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Genetics 380 > Gene Regulation in Eukaryotes > Flashcards

Gene Regulation in Eukaryotes Flashcards

1
Q

key to being complex organism

A

gene regulation not more genes

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2
Q

constitutive (housekeeping) genes

A

always on at all time in all cells (ex: actin and other genes that make components of the cytoskeleton, genes that make enzymes that carry out glycolysis)

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3
Q

inducible/repressible genes

A

level of activity changes as your needs change (ex: metallothionein and genes whose proteins clear metals can be induced by the presence of metal in the body)

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4
Q

tissue dependent gene regulation

A

responsible for differentiation of different tissue types; subset of genes that get turned on determine what proteins cell has which determines properties that cell has; tissue specific epigenetic difference in genes

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5
Q

cell division

A

cells become more specialized w every cell division

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6
Q

globin genes

A

time dependent gene regulation; gamma-Hb has higher affinity of O2 than beta-Hb which allows fetus’ Hb to take O2 out of the mother’s blood

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7
Q

biochemical individuality

A

differences in gene activity levels; gene regulation is variable btwn individuals so level of activity in most proteins variable btwn inds

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8
Q

epigenetic factors

A

regulation of gene express that does not involve changing the sequence of bases in the gene; factors that influence chromatin configuration

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9
Q

DNA packaging

A

chromatin config. changes to make promoter region more/less accessible to transcription factors

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10
Q

facultative heterochromatin

A

some heterochr regions packed as heterochr in one cell but euchr in another cell; some exist mostly as heterochr but can decondense temporarily and express genes in region in response to certain molecular signals

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11
Q

transcription initiation

A

interactions btwn regulatory sequences and transcriptional activators/inhibitors

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12
Q

RNA processing

A

alt cleavage and splicing of pre-RNAs

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13
Q

RNA stability

A

poly-A-tail and interferring RNAs regulate RNA longevity

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14
Q

translation initiation

A

5’ and 3’ UTRs and interfering RNAs regulate rate of translation

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15
Q

cis acting transcription regulation

A

lie on the same chr as the gene (ex: promoters, enhancers, insulators and other seqs that lie in the regulatory regions)

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16
Q

trans acting transcription regulation

A

produced elsewhere and bind the regulatory sequences (ex: activators, repressors that bind to promoter region or insulator binding proteins)

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17
Q

transcriptional activators/repressors

A

bind to reg promoter or enhance and can increase rate of transcription or keep the gene silenced

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18
Q

transcription factor protein complex and RNA polymerase

A

bind to core promoter and provide ability to transcribe but at minimal rate

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19
Q

step one in signal transduction

A

hormone binds to extracellular domain of receptor protein (surface of cell)

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20
Q

step two in signal transduction

A

receptor protein has intracellular domain that initiates biochemical cascade often involving phosphorylation of proteins inside cell

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21
Q

step three in signal transduction

A

biochemical cascade alters transcription factor and allow it to enter nucleus and activate/inhibit its target genes

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22
Q

response element

A

promoter seq. that is found in promoter regions of several genes whose proteins must work together; enable eukaryotes to regulate multiple genes simultaneously and coordinately regulated; one event (heat, stress) can activate/inhibit # of genes whose proteins help cell cope w the event

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23
Q

insulators

A

prevent gene activation by transcription factors

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24
Q

chromatin configuration

A

regulates gene activity: heterochromatin, euchromatin, supercondensation of heterochromatin; chromatin must be rearranged to allow transcription factor proteins and RNA polymerase to access the gene’s promoters (even in euchr)

