eukaryote gene regulation Flashcards
(25 cards)
what must multicellular organisms activate or deactivate their genes according to?
-external stimuli
-internal stimuli
-regulate genes according to the type of cell
where can the expression of eukaryotic genes be regulated?
-chromatin modification (DNA and protein)
-transcription
-RNA maturation
-translation
-degradation of proteins
what am I:
-complex of DNA and protein found in eukaryotic cells
-primary function is toc pack DNA into more compact structures
-primary protein component is histones, which bind to the DNA wrapped around them
chromatin
what does the acetylation of histones lead to?
-it leads to the loosening of the structure of chromatin
-loose structure of chromatin permits access of the RNA polymerase to the DNA and the initiation of transcription
what is the methylation of histones?
-it is the modification of certain amino acids in a histone protein by the addition of 1, 2, or 3 methyl groups
-associated with transcriptional repression
-methylation of some lysine and arginine residues of histones results in transcriptional activation
what is ATP-dependent chromatin remodeling?
-functions as molecular motors that uses energy from ATP hydrolysis to alter the relationships between histones and DNA
-makes DNA more accessible to regulatory proteins
what is epigenetic inheritance?
-alteration that must persist int he absence of initiating stimulus and must be inherited through cell division
-DNA methylation and histone modification change the way genes are expressed but not the DNA sequence
what is DNA methylation?
addition of methyl groups to certains bases in DNA
-associated with reduced transcription in certain species
what are the 2 types of transcription factors?
-general transcription factors
-specific transcription factors
what are general transcription factors and what are their roles?
-proteins that bind to DNA promoter
-necessary to recruit RNA polymerase II to a promoter and assemble an initiation complex
-required for transcription to occur, but do not increase the rate above basal rate
what are specific transcription factors and what are their roles?
-high levels of transcription of particular genes depend on the control elements interacting with specific transcription factors called an activator
-activators act in specific tissue or in a time-dependent manner to stimulate high levels of transcription than basal level
what are the 2 protein domain of an activator? (specific transcription factor)
-DNA-binding domain: recognized a specific sequence of DNA of the control element
activation domain: interacts with transcription apparatus
what is each enhancer composed of?
-approximately 10 control elements (each one can only link 1 or 2 specific coactivators, mediator proteins, and transcription factors)
true or false: virtually all genes that are transcribed by RNA polymerase II need the same suite of general factors to assemble an initiation complex
true
which is higher; the lifespan of eukaryotic m-RNA or the lifespan of prokaryotic m-RNA?
eukaryotic m-RNA (half-life of 10 hours)
why does eukaryotic m-RNA have a longer lifespan?
so it can be translated several times if necessary
where is the nucleotide sequence that influences the lifespan of eukaryotic m-RNA located?
in the untranslated region (UTR) at the 3’ end of the molecule
what process leads to the degradation of eukaryotic m-RNA?
enzyme recognized a sequence in UTR and cuts the poly-A tail leading to the degradation of m-RNA by exonuclease
what am I:
-small single stranded RNA that are coded in DNA, but do not produce proteins
-have specific bases that bind to m-RNA
-forms a complex with the protein that cleaves the m-RNA or blocks its translation by the ribosome
micro RNAs (mi-RNA)
what am I:
-arises form a long piece of double-stranded RNA
-processed by dicer to yield said thing
-associated with proteins that will cleave the m-RNA when they will find a complementary base pair
-most likely evolved to protect agains tRNA virus by silencing them
small interference RNA (si-RNA)
how does the blocking of translation of m-RNA occur?
initiation of translation of selected m-RNA can be blocked by regulatory proteins which bind to m-RNA sequences (usually in 5’ or 3’ UTR) and prevent the ribosome from binding
-translation of all m-RNAs in a cell can be regulated simultaneously
why are proteins degraded/destroyed?
if they are not useful anymore or have been damaged
how is the labeling of a protein for destruction carried out
by attaching ubiquitin protein to targeted protein
who am I:
organelle that degrades proteins marked with ubiquitin
proteasomes: contain protease enzyme that cuts protein in small polypeptide fragments
isolates protease enzyme from the rest of cell and prevents arbitrary destruction of other proteins
