such as... |
rRNA & tRNA |
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noncoding RNAs regulate gene expression @ 2 points : |
mRNA translation & chromatin configuration |
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- small single stranded RNA molecules that can bind to mRNA - degrades mRNA or blocks translation - completely complementary --> - match less complete --> |
miRNAs degradation block translation |
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similar to miRNA exogenous ( from virus or human made) |
siRNAs |
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blocking of gene expression by siRNAs is called |
RNA interferance |
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can ncRNA remodel chromatin structure? what reforms heterochromatin at centromeres after chromosome replication? |
yes siRNA |
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initiation of translation can be controlled via regulation of? |
initiation factors |
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process by which cells become specialized in structure & FXN - important for use of embryonic stem cells to treat diseases |
cell differentiation |
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maternal substances in egg that influences early development |
cytoplasmic determinants |
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as zygote divides through mitosis, cells contain different cytoplasmic determinants which leads to different |
gene expression |
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signal molecules from embryonic cells cause transcriptional changes in nearby cells |
induction |
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irreversibly commits a cell to its final fate precedes differentiation cell differentiation is marked by production of tissue specific |
determination determination proteins |
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development of a spatial organization of tissues & organs - in animals, it begins w/ establishment of the major axes |
pattern formation |
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molecular cues that control pattern of information - tells a cell its location relative to the body axes & to neighboring cells |
positional information |
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encodes cytoplasmic determinants (which initially established axes of body of Drosophilia) |
maternal effect genes |
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a maternal effect gene that controls the front half of body |
bicoid |
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why was bicoid research ground breaking? |
- ID'd a specific protein required for early steps in pattern formation - increased understanding of mother's role in embryo development |
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key concept of bicoid experiment? |
gradient of molecules can determine polarity & position in embryo |
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mutations in genes that cause cancer (2 reasons) |
1. spontaneous mutation 2. environmental inflences |
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transformation can produce a ___ |
tumor |