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25
regulatory sequences
must be accessible to transcription factors for transcription to occur
26
DNAse I
enzyme that cuts DNA next to each pyrimidine nucleotide (C and T) cuts DNA down to approx. 1-8 bp fragments; more relaxed chromatin is more sensitive to DNAse; more transcriptionally active regions are more sensitive to DNAse I
27
chromosome puffs
form in regions in which several genes are active for some species (ex: drosophila)
28
common chemical modifications
methylation of histones (often the lysines) acetylation of histone proteins (often at positively charged lysines) and methylation of DNA (often the Cs in CG island in the promoter region)
29
methylation of histones
regulates transcription; can enable activation or repression of gene activity depending on specific amino acid that get methylated
30
H3K4me3 methylation
3 methyl groups added to lysine number 4 in histone 3 aka H3K4me3 (K = lysine) enhance transcription; some proteins that bind to H3K4me3 decondense the local chromatin
31
acetylation of histone proteins
makes DNA accessible to transcription factors
32
chromatin remodeling complexes
control gene activity; complexes of transcription factors and other proteins that move nucleosomes around exposing promoter sites so transcription factors can bind them; some slide nucleosome down DNA exposing promoter region; some change conformation of DNA and/or nucleosome exposing promoter
33
DNA methylation
inhibits transcription of genes in that region; methylation of cytosines in promoter regions of genes = prevents transcription factors from binding transcription doesn't occur; 2-7% of all cytosines methylated in eukaryotes (not in drosophila or yeast)
34
increased trinucleotide repeat
increases methylation and leads to fragile X syndrome; FMR1 gene has trinucleotide repeat (CGG) in promoter which can expand during meiosis; too many leads to increased methylation and deacetylation of histone protein inhibition of transcription of FMR1 and fragile X mental retardation syndrome
35
X-inactivation
silences most of the genes on one X chromosome in humans; deleterious to development to have 2 active copies of every genes on X chromosome
36
XIST RNA
X that gets inactivated produces this specific RNA called X-inactivation specific transcript XIST; coats chromosome super condenses and fosters methylation of promoter region
37
TSIX RNA
produces by other X to protect itself; complementary to XIST RNA the two bind preventing XIST RNA from inactivating second X
38
Barr body
super condensed inactivated X chromosome
39
imprinted gene
regulated by different methylation of the promoter regions; methylation of Cs followed by Gs in CG islands represses transcription
40
gametogenesis
during spermatogenesis and oogenesis DNA is completely unmethylated then remethylated in appropriate pattern that comes from parent of your sex; problems could result in 2 or 0 working copies of imprinted genes
41
methylated DNA binding proteins
have domain that binds methylated DNA and domain that has histone deacetylase activity; tighten chromatin in regions where promoter region Cs are methylated
42
MECP2
X linked gene mutations have sex influenced side effects; Rett syndrome in females
43
Rett syndrome
cause by MECP2 mutation; normal development for approx. 6 months then regression of cognitive capabilities and head ceases to grow resulting in microcephaly; extremely variable expressed syndrome featuring cognitive impairment and other CNS features in males
44
identical twins
develop different traits and different patterns of DNA methylation and histone acetylation
45
early life experience & epigenetic factors
level of methylation of DNA influence by amount of licking rat receives during infancy; effects seen on glucocorticoid receptor gene/protein and offsprings' responses to stress and persist into adulthood
46
epigenetic factors & diet
bees and royal jelly: RJ silences DNA methyltransferase 3 gene (Dnmt3) which changes methylation of/expression of # of genes causing female to develop as queen and able to reproduce
47
heritable epigenetic factors
pregnant woman w metabolic abnormality (diabetes, high blood lipids) can change methylation pattern of her genes and some of child's genes; set as if child's body is expecting to experience same nutrition after birth as before: after born does not metabolize nutrients optimally
48
stressed female rat
changes in all generations; changes in methylation of glucocorticoid gene in offsprings' brains
49
gender & epigenetic factors
obese mom rat consistently obese daughters; obese father 15% obese daughters
50
paramutation
heritable changes in gene expression due to epigenetic effects (ex: corn spotting)
51
Kit(t) allele
produces microRNA that degrades the Kit mRNA; lethal
52
Kit gene
contributes to pigmentation; heterozygotes have white tails and feet
53
specialized DNA methyltransferases
maintain epigenetic changes through DNA replication; some specifically recognize and methylate hemimethylated DNA which methylates newly synthesized DNA strand
54
complex organisms & more complex gene structure
ability to produce multiple proteins from single gene; different isoforms
55
different isoforms
same active domains but different regulatory domains which allows different tissues to turn the protein on and off at different times; also have have different activities and perform different functions
56
alternative splicing
allows one gene to make several different isoforms of its proteins; can let one gene make different proteins in different cells
57
sex determination in drosophila
regulated by alternative splicing of transformer (Tra) gene mRNA by the sex-lethal (Sxl) protein
58
poly-A binding proteins
bind to poly-A tail to stabilize mRNA but one tail shrinks to approx 10-30 As poly A binding proteins can't bind to poly A tail any more and mRNA degrades; mRNA must be stabilize if they're gonna remain in cytoplasm long enough to be translated
59
interfering RNAs (iRNAs)
microRNAs (miRNAs) and small interfering RNAs (siRNAs); formed when longer double stranded RNA precursor is cleaved in cytoplasm by enzyme Dicer both join w proteins to make up RISC (RNA induced silencing complex); have base sequence that is complementary to some portion of either mRNA's sequence or gene's sequence so iRNA can bind to either mRNA or gene itself
60
siRNAs
exogenous double stranded RNAs that are taken up by cells or enter via vectors like viruses
61
miRNAs
single stranded and endogenous - transcribed from sequences in cell's genome - some are found w/i introns of genes; some of what was once nonfunctional "junk" DNA has turned out to include miRNA encoding sequences
62
inhibition of translation
if iRNA can bind to some portion of 5' end of mRNA this will prevent ribosome from reading mRNA
63
cleavage of mRNA
RISC complex includes endonucleases that cleave double stranded RNAs; if iRNA binds portion of mRNA endonucleases will cleave mRNA
64
RISC complex
includes endonucleases that can cleave mRNA
65
Fire and Mello
able to completely abolish protein production w concentration of iRNA that delivered approx. 2 molecules of iRNA per cell
66
iRNAs & methylation
cause gene to be methylated inhibiting transcription; other iRNAs attach to complementary sequences in DNA and attract methylating enzymes which methylate DNA or histones and inhibit transcription; some inhibit protein production by unknown mechanism
67
lincRNA-p21
represses action of transcription factor p53 which regulates number of genes whose proteins regulate cycle and apoptosis
68
p53
dysfunction is involved in human cancer; regulates number of genes whose proteins regulate cycle and apoptosis
69
ubiquitin
tags proteins for degradation; brings proteins to proteasome to be degraded - proteins that attach ubiquitin to specific target proteins can be increased or decreased altering the lifespan of the protein

Genetics 380 (11 decks)

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