What is the genome structure of a eukaryotic cell?
nuclear membrane, linear chromosomes, condensed chromatin by histones, multiple replication origins, singe gene transcription
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Which organism can contain operon like structures?
C. elegans
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Do eukaryotes have linear or circular chromosomes?
linear
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Do eukaryotic cells have multiple replication origins?
yes
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Do eukaryotes have multiple gene transcription?
no
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What are similarities between eukaryotic and prokaryotic expression regulation?
RNA polymerases allow transcription, mRNA transcript translated into protein by ribosomes, genetic code is nearly universal
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What are the three types of RNA polymerase?
polymerase I, polymerase II, polymerase III
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what does polymerase I transcribe?
rRNAs
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What does polymerase II transcribe?
pre mRNAs, snoRNAs, some miRNAs and snRNAs
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What soes polymerase III transcribe?
tRNAs, small RNAs, miRNAs, some snRNAs
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How many additional polymerases have been found in plants?
two
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What must happen to eukaryotic DNA before transcription?
DNA must unwind from histone proteins
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Where does protein synthesis take place?
transcription in nucleus, mRNAs then transported into cytoplasm - on ribosomes, for translation
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How many genes does one promoter control?
one gene
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What do basal transcription factors do?
they respond from injunctions from activators. They position RNA polymerase at the start of transcription and initiate the transcription process
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What is the role of repressors?
they bind to selected sets of genes at sites known as silencers, and slow transcription
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What do activators do?
these proteins bind to genes at sites called enhances and speed up rate of transcription
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What do coactivators do?
these adapter molecules integrate signals from activators and perhaps repressors
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Why is it that not all genes are active at any given time?
Because it requires energy for a gene to be transcribed and translated, turning genes that aren't required off conserves energy
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What does increasing the amount of activator binding sites do?
it can increase the efficiency of recruiting the transcription machinery, such as activators and basal transcription factors
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What is the base sequence of the beginning of the core promoter?
TATA
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Can different sequences be mixed and matched in different combinations?
yes, a different transcriptional activator protein binds to each consensus sequence, so each promoter responds to a unique combination of activator proteins
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What is an insulator?
a DNA sequence that blocks or insulates the effect of enhancers, they often lie between the enhancer and the promoter
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What is transcriptional stalling?
when the progress of the RNA polymerase is stalled after the initiation of transcription, then when the right cue is present transcription elongation blocks are released so transcription can proceed
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What does transcriptional stalling allow?
faster transcription of genes when needed
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What specific proteins is transcriptional stalling used for?
heat-shock proteins and sometimes other genes
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How can chromatin structure be altered?
chromatin remodelling complexes, histone modifications, DNA methylation
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What type of histone modifications
methylation and acetylation
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Can changes in chromatin structure affect gene expression?
yes
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Why does chromatin structure vary over time?
to allow transcription of RNAs
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How is chromatin remodelled?
changes in chromatin structure by repositioning nucleosomes, thus exposing binding sites on DNA (18.2 on textbook)
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What does chromatin remodellin allow?
transcription factors to bind to DNA and initiate transcription
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How is chromatin remodelling mediated?
by chromatin remodelling complexes binding to specific DNA sites, the complexes include transcription factors and regulatory proteins
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Other cards in this set
Card 2
Front
What is the genome structure of a eukaryotic cell?
Back
nuclear membrane, linear chromosomes, condensed chromatin by histones, multiple replication origins, singe gene transcription
Card 3
Front
Which organism can contain operon like structures?
Back
Card 4
Front
Do eukaryotes have linear or circular chromosomes?
Back
Card 5
Front
Do eukaryotic cells have multiple replication origins?
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